After my research, I had a rough idