Don’t skimp on the power supply: a 20 kW solar installation reviewed

There are a lot of reasons I decided to have a big honkin’ solar array installed on my roof. I’ll get to the tangible ones shortly—backed by cold, hard data. The main reason that comes to mind, though, is less concrete. It’s a feeling, or an instinct; a desire to realize the expectations of my 20th-century childhood as a 21st-century adult. This is something I’ve wanted even before I plopped down my first solar power plant as an 11-year old SimCity 2000 mayor. My infatuation with solar arrays has grown.

Now, I understand that the emotional investment I have in this venture isn’t something everyone is going to share. Still, it’s an undeniable factor in my decision-making process. My parents were promised an inevitable fusionpoweredrobotfilledsmarthome by science fiction when they were kids. Hanna-Barbera’s vision of the future may not have come to pass, but I want my daughters to grow up in that futuristic fantasy, so it’s up to me to deliver on that dream.

Beyond being simply a cool toy that I’ve wanted since I was a kid, or a sound investment I can make now that I’m all grown up, I consider this project to be a personal moral imperative. That may be a ironic phrase to invoke for what should be a by-the-numbers adventure, but I was happy to find that both my wallet and my conscience would be soothed by this endeavor. The math works out, but I’ll add this much: I’ve already left my mark on the planet, and now I want to erase it. I think this is a good start.

And so, it begins

As any adventure should, I began with research. Question number one was, “does solar power even make sense in Michigan?” Following closely behind, there was a second question of “exactly how large of an installation would I need?” There are tons of calculators online for finding those answers, and I used more than a few to get multiple opinions. Ultimately all the numbers really clicked for me once I saw the map below. It breaks down solar irradiance into kWh-per-kW-of-panels-installed, per year.


Image source: solarpowerrocks.com

That image is backed up by the feds and other resources online. You can see that Michigan’s 1400 kWh/kW-yr ranking isn’t amazing, but it isn’t tragic either. Since my goal was to offset 100% of my electrical consumption with solar energy, the math here is pretty easy. All I had to do was add up my annual kWh usage based on my electrical bill, then solve for X. In 2018, our household included an entire extra family for eight months. That lead to an over-the-top electrical consumption of 25,650 kWh for the year. In 2017, our usage was more normal, clocking in at 20,263 kWh. Overkill is underrated, so I used the total from 2018 for my calculations. Also, solar panels lose about 0.5% of their production each year—another reason to aim high.

A solar panel system’s capacity is expressed as its peak potential output, or kWp. I divided my consumption of 25,650 kWh by the 1400 kWh/kW-yr from the map and came up with a requirement of an 18.32 kWp system. The calculations aren’t quite that easy, though. There are other factors to consider, like the laws of physics. Any system is going to have efficiency losses. Roughly speaking, you’re talking about needing an extra 20-25% more capacity to counter those losses. That brings my requirements up to 22.9 kWp for my 2018 numbers and 18.09 kWp if I look back to my 2017 usage. With that, I had my rough estimate.

Of course, there’s still more to it than that. There’s potential shade to consider, as well as the directions the panels are facing, and the pitch of your roof. Those variables are a bit too specific to be within the scope of this piece, though. Just know that they will come into play when you start fooling with full-fledged solar calculators online. In my case, you’ll soon see that shade was not a problem for me. I do however have an east-west facing roof instead of a the idyllic southern facing one. As it turns out, that’s not nearly as significant a factor as it used to be with today’s modern panels and their prices.

Speaking of problems—Fish, you idiot. The. Sun. Goes. Down. That’s where “net metering” comes in, though. Net metering means you can bank credit with your power company when you produce more power than what you’re using. Think of it as using the electrical grid as a battery, at least financially. Alternatively, think of it as old-school rollover minutes on your cellphone. You’ll have to do your homework to see if it’s available where you live, but it made everything a lot easier (and cheaper) for me.

Net metering is critical, because unless you plan on storing all the excess power yourself (more on that later), any solar panel array you invest in is only going to lower your bill while it’s actively generating power. You’ll still be drawing from the grid when it’s dark, cloudy, or when the panels are covered in snow. Without net metering, there would be no point to installing a system capable of producing more power than you use during the day. The bottom line is that with that ability, you can install whatever size system you want without having to worry about what to do with the power you’re not using in real time.


Number of minutes between sunrise and sunset for my latitude and longitude. Source: USNO

In my case, the type of net metering at my disposal means that any excess power I produce in a month carries over to the next month as a credit on my bill. I don’t get paid cash for producing more power than I need, but the credit stays on my account for 12 months. At that point, any surplus I may still have drops off. It’s early days yet for my system, but my hope for this year is that I’ll bank up enough credit over the spring, summer, and fall to be able to get through next winter (when the panels are covered with snow) by pulling from my credits. We’ll talk about how that’s working out so far in a bit, and my intention is to revisit that specific topic six months from now, and again six months after that.

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Colton Westrate

I post Shortbread, I host BBQs, I tell stories, and I strive to keep folks happy.

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robung
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robung

In the billing cycle data, what is the difference between “Self Consumption” and “Consumption”? How is “Import” and “Export” calculated (I can’t seem to make the math work out)? Do I assume that “Export” – “Import” represents the kWh being netmetered?

jdrandom7@gmail.com
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jdrandom7@gmail.com

One thing to consider is that every kW that you convert into electricity is a kW you can subtract from your air conditioner’s heat load. Even if the panels were not generating anything, they would be blocking a ton of radiant energy from hitting your house. I expect you are finding that your AC is using significantly lss power than previous years.

ratborg
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ratborg

Very informative and well-written article. Thanks for providing so much detailed (and personal) information. Whether or not solar is for everyone it’s nice to read a write-up like this.

drfish
Guest
drfish

I got my net metering spreadsheet and April’s power bill today.

$6.84 for the honor of being grid-connected.

$177 in credit toward my next bill.

$239 in credit total since 3/1.

I’m a happy camper.

Redocbew
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Redocbew

Fish, you idiot! What were you waiting for?

Kevin Sweeney
Member

Cool, thanks for the update and the article!

TurtlePerson2
Guest
TurtlePerson2

Tesla is slashing prices in an effort to drive up volume.

[url<]https://www.cnn.com/2019/05/01/investing/tesla-solar-panel-costs/index.html[/url<] This is coming just after analysts were saying that the price for solar cells might rise again. It could have the effect of making 2019 the best year to go solar for a long time.

gerryg
Guest
gerryg

Bring yourself a shrubbery!

“The same lack of shade that makes my house good for solar also makes it a bear to keep cool.”

Nice thick/wide shrubs ( < 8ft tall) along the sides of the house that get the most sun can make a huge difference on cooling in the summer by preventing the walls and foundation and ground close by from absorbing tons of heat, and especially then radiating it into the house at night. If they lose their leaves in winter, even better because then you get the sun back for warmth when you need it. Worth looking into.

Ni!

Usacomp2k3
Guest
Usacomp2k3

Any recommendations on specific plants?
From a security standpoint shrubs up against the house aren’t a good idea.

anotherengineer
Guest
anotherengineer

In your payback calcs,

did you assume
-no broken or degraded solar panels over that time?
-no degraded batteries over payback lifetime?
-no defective or failed electrical components of the payback lifetime?
-labour to replace anything over payback lifetime that fails out of warranty?
-interest lost on investing 65k?
-interest paid on the loan?

just curious

If one could get 5% on 65k that would be about $271/mo.

albundy
Guest
albundy

i’m planning on eventually setting up a solar array, and hopefully not spend that much cash. it will be a DIY project.
i want my panels to be on the ground level for easy cleaning and maintenance , and on dual axis actuators that automatically track and pivot towards the sun to maximize charging my batteries during the day. i do like the idea of also having net metering, as being hooked up to the grid and selling any power excess of what the batteries can hold.

something like this, but slightly bigger.
[url<]https://www.youtube.com/watch?v=hr07xKWM6tw[/url<]

drfish
Guest
drfish

While that is decidedly cool and looks like a fun project, what I’ve read is that, generally speaking, trying to min/max a smaller number of panels is not as cost effective as just buying more panels instead. Also, caring for moving parts on a structure being battered by wind and weather sounds like too much maintenance for my taste.

enigma
Guest
enigma

Holy shit! 350$ a month electricity bill! What are you doing in the US?

Here in Germany my parents household is like 120 € / month and thats a lot. My 2 person hosehold uses like 20 € a month.

drfish
Guest
drfish

I know $275/mo isn’t much better. But that [i<]was[/i<] with 12 power hungry people in our house, heh. It goes up the more you use too, our peak bill last year was $555 for July. That works out to [b<]$0.18/kWh[/b<] vs. the $0.15/kWh for this January's $259 bill.

enigma
Guest
enigma

That’s cheap. Germany is flat for like 0,28 € kWh + meter rental fee (btw the gallon fuel is like 5,86 € here).

12 people is a lot! Maybe you should restrict mobile device usage in order to save power 😉

drfish
Guest
drfish

If we took the tablets away from the kiddos it would be chaos beyond imagine. o_0

Leader952
Guest
Leader952

I doubt that tablets are your main source of power usage.

Heating (electric/heatpump) and Cooling are the main ones and probably 60-75% of the bill.
Followed by electric water heaters, dryers and stoves/ranges.

Leader952
Guest
Leader952

[quote<]It goes up the more you use too, our peak bill last year was $555 for July. That works out to $0.18/kWh vs. the $0.15/kWh for this January's $259 bill.[/quote<] That sucks (goes up the more you use). Here in Texas you can pick your own plan. Some are like what you have but here you can get ones that don't go up the more you use. Infuse Energy [url<]https://www.infuseenergy.com[/url<] Essential Infusion 36 Fixed Rate 36 Months 16% Renewable Facts label: [url<]https://88fd201f32c53c2bd0fb-11ba98ed637230a2314ec7c228a44bda.ssl.cf5.rackcdn.com/201904/EFL-20190422-143214-Essential%20Infusion%2036%20(English).pdf[/url<] Oncor Delivery 9.5¢ - 500 KWh 9.0¢ - 1000 KWh 8.7¢ - 2000 KWH Total bill cost is: 5.290¢ per KWh Energy charge + 3.315¢ per KWh Oncore delivery charge +$2 --- For those who live in Texas you can go 100% Renewable via NEW POWER TEXAS at 9.2¢ per KWh: [url<]https://newpowertx.com/EmailHTML/efl.aspx?RateID=413&BrandID=5&PromoCodeID=0[/url<]

Arclight
Guest
Arclight

Haven’t kept up with hardware in years and all the new video card and CPU name designations are unknown to me, but this article has me more interested.

BIF
Guest
BIF

I live in Central Florida and one side of my roof faces southeast, perfect to grab the morning rays and avoid losing power generating opportunity when the summer afternoon clouds and rains come. After some loose calculations I made some 6-7 years ago, I figured that I could outfit the roof and generate at least 75% of my electrical usage. The cost back then was going to be at least $45,000, but now I think that is just about halved today. One of my neighbors just put panels on his house, and he can monitor everything from his smartphone. He… Read more »

Wirko
Guest
Wirko

The Sunfish dashboard doesn’t show the correct date when the power plant was installed – it shows the current date instead. It’s the same with the other plants at solaredge.com. What’s up?

drfish
Guest
drfish

Weird. It looks like all of them show the current date. On my logged-in panel I see the date the system went live, 3/1/19.

Blink
Guest
Blink

Fun read. Thanks for taking the time to post.

flashbacck
Guest
flashbacck

Well, now you need a wind turbine to compensate for the lower solar power in the winter!

drfish
Guest
drfish

Believe me, I’ve thought about it. We’ll see how far net metering gets me first, though.

oldog
Guest
oldog

Colton, your case scenario is a good example of why many smart people are now saying that the problem with solar is not that it produces too little electricity at night or in bad weather but exactly the opposite. The problem is that solar panels produce too much electricity for the grid.

[url<]https://www.technologyreview.com/s/611188/california-is-throttling-back-record-levels-of-solarand-thats-bad-news-for-climate-goals/[/url<] [url<]https://www.smh.com.au/business/the-economy/too-much-of-a-good-thing-solar-power-surge-is-flooding-the-grid-20180606-p4zjs7.html[/url<]

drfish
Guest
drfish

Totally agree. Fortunately, I think it’ll be awhile before Michigan has insurmountable problems of that nature. If it becomes a problem, I can always add a second battery (the LG is designed to run as a pair) and switch gears to using my own stored power regularly instead of just as a backup.

oldog
Guest
oldog

Agreed.

shank15217
Guest
shank15217

You should invest in an electric car, A Tesla Model 3 would be my suggestion. You generate a ton of kw per day and the car battery is 75kW so you can basically have free transportation. You are light on the battery, it’s sufficient for home usage though.

drfish
Guest
drfish

It’s on my list.

dragontamer5788
Guest
dragontamer5788

Honda Clarity is on my electric car list. 47-miles all electric, 300-mile gas tank.

When you run out of electricity, it uses a gasoline engine to charge the battery. Its pretty much a “normal” car that happens to be able to be charged with electricity. Still got the $7500 federal tax credit too (Tesla is losing their credit, only $3750 right now, and it will drop again in a few months)

drfish
Guest
drfish

It will be interesting to see what the landscape looks like in 4 years or so. At the moment, I’m thinking a plugin hybrid, but maybe all electric will be the way to go by then. 100 miles of range would be enough for me 99% of the time, 50 miles probably 90%. Current 200-300+ ranges would be good enough for all but maybe one or two trips a year.

dragontamer5788
Guest
dragontamer5788

[quote<]100 miles of range would be enough for me 99% of the time, 50 miles probably 90%. Current 200-300+ ranges would be good enough for all but maybe one or two trips a year.[/quote<] Roughly the same calculations as me. 50 miles covers my typical working day, but it would be pushing it when I do errands after work. I'd estimate maybe 2 or 3 times a week I'd go over 50 miles (work -> groceries -> help my sister's kids -> home) 100 miles covers almost every use case I can think of, except for vacations (which 300+ range won't cover either). There's a bunch of plug-in hybrids with lol 20-mile electric range (Toyota Prius), but that's not even enough for me to go to work and back each day. 50-miles covers my typical daily driving behavior. So that's why I like the Honda Clarity / Chevy Volt.

drfish
Guest
drfish

The other thing I’m waiting for is something more like the formfactor of my beloved Rav4. I’m still driving a 2003 model and it’s a perfect fit for what we need. Ellie’s wheelchair fits great in the back of my Rav, but it wouldn’t fit in a sedan’s trunk. Similarly, I can put the dogs in the back of the Rav and keep them away from any of the seats, which are usually occupied by car seats for Ellie and Wren.

I don’t want a big honkin’ SUV or need a minivan, but I can’t get by without a [i<]bit[/i<] of extra space.

dragontamer5788
Guest
dragontamer5788

Hmm, Model X is around RAV4 size (slightly shorter but slightly longer), but its also a $100k vehicle. Yeah, its probably best to wait a few years. I know “Rivian” is building a “large skateboard” for various car manufacturers to use as a large electric car base. They’ve got contracts with Ford (and at least… used to have a contract with GM). There are a bunch of rumors about how their vehicles will look like, but nothing seems official yet. I think Rivian is going for large-SUV or truck market though. Not really the crossover size of a RAV4. Then… Read more »

shank15217
Guest
shank15217

Consider a Model Y, it comes out next year and has the space you seem to need. I would advise against plug in hybrids, their battery sizes are anemic and a few months down the line you will have buyers remorse, you have a fuel station at home, why would you ever want to visit a gas station again? I have gone through the journey you undertaking now including buying a hybrid.., it leads to a 100% renewable future. You will never look back.

dragontamer5788
Guest
dragontamer5788

Model Y doesn’t exist yet, and is being built on the Model 3 chassis. The Model Y will be taller than the 3, but we’re looking at an “SUV” that’s comparable to the Ford C-Max (built on top of the Ford Focus chassis). I dunno, maybe its worth looking into, but these “SUVs” that are build on top of a sedan chassis have always been noticeably smaller than a properly built crossover like the Model X or RAV4 (or a [b<]real[/b<] SUV built on a truck chassis, like a Chevy Suburban) The Model Y is clearly a smaller vehicle to compete in the C-max category, while the Model X is the proper competitor to RAV4 sized vehicles. Tesla is being careful to keep their vehicle lines differentiated. All indications seem to be that the Model Y will be noticeably smaller than the RAV4. Model X is Tesla's competitor to the RAV4 size.

drfish
Guest
drfish

That said, my old Rav4 is smaller than the new ones and it works just fine for us. Seriously, if I can fit the wheelchair in it, it will be in the running.

Plug-in hybrids will probably be a quaint memory in 4 years, that’s a fair point.

shank15217
Guest
shank15217

A rav4 is 182 inch length, a Model Y is ~186 inch length so CMAX is significantly shorter. X is 198.

UberGerbil
Guest
UberGerbil

Might be a little small for your needs but: [url<]https://www.caranddriver.com/hyundai/kona-electric[/url<]

drfish
Guest
drfish

Hmm, that has potential. Thanks!

shank15217
Guest
shank15217

You will find that they are very hard to find and buy in the US, especially in non carb states. Look into a Leaf + as well.

Leader952
Guest
Leader952

The thing about owning a Tesla no one talks about — nightmarish repair delays

[url<]https://www.msn.com/en-us/news/us/the-thing-about-owning-a-tesla-no-one-talks-about-%E2%80%94-nightmarish-repair-delays/ar-AAAJmmj[/url<] [quote<]How long would you say is reasonable time for an auto body shop to fix a car with light body and suspension damage? Two weeks? A month? Two months? Craig Hedges was driving on the Stanford campus on Oct. 27, 2018, when a Toyota Corolla pulled out from a parking space and plowed into his 2016 Tesla Model S. Neither vehicle was moving very fast, but the Tesla sustained front fender and suspension damage and wasn't drivable. So the Burlingame resident had it towed a few days later to Chilton Auto Body in San Carlos, the nearest Tesla-approved body shop and the preferred shop of his insurer, Allstate. Nearly six months later, his Model S still hasn't been repaired. The potentially long wait Tesla enthusiasts face to get their cars fixed after fender benders or worse damage is one of less publicized aspects of owning a Tesla. "When my car got in an accident, it was somewhere in the thirties to be worked on and the last time I had a conversation with someone there a few weeks ago, there was well over 130 Teslas there to get fixed," Hedges said. "Now I think if you're number 130, it's going to be well over a year to get your car back." [/quote<]

Gastec
Guest
Gastec

You’re not supposed to repair a Tesla but buy another one. Same as with Apple products.

Luminair
Guest
Luminair

Superb story

Prion
Guest
Prion

Is that a refundable federal tax credit?

drfish
Guest
drfish

Sadly, it is not.

tyr2
Guest
tyr2

FWIW: We installed a full-solar system on our central Fla home about twelve years ago; our intent had been to mitigate not obviate our electric bill. In an area where electric bills typically run $550/month annualized, ours hovers around $70 … occasionally, an odd month will be much lower. Over the ownership period, our installation has weathered hurricanes, hail, cyclonic-events (mild-ish–TBTG), may I repeat, nasty hurricanes … all without drama. It has already paid for itself, after the various inducements and tax allowances. Functionally, the HVAC gets a pretty thorough work out throughout the year. Much of a year “features”… Read more »

adampk17
Guest
adampk17

Is the extra weight of the solar panels a consideration one needs to investigate, particularly with a snow load too? Do the installers look at the construction of your roof supports during the quote process perhaps?

drfish
Guest
drfish

Part of the quoting process was to establish the age of the house, I assume part of that is to understand the building codes it was built to. None of the potential installers had concerns about my roof and the weight is distributed to a very low PSI.

Guest
ludi

Great article! Obvious that a lot of work went into the write-up and editing, and the information is presented in a clear, helpful way.

ca_steve
Guest
ca_steve

Very nice. You might look into replacing your gas furnace/electric cooling system with a heat pump based one. There’s still a federal credit for it..and some states also provide rebates/credit. As you are generating your own power during the day, some judicious time-shifting for household temp control could make it a speedy payback.

Also, I’m surprised by the macro inverters. I thought installations were all moving toward solid state micro inverters (better efficiency, longer warranties). What was the thought process from the installers?

drfish
Guest
drfish

Once I have a year of perspective under my belt, I’ll definitely be exploring those options with whatever power budget I have to spare. I’m going to work the system for everything it’s worth, I don’t want it to be overkill forever, heh.

I got the impressing that for an install my size the macro inverters were more cost-effective. TBH, I ran with a lot of their suggestions after confirming they weren’t completely off the mark. It’s all about balance/compromise with a project of this scope.

Micro inverters seemed like a [i<]great[/i<] way to get started if you wanted to do a smaller install, or just dabble a bit with the concept DIY-style. Easy to just add on a few more panels as needed.

Mark Nelson
Member

Damn fish, now I wanna marry you 🙂
This was a great article; solar power + drones= win win!

I would love to see more article like this; less common themes but super nerdy/techy.

drfish
Guest
drfish

Thanks man! Sadly, projects like this are inherently few and far between. I’ll continue to share what I can with everyone, though.

Leader952
Guest
Leader952

[quote<]The complete system cost $65,000. I've been planning on this for a long time and was able to pay $15,000 down. We got a home equity loan for the remaining $50,000. It's a 12-year loan with payments of $475 a month. Thankfully, that's not how things are going to go down. For one, and this is a big deal, there's currently a 30% tax credit from the feds that you can claim for solar projects. That works out to $19,500 in taxes that I don't have to pay until it's used up.[/quote<] Here are the totals from the costs you provide: $475 per month loan payment * 12 months * 12 years = $68,400 $68,400 + $15,000 down payment = $83,400 total cost $83,400 - $19,500 tax credit = $63,900 total cost for 12 years $63,900 / 12 years / 12 months = $443.75 per month ---- [quote<]My family-heavy electric bill averaged $350 a month last year, and in 2017 it averaged $275 a month.[/quote<] So even using your worst case numbers you are paying a [b<]Solar Penalty[/b<] of $93.75 per month or $13,500 over the full 12 years. If you used the $275 per month average from 2017 the [b<]Solar Penalty[/b<] would be $169.75 per month or $24,300 over the full 12 years. Your numbers also do not include any maintenance or repair costs nor any insurance premiums nor factor in the degraded power production during those 12 years. I live in Texas where the sun shines almost all the time and am currently paying 7.6 cents per KWh (on the last few months of a 24 month contract). When I renew it will be going to 8.4 cents per KWh for again 24 months. My home is all electric so heating/cooling is done via a heat pump and the water heater and dryer is electric heat. In 2017 I used 21.197 MWh (Mega watt hours) for the entire year or 1766 KWh's per month at a cost of $133.56 per month. In 2018 I was into Monero coin mining big time on lots of quad servers (each with 8-16 cores each CPU or 32-64 cores per server) doing CPU mining. My average power usage went to 5156 KWh's per month. Costs were $336.66 per month or 7.2 cents per KWh. My mining profits were actually higher than my power costs. So using even my insane numbers from 2018 I would still be saving $107.09 by not using Solar. Having residential solar is a money losing endeavor.

dragontamer5788
Guest
dragontamer5788

His system includes battery + associated costs (safety mechanism to disconnect power from the mains to protect electric workers). There’s a hefty premium you pay if you want to be self-sufficient when the grid goes down.

[quote<]Your numbers also do not include any maintenance or repair costs nor any insurance premiums nor factor in the degraded power production during those 12 years.[/quote<] Solar panels are expected to last for more than 12 years. [quote<]Your numbers also do not include any maintenance or repair costs[/quote<] Your numbers don't include deprecation (erm... more precisely... you're deprecating to zero too fast...). IE: your house is literally worth more money because you have solar panels on it. 10 years from now, he can sell his house for maybe +$30,000 or so because of these solar panels and recoup a lot of the costs. (Depending on how much technology improves however: there's risk here. If new solar panels come out that are more efficient, maybe it will only be +$20,000 to his home value 10 years from now) Where I got $30,000: Assuming a 20-year lifespan and a linear deprecation curve, his $68,000 system will be worth $34,000 after 10 years. Round down slightly because of advancements in the solar-panel industry. Obviously, this is just a spitball estimate, but its better than no estimate at all. The math isn't quite as simple as you make it out to be. And part of it requires a crystal ball to really figure out. In any case, once you factor in the increased value of the home... and ignore the "premium" battery backup system (totally a luxury item. Awesome, but its very expensive), its a pretty clear cut-and-dry case in favor of solar panels. Its just like any other big-ticket item on a house. If you replace the roof, you advertise that when you sell the house. When you replace the furnace, you also advertise that fact. One issue is that you narrow your pool of buyers by getting solar... (any anti-solar people will stay away from this house now)... but I think there has been enough of a cultural change to take that risk long term now (there are probably more people who'd see solar as a net-benefit rather than a detriment, and willing to pay for the house when the time comes).

TurtlePerson2
Guest
TurtlePerson2

You’re right that he’s being a bit rosy in the financial calculation, but he’s upfront about the fact that there is an intangible benefit that he gets from the system that makes it worth it for him. And as dragontamer has mentioned, you are neglecting the fact that the system is itself an asset and has considerable value after the payoff period is over. Even once he stops making payments he will continue to have “free” electricity. Your basic conclusion that residential solar is not yet cost effective is true, but I think that this article shows how close it’s… Read more »

Leader952
Guest
Leader952

[quote<]Also, are you sure about your 7.2 cents rate? Where I live in Dallas, the delivery charge is 4 cents or so by itself. Some power companies sell you a rate like 7.2 cents, but when you actually look at your bill, it's a good bit higher because of delivery charges.[/quote<] Yes the 7.2 cents per KWh is correct. The total cost of my electric bills over the twelve months of 2018 (which includes ONCOR distribution charges and any taxes and fees) was $4425.64. Dividing that cost by 61,866 KWh's of use results in 7.15359 cents per KWh which I rounded up to 7.2 cents per KWh. I have used a spread sheet since 2004 that tracks my costs per year and per provider. On March 22 of 2017 I renewed with Source Power & Gas at these rates: Renewal Date: 03/22/2017 Plan Name: Source Secure Fixed 24 Contract Start Date: 06/13/2017 Contract Expiration Date: 06/13/2019 Average Price: 7.0¢ per kWh (based on 2000 kWh per month) Term: 24 Months Energy Charge: 3.452¢ per kWh Monthly Fee: $14.95 per bill cycle if < 1,000 kWh or $0.00 per bill cycle if ≥ 1,000 kWh TDU Charges: $5.25 per month and 3.286¢ per kWh (As noted on EFL, TDU charges are subject to change.) Source Power & Gas stopped offering residential plans a few months later but had Cirro take over the plan that I signed up for without any changes. Turned out to be a great deal since electric rates were at an all time low then. What is funny is that the Oncore charges have gone down the last few months and I am now only paying 6.9 cents per KWh. Bill Date: 03/20/2019 1799: KWh's Used $59.82: ONCOR Charge $62.10: Cirro Charge $2.43: Taxes/Fees $124.35: Total Bill $0.069: $$$ per KWh April 2019 was also at 6.9 cents per KWh. Bill Date: 04/18/2019 1877: KWh's Used $129.58: Total Bill $0.069: $$$ per KWh

drfish
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drfish

My math is my best guess, but you missed a couple factors. The biggest one is that I have no intention of taking 12-years to pay off the loan. I mentioned that I expect to do it in 4, that will save a lot of cash (there’s not early payoff penalty). Also, it’s highly likely the electrical costs will rise, but that’s hard to account for precisely.

Leader952
Guest
Leader952

But you also forgot these costs: Your numbers also do not include any maintenance or repair costs nor any insurance premiums nor factor in the degraded power production during those 12 years.

Also using cash to pay down the loan early does save on interest but then you lose on what that cash would have earned if invested.

drfish
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drfish

I’m just presenting my best guess, I think there are too many factors for me to offer a more accurate estimate. Increased insurance cost was only $140/year. I should have the system oversized enough that degradation won’t come into play financially, but again, I won’t be able to predict that more accurately until I have at least my first year with the system completed. I’ve already padded the estimates I was given by a couple years. Maintenance and/or repair will cost something, hence providing a range for ROI instead of a firm number. Then again, I’ve got a good, long… Read more »

dragontamer5788
Guest
dragontamer5788

[quote<]12 years[/quote<] If the system lasts 30 years, then he's literally got free electricity 18 years longer than your 12-year estimate. [quote<]Also using cash to pay down the loan early does save on interest but then you lose on what that cash would have earned if invested.[/quote<] S&P 500's PE Ratio is [url=https://www.multpl.com/s-p-500-pe-ratio<]22.13 at the moment[/url<], which means it will take 22.13 years before the typical S&P500 company makes profits equivalent to the price you payed for the stock. (If you spend $1000 on stocks, it will take 22.13 years, at the current rate, for $1000 of profit to be generated from your equity). Solar Panels will prove to be a better investment than the S&P500 as long as they make a profit before 22.13 years. The PE Ratio is a very good indicator of bubbles and crashes. If stocks rise far above their profit-making abilities (or: if the profit-making abilities of companies crash), then the stock market usually falls as a result. Historically, the S&P 500 has a ~15 PE ratio or so, so the 22.13 PE Ratio is a bit high.

Leader952
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Leader952

30 Years!!!

Who can guarantee to live in the same home for 30 years?
Who never moves?
Who doesn’t change jobs and have to move across the country or another city?
Who doesn’t start a family and outgrow their home?

dragontamer5788
Guest
dragontamer5788

[quote<]Who can guarantee to live in the same home for 30 years?[/quote<] When you spend $68,000 on equipment that's expected to last 30 years, it means that 10 years from now, its still worth $40,000+ or so (subject to local real-estate conditions. Consult with real-estate specialist to understand your local conditions). $68,000 is a rather substantial home improvement investment, so really, it depends on your neighborhood. If all the homes in the neighborhood are $500,000 or so, then maybe +$40,000 for a 10-year old solar array isn't that big of a deal. But if the other homes in the neighborhood are all $200,000, then its a hard sell to try and sell your house for $240,000 because of the solar panels. You don't want to "over-improve" your house above and beyond what your neighborhood can support. That's the thing about long-lasting equipment. You [b<]sell it to someone else[/b<] when you're done with it. No one actually uses the same equipment for 30 years, it gets passed around. ------ Bonus points: there are a **TON** of tax games you can play with home-equity lines of credit. You can dramatically play the tax game and reduce your federal income tax significantly if you play things right.

drfish
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drfish

Of course I can’t guarantee I won’t need to move, but I certain intend to try and stay put. I figure there’s higher odds that we won’t move than that we do.

e1jones
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e1jones

[quote]Having residential solar is a money losing endeavor.[quote] … For You. Lol, congratulations on having cheap electricity? Here in sunny San Diego my solar systems, via PPA, are currently $.17x/kWh. Meanwhile the investor owned utility monopoly has a base rate of $.21-.23/kWh (depending on the month), though the base rate is only for the first ~350kWh/month (again, variable by month). With solar, I’ve never gotten past the first tier. Once you get past that, the next tier is $.40-.43/kWh up to ~1100kW/month. After that every kWh is $.48-$.50/kWh. Now, with both systems running, I’ve saved over $100/month on average (2018:… Read more »

Leader952
Guest
Leader952

Having residential solar is a money losing endeavor. For me and a heck of a lot of others who have gone that route.

I noticed you provided no details on your financial costs for going solar.

The fact that you state that you save $100/month on average without stating what the financial costs for going solar were means that your savings data is flawed and useless.

bandannaman
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bandannaman

Friendly feedback: You could have phrased that as: “Can you provide details on your financial costs for going solar? It’s hard to tell if we’re comparing apples to apples on that $100/month, and I’m skeptical.” instead of the verbal jabs.

e1jones
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e1jones

I provided all the necessary info, actually. By their very nature, PPAs have no up front cost. I also mentioned what I’ve saved in the 2 full years since moving to 2 solar systems, which averaged across 12 months, is a little over $100/month. I have a spreadsheet where I’ve tracked the power provided by solar, the cost of said power, power from the utility and what it cost. This is also used to calculate what I would have spent based on the published monthly kWh tier allotments and the price at each tier. Last year I paid ~$30 at… Read more »

derFunkenstein
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derFunkenstein

This is so cool. I’ve daydreamed about a solar house in the past, but we’ve got two really big trees in the back yard, which faces west. They keep the temperatures down in the summer and provide a nice wind block in the winter. I’d hate to give those up.

XTF
Guest
XTF

Do you use electricity for both heating and cooling? 25 MWh seems like a lot.

Our electricity usage is 5 MWh yearly for two people. Cooking and heating are gas-based, no need for cooling (in the Netherlands, Europe).

derFunkenstein
Guest
derFunkenstein

Cooling is electric, but our furnace, stove, and dryer are gas. From December to March, we averaged around 33 kWh per day. Now that the furnace is off, we’re down to around 22 or so. That includes me being a full-time telecommuter. There’s always lights and PCs on during the day. Over the last two weeks, the only times we’ve broken 25 were two days where the furnace ran because the high was in the 50-55 F range. Ameren just replaced our electric meter, and so now we get much more immediate and granular information on their website. It’s fun… Read more »

moo
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moo

These sorts of long-term, house-related projects tend to [financially] fail miserably, at least around here — I’m in the Toronto area. I bought my first house about 8 years ago. Buy a hot water tank, or rent one. I did the math. Buying one would break even after 9 years, basically feeding me $40/month thereafter. Tanks last 15-to-20 years, so it was well worth it, on paper. As luck would have it, my friend also bought a house that same year. His already had a fully-owned hot water tank. It was already 9 years old. It was perfectly good. But… Read more »

blastdoor
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blastdoor

All very true…

Similarly I would advise people to never have kids and never fall in love. So much can go terribly wrong.

derFunkenstein
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derFunkenstein

Getting out of bed in the morning is perilous. You could slip on a sock, fall, break your nose. Just not worth getting up.

moo
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moo

And that’s why we pay a lot of money to insure against those very things. Doing so gives us the freedom to take those risks as a matter of routine. We drive cars that cost more than we can save in three years of discretionary income, purely because we don’t worry about damaging to it nor to us. But to your point, how much money would you put down as a bet that you won’t break a bone (slipping on a sock, or onto your nose) over the course of the next 10 years? Personally, I’d probably be willing to… Read more »

moo
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moo

You have kids planning to spend money, not save it, and planning to have more problems, not fewer. You don’t have children as an investment in elderly care. As for falling in love, we’re long past the days (here at least) of falling in love as an investment in having your needs met. Instead, we fall in love to have company through tragic times. It’s never cheaper, it’s never more freedom, and it’s rarely (in terms of days per year) better. But it remains very much worthwhile at the extremes (both good events and tragic ones).

Waco
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Waco

[i<]blink[/i<] Keep your chin up. Love may be hard to find, but it's definitely worthwhile when you do. Sure, there are a few downsides, but the positives far far outweigh the cons.

Kretschmer
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Kretschmer

At least falling in love has upsides. Kids? Ehhhhh..

moog
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moog

Do you mean MGTOW? I agree.

drfish
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drfish

Hence why I started the story how I did. Those are risks I’m willing to take.

TurtlePerson2
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TurtlePerson2

It’s funny how you start the story with the disclaimer that you know the whole thing isn’t the best investment you can make from a mathematical perspective and then in the comments everyone piles on about how it’s not a great investment from a mathematical perspective.

drfish
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drfish

Welcome to the Internet, you must be new here. 😉

moo
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moo

That’s not fair. One paragraph about dreams, followed by five pages about math. You’re shocked that there’s feedback about the math? But it’s more than that. Your dream (as I understand it) was never to build it, and then promptly have it destroyed. Your dream wasn’t to have it for a year, and then move away. Your dream (again, as I understand it) was to have it persist for a significant portion of your life, and even for your daughters’ lives. If, as a result of some failure, it vanishes in 3 years, then that sucks. It has nothing to… Read more »

drfish
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drfish

Oh, I’m not shocked. I should have explained a couple things better, though. Namely that really bad things will be covered by homeowners insurance and that slightly less bad things will be covered by the 10-25 year warranty on the various parts of the system.

Guest
ludi

If that homeowner can’t be troubled to scare the birds by washing the nests out in early spring around the same time when they clean the gutters, then they’ve probably made peace with the upstairs neighbors.

As for the other, pigeons aren’t woodpeckers. The acidity in their poop will certainly degrade the roof at an accelerated rate, but that goes back to the evident unwillingness to chase the pigeons out periodically.

moo
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moo

Oh, hey, if we’re spending $65’000, and are willing to handle more work as a result, then that’s very peaceful. But as usual, if I were willing to work another hundred hours a year on home projects and bird shooing, I’m sure those 100 hours could be put to lots of things that give me more joy than electricity. Bullshit pigeons don’t peck, and scratch. By the way, woodpeckers peck to create sound and eat bugs, not to dig out wood. But none of this matters. Birds build their homes. If their home is five inches between panels and shingles,… Read more »

cygnus1
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cygnus1

Every action we take is a gamble, anything can go wrong at any time…. doesn’t mean stop breathing because you might have a pulmonary embolism.

Anonymous Coward
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Anonymous Coward

The uncertainty of life does not mean that all actions have equally unknowable outcomes.

ptsant
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ptsant

You make good points. There are a few additional advantages to having solar: 1. You are doing something (probably) good for the planet 2. Cool gadgets 3. Synergy with electric car: will conveniently store energy when surplus is produced, thus being practically free to use, if your power budget is sufficient For all the reasons that you mention, I wouldn’t advise this as an investment for people who are short on cash or need to first deal with other priorities. But if you have a decent income, live in a sunny area and do this the right way there is… Read more »

Anonymous Coward
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Anonymous Coward

I have to agree that a lot can happen in 10 years.

I have some inlaws with what looks to be a similarly large solar installation, they had some major component (an inverter?) fail out of warranty, I don’t know the specifics. The replacement cost was considerable however. Wish I could remember what it cost them, but I’m thinking it will have added some years to the payback on the system. There is a good chance they shot themselves in the foot buying too cheaply.

cygnus1
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cygnus1

[quote=”drfish”<]The same lack of shade that makes my house good for solar also makes it a bear to keep cool. [/quote<] Now that the panels are on the roof, covering a large majority of it and providing a small air gap between where the sunshine is hitting and the roof materials, do you know if that will provide any reduction of heat absorption in the roof? IE, make it slightly cheaper to cool during the summer? And conversely, making it slightly more expensive to heat in the winter?

drfish
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drfish

That’s a popular question, and one I will definitely try to quantify in a follow-up piece. It sounds good in theory.

cygnus1
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cygnus1

Right on. Also thanks for this article, I’ve definitely been thinking about solar on our next house and this is a really good write up on a complete system with battery.

Mr Bill
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Mr Bill

I’ve wondered about this also. My business is in a metal condo and the AC cooling of it in peak summer runs between $650/mo to $850/mo during the summer. The idea of cooling the panels for summer and conversely at need warming them enough to melt snow in winter is interesting. But it must be weighed against the net improvement in performance during both seasons. The summer cooling seems like a win if you need the hot water. In the southwest it gets cool at night and I knew one guy that used it to heat their swimming pool, summer… Read more »

TurtlePerson2
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TurtlePerson2

Solar panels usually get pretty hot because they’re trying to capture as much light as possible and convert it to electricity. The efficiency of the process is fairly low and as I understand it, solar panels get hotter than shingles. One of my old coworkers actually created a startup based around the idea of piping water through the panels. The idea is that you need to heat up water anyway and you want to cool the panels anyway, so why not take the excess heat that you don’t want from the solar panels to become the heat you do want… Read more »

liquidsquid
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liquidsquid

That is an excellent thought. Up in the Adirondacks is a cool museum
[url<]https://www.wildcenter.org[/url<] Where they have a solar heat transfer system with evacuated chambers to convert solar to hot water very efficiently even when it is very cold outside. Poke around on the website and I'm sure you can find more information. You could probably Gerry-rig something yourself using the same materials as used for sub-floor heating and heat-exchangers, if only to pre-warm water before it enters your water heater.

Captain Ned
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Captain Ned

There was a time when “solar” meant exactly that, i.e. using the sun to heat a liquid heat transfer media. Used to see lots of those on roofs in the ’70s/’80s.

Guest
ludi

A lot of gunked-up plumbing and rotted roofs as a result, which is why you don’t see many of them now. The materials science of that day wasn’t quite up to the task.

I imagine that a modern stainless steel system with appropriate silicone tubing would work a fair bit better but the plumbing is still more of a wildcard to install and maintain than the electrical wiring.

meerkt
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meerkt

It’s been popular in some countries since the 60s, maybe 50s:
[url<]https://en.wikipedia.org/wiki/Solar_water_heating[/url<]

tanker27
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tanker27

This article is so awesome! Makes me want to take the leap!

TurtlePerson2
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TurtlePerson2

Thanks for documenting your experience. I grew up in Michigan, but now live in Dallas and have always been curious about solar roofing. I’m curious about your electricity costs though. It’s only my wife and I in our house, but my electricity bill rarely goes north of $200 even running the AC from 100+ outside to 72 inside. Here in Dallas, we have the issue of hail damage. You have what seems like a one-in-twenty chance of having roof damage from hail in any given year (maybe even worse than that). Still, Dallas does get a lot more sun than… Read more »

drfish
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drfish

We got our PMI removed from our mortgage payment shortly after the panels went up. The value of our home had gone up enough without the panels that it we could have gotten it removed regardless, but what was interesting is that there was a cap on the value the appraiser could use for a solar panel system, just $28k.

tanker27
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tanker27

the better question might be, what is the lifespan of current tech panels/ whole system? and the associated warranty.

drfish
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drfish

Essentially, I’m covered for 25 years and hoping for 35. The battery is covered for 10 years, with an LG-specific warranty on the capacity of the cells, which is nice.

tanker27
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tanker27

25 Years…..That’s a pretty darn good lifespan. I’d assume as wear and tear set in you’d be replacing what is needed al carte.

cjcerny
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cjcerny

What does the panel maker say about hail resistance?

drfish
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drfish

The panels are not warrantied for hail damage, but my home insurance covers it.

morphine
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morphine

If hail damage happens a few years down the road when the panels start losing efficiency, it might actually benefit you if they break 🙂

Guest
ludi

Only a net benefit if hail is extremely rare where you live. My state, Colorado, is second only to Texas for major hail events (thanks, Rocky Mountains!). Three of this state’s top-ten costliest storms took place between 2016-2018. The effect of that on homeowner and automotive insurance premiums has been almost as catastrophic as the storms.

So yeah, your stuff will get repaired/replaced, but you’ll still pay for it in the long run.

cygnus1
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cygnus1

Yeah, that’s basically how insurance works. It’s spreading the cost of negative events across everyone buying insurance for that kind of thing… while letting the middle man make a nice profit.

The Egg
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The Egg

Thoroughly enjoyed this read. Once the zombies come, I’ll have to put on my full-kevlar motorcycle outfit (so their bites can’t get through) and somehow make my way across the lake to help set up TR resistance headquarters.

You shouldn’t have to worry too much in the winter (they don’t have any body heat, so they’ll freeze solid), but I’m wondering if something like a leaf-blower on a pole could clear light, powdery snow?

drfish
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drfish

Believe it or not, a rail-mounted leaf blower is on my list of crazy ideas to give further consideration too. I have to be careful not to do anything to clear off the panels thay may void the warranty though. Hence the plan of just having so much that it doesn’t even matter if they are covered for 1/4 of the year.

Chrispy_
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Chrispy_

As someone who doesn’t really care about gardening, are there any real disadvantages to putting a large array at ground level – say on a permanent scaffold about 2′ off the floor?

I’d imagine they’d be easier to maintain/clean if they weren’t on a roof and it’d make roofing maintenance a lot less hassle.

drfish
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drfish

There’s a cost associated with building a framework for ground-mounted panels that is less for roof-mounted ones. Also, shade is a bigger problem because the house itself will block the panels in many locations.

My roof is new enough that it should last as long as the panels and, by all accounts, the section of the roof under the panels (most of it in my case) won’t see much wear because the panels are protecting it.

liquidsquid
Guest
liquidsquid

Actually that is far preferable in most cases, and what I plan to do. Installation costs less, it can be more easily maintained, and you don’t have to get on the roof. The drawback is if you have a long run between the array and the house, the copper can be pricey. Something to seriously consider is protection from hail. On ground level, you can quickly drape some protection over it. On a roof? Much more difficult. No plan here to spend $65K on a system, but I am sure a big chunk of costs is the battery backup and… Read more »

blastdoor
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blastdoor

I love this article and would love to do this too. I’d love to take advantage of the federal credit but can’t swing it right now. Maybe the credit will return, though, or maybe technology will improve the economics so the credit isn’t needed.

Anyway… great article, and I’m jealous!

Kougar
Guest
Kougar

Awesome, very thorough article that was a great read! And a big thanks for that solar irradiance map!! I honestly was unable to find it without knowing the keyword. Given AC cost is such a huge part of a Texas electric bill I am curious how a roof of solar panels affects the house temps at the peak of summer, I’d imagine there would be some extra savings there even with just a small air gap under the panels. Will watch for your follow up articles! How safe is the installation from power grid surges, such as nearby lightning strikes… Read more »

drfish
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drfish

Good question! I neglected to mention that I did add the solar power system to our homeowners insurance. That cost $140 annually and it covers hail damage too, which isn’t covered in the panel’s warranty. Lightning is still going to kill anything it hits, that or it will now send my house back in time, I’m not sure which.

Also, yeah, that map was hard to find. There are a lot of others out there but I think that one was the most practical.

Leader952
Guest
Leader952

Just an FYI for those who live in Texas you can go 100% Renewable via NEW POWER TEXAS at 9.2¢ per KWh:

[url<]https://newpowertx.com/EmailHTML/efl.aspx?RateID=413&BrandID=5&PromoCodeID=0[/url<]

dragontamer5788
Guest
dragontamer5788

Strange. Power is quoted in my state by generation costs. Delivery costs aren’t included. I guess Texas quotes power with generation+delivery costs. Anyway, it should be noted that many states do offer the customer a “choice” in where your electricity is generated. In practice, the local utility is simply divying up the money that all of its customers have set their generator to. Supporting renewable power by simply changing the “origin” of your electricity costs absolutely nothing, and may be cheaper depending in your area. Its definitely a great idea if people aren’t aware of this relatively cheap option to… Read more »

TurtlePerson2
Guest
TurtlePerson2

The link states that this is the generation cost only and not the delivery cost. Where I live in Texas my delivery provider is Oncor and they tack on another 4 cents. The generation cost for this 100% renewable is roughly the same as my generation + delivery cost for my 10% renewable.

Leader952
Guest
Leader952

The link does not state the explicit Oncor costs of $0.0331 per KWh but it is included in the $0.092 per KWh quote.

See this quote in the link:

[quote<]The average price above only includes the costs for electricity generation, regulated charges from the applicable TDU for transmission and [b<][u<]delivery charges for service to Customer’s ESI ID[/u<][/b<] at 9.0¢ per kWh, and a base charge of $4.95 per billing cycle[/quote<] [url<]https://newpowertx.com/EmailHTML/efl.aspx?RateID=413&BrandID=5&PromoCodeID=0[/url<]

CScottG
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CScottG

Very Cool!

-question:

It looks like you have *surface-area (other than your roof) that’s just waiting to be used.

Did you consider any of the thin-film panels that are much less expensive (on perhaps an inexpensively/DIY erected car-port/front walk-way/patio-cover)?

*of course thin-film panels require considerably more surface area for a similar wattage-result.

drfish
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drfish

I did not, though I used to carry a small sample of one around in my wallet like ten years ago, heh. It simply didn’t come up with the quotes that I got.

I did talk about placing the panels in locations other than the roof but the cost of hardware and installation goes up a lot if you want to put them in your yard instead. Plus, the section of my yard that would be the best candidate for them is fairly small and putting them there would not have been neighbor-friendly.

liquidsquid
Guest
liquidsquid

That is interesting in increased cost in the yard, I have heard the opposite, but maybe things have changed. What I have seen is a single assembly that looks like bleachers that holds all the panels. Very simple. Of course our “yard” is rather large at 16 acres, so no neighbors to annoy.

Wirko
Guest
Wirko

Are the south-facing roof and the south wall (left & right of the door) too small to even bother considering? In the winter when the sun is lowest, four vertical panels on the wall could contribute a substantial part of total energy.

drfish
Guest
drfish

Yeah, I asked. It was going to be worth the labor of running wiring to them. I was also curious about the south facing roof of the shed in the yard, also a no-go for the same reason. Panels are “good enough” that you don’t need to bother with perfecting the angle anymore, I guess.

CScottG
Guest
CScottG

..yeah, I think as far as estimates go in North America – that thin-film is pretty hard to find. Funny-enough, some thin-film designs are a lot more efficient than they used to be and are even mono-crystalline. They can also react better to heat and are far more durable against things like hail. First Solar makes them in large batches for “grid” use. Series 6 is there latest, but good luck finding it for anywhere near what they charge power co.s for (..though not too surprising considering their orders on the previous Series 4 won’t be completed for 2 years).… Read more »

drfish
Guest
drfish

That looks awesome, but we get some [i<]wicked[/i<] winds thank to being in the middle of a big field. I'm comfortable with the panels on the roof, but I'd be less so with them one a homemade structure, not to mention snow load concerns.

CScottG
Guest
CScottG

Big expensive KITE! (..lol.)

(I was also thinking they would be angled (for run-off and for best sun exposure) rather than the flat structural roof-look of the pic.. with likely some sort of modest integrated gutter. Snow would be a killer to anything less than that.)

Kind’a like this one (with more than double the 20kWh total.. I guess that would be “spares”); sure pays to buy in bulk:

[url<]https://www.alibaba.com/product-detail/110W-ETFE-flexible-thin-film-solar_60839640061.html?src=sem_ggl&mark=google_shopping&src=sem_ggl&mark=shopping&cmpgn=1783478627&adgrp=70991558844&locintrst=&locphyscl=9027677&ntwrk=u&device=c&dvcmdl=&position=&pla_adtype=&pla_mrctid=129192273&pla_channel=online&pla_prdid=60839640061&pla_country=US&pla_lang=en&pla_group=301443531283&pla_localcode=&gclid=EAIaIQobChMIn5b4gL7l4QIVCbnACh1GuQy5EAkYBSABEgKF6_D_BwE#shopping-ads[/url<] -still, it would be tough to find an integrator wanting to do it with pre-purchased items (unless they just had a flat-fee arrangement for the install.) Even in bulk, the price seems like a misprint.

Audacity
Guest
Audacity

How does buying solar panels compare to putting the $65k in a index fund and just pay for grid electricity?

blastdoor
Guest
blastdoor

The index fund has a higher expected rate of return.

But, the return on the solar panels is more certain because you will get electricity from them. A financial crisis and stock market crash won’t affect the panels.

So the panels are financially similar to treasury bonds.

drfish
Guest
drfish

I’ll add to this a reminder that I was not purely financially motivated. The math checks out, but if profit is your [i<]only[/i<] goal, instead of just the primary one, there are certainly better ways to earn it with the same investment.

blastdoor
Guest
blastdoor

Good point, and I agree. I’d love to do this, but my motivation is more than $$.

And there’s nothing wrong with that! Heck, most of the things I spend money on are for enjoyment, not for ROI. If spending $65k on solar would prevent me from wasting that $65k on alcohol, then it’s money well spent!

Audacity
Guest
Audacity

My point is that not properly “benchmarking” the financials is a missed opportunity. You give vague pay-off points, but don’t compare it to where I usually keep my savings (i.e. stocks and bonds). Yes, you get electricity each month, and that is worth some money, and you get tax incentives. So compare the scenarios. If you were to take that money and put it in a relatively safe investment (say, a S&P 500 index fund), how does that play out over time if we assume that the performance of the fund will be similar to the long term average of… Read more »

drfish
Guest
drfish

Sorry, that was just beyond the scope of this. I’m not a financial adviser, I’m just a story teller. I need to see a few more bills before I really know what’s up. There’s a bit of disruption that happens when net metering is first setup and the dust hasn’t settled yet. I’m not sure if I will owe the power company $7/mo or not for my connection cost quite yet. I actually get an Excel spreadsheet emailed to me that tracks my credits and it looks like the credit may apply to all charges, not just power costs, but… Read more »

Audacity
Guest
Audacity

I don’t want my criticism to sound harsh – I really did enjoy your piece. It’s just the questions that were in the foreground of my mind while reading the article weren’t addressed, so I thought I’d interrogate you about them. 🙂

Cheers!

drfish
Guest
drfish

No worries, it’s a fair question. It just isn’t my area of expertise or my only concern.

liquidsquid
Guest
liquidsquid

Don’t forget an index fund does not get tax incentives either.

TurtlePerson2
Guest
TurtlePerson2

If solar panels were economically feasible by themselves, then any uninhabited land would be covered with them by the landowners who would sell the power to the utility. Note that the decreasing government subsidies are evidence that solar is becoming more and more cost effective. I wouldn’t be surprised if we see a tipping point in the next decade where all new construction uses solar shingles.

liquidsquid
Guest
liquidsquid

Actually that is happening all around us. Solar farms going in like crazy. One proposed one in Farmington, NY is going to be 40 acres. That is a LOT of panels.

ptsant
Guest
ptsant

He didn’t have $65k in cash to invest. So, he would be investing $15K in an index fund plus whatever he pays per month for the loan.

Also, you don’t get tax deduction for your index fund if it’s not part of a retirement plan. At least here. Don’t know about the US.

Krogoth
Guest
Krogoth

[url=https://www.youtube.com/watch?v=2pqKiOZdI40<]Praise the Sun![/url<]

Ummagumma
Guest
Ummagumma

I agree with the other comments on the “cool factor” of this article. I hope any follow-ups retain the “cool factor” and are very informative. Perhaps this is covered elsewhere in these comments, but could there be some coverage concerning the Internet requirements of this system (bandwidth needs, access methods, etc.) … since it obviously “calls home” (you can present a public webpage of your data on a 3rd party portal)? Is the “calling home” feature a non-negotiable requirement of this product? If the “calling home” feature is a non-negotiable requirement to use this product, has the manufacturer posted a… Read more »

drfish
Guest
drfish

The system will generate power without an internet connection. Mine is connected via Ethernet that the electricians ran as part of the install, but it also supports WiFi. It’s not FOSS, but you can enable API access in the portal so you could fiddle with your own or 3rd party apps. I won’t be happy if the portal goes away in whatever amount of time, but on my list of priorities, losing access to the portal will be WAY lower than if SolarEdge folded and my warranty became worthless. That said, the panels and battery will happily work with any… Read more »

ozzuneoj
Guest
ozzuneoj

This is a really cool article, but I can’t believe your electric bills are $350 per month at times. With five people in a 3 three story (100 year old) home in a frigid little town on the PA\NY boarder, our electric bills hit an absolute peak of $200 when it is below zero (*F) for a month and we are basically leaving everything running and supplementing with lots of electric heat. During most months the electric bill is under $100. Strange as it may seem, we’re all home most of the time too since two people are retired and… Read more »

drfish
Guest
drfish

Well, the $350 average was when we had 12 people in the house, heh. Eight of those 12 had their own PCs fired up much of the time too. It was rough.

Right now, we’re a family of four with my nephew living with us as well. That leaves us with an average whole-house power draw of about 1600 W continuously (without the AC). It probably works out that we have a few PCs running at all times, a compressor [url=https://www.phc-online.com/Nebulizer_Compressor_p/PMI7050.htm?click=102243&gclid=CjwKCAjwzPXlBRAjEiwAj_XTEZALtbnN7JGTHQPPg-DfbHyi5UKHZLDyt-J_sGz78NfHt_OTy8yuDRoC5YMQAvD_BwE<]like this[/url<] that draws 250 W ~16 hours a day to keep our daughter's trach humidified, a very active 1/2 HP sump pump, a furnace that's set to circulate, quite a bit of so-called vampire power from various electronics, an electric oven, the fridge... A couple loads of laundry and a load of dishes every day. It adds up. Heat, drier, and water are all gas.

godforsaken
Guest
godforsaken

Assuming you have a surplus of energy, and will lose your credits due to expiration, are you planning on changing your gas powered appliances to electric? (remember to take into account the future draw of your electric car(s) before you do this)
and will you be proactive or reactive when doing this?

drfish
Guest
drfish

The short answer is maybe. I’m not going to make any major changes to my electrical consumption for an entire year, then I’ll see what kind of surplus I have to work with after that. I’d like to burn as little gas as possible, but not at the expense of resurrecting my electric bill.

That said, an on-demand hot water heater is on my shortlist. Also, my wife wants a hot tub and I’m getting back into aquariums. So, like I said, I do plan to use more power than I am right now.

JustAnEngineer
Guest
JustAnEngineer

You should be finding out what your maximum daily and weekly production can be in the next six weeks. That doesn’t tell you how low it will go in the winter, but it provides an upper bound.

Geoff Gasior
Member

Depends on may factors. Type of construction, where you live, appliances (meaning heating/air conditioning systems applied), your usage patterns and price charges by energy companies you have. It is not unheard of in the Central Valley in California to have 4 to 5 hundred dollars a Electricity bill because your air conditioner is running 24/7 in the summer. When I owned a large home out there it was quite common to have 30+ days in the summer to be over 100 degrees during the day. My average bill was between 3 and 4 hundred dollars per month because you had… Read more »

Aether
Guest
Aether

Great article, and thanks for posting the links to relevant info!

shaq_mobile
Guest
shaq_mobile

How does the yearly loss of panel effectiveness impact roi? .5% a year seems huge

drfish
Guest
drfish

Based on what I know, my 20 kW system would be down to about 18 kW after 25 years. A bummer, but not exactly tragic. That’s about equivalent to six of my panels ceasing to function. If things pan out as I hope they do in my case, I’ll still have plenty of headroom and it won’t change the ROI at all. So hard to predict how much power I’ll be using that far out though, heh.

TheEmrys
Guest
TheEmrys

As panels increase in efficiency, with all of your infrastructure in place, you could very well spend a little bit and replace a couple of panels and get right back to where you were. Well, if you find that it dips you below where you want to be.

TurtlePerson2
Guest
TurtlePerson2

Solar panel efficiency has been improving very slowly. We are talking about doubling in the last 20 years. What has been decreasing more rapidly is cost.

Zizy
Guest
Zizy

Nah, it is even worse than you state – it is not even close to doubling:
[url<]https://www.nrel.gov/pv/cell-efficiency.html[/url<] From 2000 to now, we improved about 2% for the typical doped c-Si solar cell = improvement of ~10%. You need to compare current stuff to the ones from 1977 to claim doubling - but this is more than 50 years. There is no magic to enable simple silicon to reach above 29% - you require tandems or concentrators to get above that. As for price drops, that is the best reason to NOT get PV, unfortunately. We are getting close to the tipping point where PV's ROI gets too good to not invest. At that point prices of electricity start dropping due to many PV plants => sinks most older investments.

Anonymous Coward
Guest
Anonymous Coward

Will the prices drop, or will new uses step in, for example electric cars?

I’d rather expect prices to rise due in part to electric transport, but also as effort is made to step away from fossil fuels for electricity generation, will I suppose requires some expensive infrastructure to sufficiently cover low generation periods.

dragontamer5788
Guest
dragontamer5788

My expectation for the future is for subsidies to slowly subside. Not just the tax-credit for installation of panels, but net-metering is [b<]inevitably[/b<] doomed. The economics simply do not support net-metering in the long run. In the future, people will be paid wholesale prices (at best) for the electricity that they generate, which may be negative-cost in some areas. When the electric grid suffers from overgeneration, pumping more electricity into the grid may cause a fire (!!) As such, the "realtime" price of electricity reaches [b<]negative[/b<] during those overgeneration periods. California is beginning to see these kinds of effects. In the future, the "price" of 1pm electricity will be lower than the price of 8pm electricity (especially as more solar installations show up). At that point, the 10kW-hr battery pack can be used to "energy arbitrage", to maximize the price of electricity you sell to the grid, and minimize the price of electricity that you pay for. So its a bit of a forward-looking investment (its not super useful right now, but might become handy 10+ years from now, if solar becomes more popular). I don't know how the electricity prices will be negotiated in the future, but power-meters continue to grow more and more advanced to support this kind of "smart grid" (more pricing information to be sent with the electricity, so that home-devices can make decisions) ----------------- Net-metering may continue to exist [b<]IF[/b<] local governments invest strongly into energy storage technologies. If the local government's energy storage (Pumped Hydro, Battery-Energy Storage, and other energy-storage mechanisms) are sufficient to keep net-metering available, then it will last longer. At the end of the day, these programs have to make money if you expect them to keep going. Net metering loses money, so its inevitably going to fail eventually. By "eventually", I mean over the next 20 years. Its a long-term statement of mine.

Anonymous Coward
Guest
Anonymous Coward

Yeah I’d like to see the price of electricity follow supply and demand at high resolution, its best to minimize how much people can ignore reality. Ignoring reality tends to create greater environmental problems than working with reality.

cegras
Guest
cegras

Excellent article. You mentioned that the solar panels won’t do much in the winter. Are there options for solar panels with integrated heaters? Since they would be generating their own heaters, I imagine that it might be a good defense for keeping the panels clear of snow, if the snowfall is not too heavy.

DavidC1
Guest
DavidC1

You might want to just clear the snow off every once in a while instead.

If its not snowing, generally solar panels perform better in the winter than in summer because the heat during summer decreases their efficiency significantly.

drfish
Guest
drfish

Apparently, [url=https://www.blizzardsolar.com/autonomous-winter-solar-panel<]it's a thing[/url<], but it's not [i<]much[/i<] of a thing. I suspect it's a lot like the case for sending robots to Mars that can clean off dust of their solar panels, great armchair engineering fodder but deemed impractical by the experts.

sweatshopking
Guest
sweatshopking

Fantastic piece. I will be investing in one once wife and i are done these current degrees! i was interested, but didn’t know a ton about it. Your excellent use of numbers makes me far more interested. God willing, we’ll be in the tropics, so our production should be strong! I’ll send you some data when i get mine 😉

dragontamer5788
Guest
dragontamer5788

Great article! I like all the data you’ve posted.

I know that buying the battery-backup system is probably one of the bigger costs of your system, but yeah, you’re paying for peace of mind mostly. Thanks for sharing all of the big data.

Kevin Sweeney
Member

If I could sell kwh back to the grid at full price I might consider the investment, even in Indiana with iffy solar. But, that’s simply not practical and the grid isn’t really built for it, so the full price selling back to the grid seems like an unfeasible solution for now. I did get a simple 100W kit for toying around recently. Will take on a camping trip in a few months to provide 5V power with a tiny lithium motorcycle/ATV battery, but that’s about all it can really do. We have no big subsidies or legislation here to… Read more »

sweatshopking
Guest
sweatshopking

well, if you factor in the subsidies to fossil fuels it’s less one sided. without those subsidies the cost of ICE drastically increases.

drfish
Guest
drfish

FWIW, yeah, I went a bit overboard, lifelong dream and all that. However, solar can be totally doable at or near the “trade your electric bill for a loan payment” rate if that’s how you want to go. Also, the [url=https://news.energysage.com/congress-extends-the-solar-tax-credit/<]tax credit is from the feds[/url<], so it applies to you too. It's at least worth running the numbers IMO. That said, I don't know anything about the laws in other states or how other power companies offer credits. We recently got the PMI removed from our mortgage, due to the house value going up. Freeing up that extra $85/mo makes the solar loan a net $115/mo increase compared to our average 2017 electric bill or $40/mo compared to 2018's. As the price tag for a long term investment, it's not too bad.

dragontamer5788
Guest
dragontamer5788

Is there any chance you can give a more detailed cost breakdown?

For those who are interested in a cheaper solar project without batteries, for example. You’ve got an extremely decked-out, large solar project… lots of nifty bells-and-whistles. Far larger than anything I would consider for myself and more feature complete than most installations I’ve heard of.

Its pretty extreme, and cool 🙂 The typical installation I hear about is just solar panels + net-metering (no batteries involved). IIRC, just the solar panels + inverter.

drfish
Guest
drfish

The battery, and the infrastructure to support it added $10k. Since I bought it as part of the overall project I still get to claim the 30% credit for the added cost, though. Other than that, the costs scale pretty linearly from what I can tell. If you wanted a 10 kW system w/o a battery it would probably cost ~$27.5k and qualify for a $8.25k credit, leaving you at less than $20k for what would still be a very potent system. Do that with a 15-year loan and it’d probably be less than your electric bill if the usage… Read more »

JustAnEngineer
Guest
JustAnEngineer

It’s a lot less expensive than a pickup truck.

[url<]https://www.chevrolet.com/electric/bolt-ev-electric-car/build-and-price/trim[/url<]

blastdoor
Guest
blastdoor

If your concern about the subsidy is an income equality issue, then I do not think you need to be concerned. This subsidy does not make wealthy people wealthier. Instead, it encourages wealthy people to spend their money on an investment with considerable positive externalities.

Even if you ignore the civilization-threatening effects of global warming, the benefits of reducing air pollution from burning fossil fuels are considerable. Stated differently, thanks to subsidies like this, the children of less well off people will have cleaner air to breathe.

Anonymous Coward
Guest
Anonymous Coward

I suppose it could be viewed as a case where the wealthy buyers of subsidized Teslas would have otherwise bought something else similarly expensive, but which burned fossil fuel instead. So the subsidy is a useful way of redirecting expenditures.

As far as solar cell installations, a $60k car is a luxury, a solar installation that size is a home improvement, I say. A home owner does not IMO need to be particularly well off to add $60k onto the mortage.

dragontamer5788
Guest
dragontamer5788

[quote<]Even if you ignore the civilization-threatening effects of global warming, the benefits of reducing air pollution from burning fossil fuels are considerable.[/quote<] Everyone should want their neighbors to have solar panels: one of the major uses of electricity is air-conditioning, which just so happens to (usually) kick in on sunny days (more sun == more heat, which means more air conditioning). The fact of the matter is: solar panels mostly follow air-conditioner use patterns. So loading up neighborhoods with solar panels helps to stabilize the grid. The exception is the 6pm to 9pm timeframe, where the sun sets but the day is still hot. Night doesn't bring coolness until maybe 10pm or so. Utilities still have to tackle the "6pm to 9pm" problem, but at least solar panels solve the 9am to 5pm timeframe with regards to overall neighborhood air-conditioner usage. ** Subject to local conditions: some states have so many people buying Solar that they are now at risk for overgeneration of power. But most states don't have enough solar installations yet.

Kevin Sweeney
Member

I agree renewables are important for ecological reasons.

I would question whether tax incentives for individuals is better than spending the tax money on utility scale solutions. From my understand, utility scale is ultimately more cost effective for taxpayers, and of course we all pay into that in some form or another, whether on our tax bill or our utility bill. Therefore, I would think from a public policy and legislative perspective subsidizing utility scale solar installations is a better idea.

IPL here in Indianapolis does have several installations.

chuckula
Guest
chuckula

Incidentally, if my calculations are correct that 9.8kWh battery, when fully charged, should be able to generate 1.21 jiggawats to a Delorean for about 0.0292 seconds.

I make no warranty as to what happens if the batteries were to discharge that fast.
You might want to invest in flux capacitors.

dragontamer5788
Guest
dragontamer5788

[quote<]You might want to invest in flux capacitors.[/quote<] I mean, all capacitors use flux to operate. So... it'd just be regular ol' capacitors, right?

derFunkenstein
Guest
derFunkenstein

Thanks for ruining my childhood.

Usacomp2k3
Guest
Usacomp2k3

Thanks drfish! Great read. Here in florida I’ve considered it, but I’m cheap and don’t know that I’m going to stay in my current house long enough.

chuckula
Guest
chuckula

Great follow-up article Colton!
[quote<]You can only claim the credit if your system is installed and operational before the end of the year, so get cracking if you're interested, because it will take a least a few months to get one in place.[/quote<] Then the Emperor and Lord Vader need to find ways to properly motivate their installers before the end of the year! Incidentally, many years ago I took advantage of a tax credit to have a geothermal HVAC system put into a house (I've since moved out). I don't know if it's still available.

Mentawl
Guest
Mentawl

Really interesting read! Thanks 🙂

I’d be curious if the panel installation itself wouldn’t actually help with cooling the house a little too – what with now having an air gap between the panels and the dark roofing, and air being an excellent insulator, it could be the roof won’t soak up as much heat anymore.

drfish
Guest
drfish

We have substantial attic insulation but I’m very curious about this myself. I just covered >75% of my roof with energy-absorbing “shade” – how does that factor in?

godforsaken
Guest
godforsaken

(exactly what I was coming to point out/ask) Is your insulation on the floor of your attic? or your ceiling? If it’s on the floor (or even if it’s on the ceiling really, but, that won’t show the difference as well), you can get an infrared temp gun to compare the area under the panels vs the the areas where there is no panels. (nor tangential shade from panels) How much you can ascertain from this info is, well, I imagine non existent, but, it sounds like you’d be like me and almost be excited for the first face meltingly… Read more »

drfish
Guest
drfish

It’s on my list to investigate. Insulation is on the floor of the attic. Good idea with the IR gun.

UberGerbil
Guest
UberGerbil

This is the most elaborate excuse to post drone videos I’ve seen in some time.

drfish
Guest
drfish

wesparednoexpense.gif

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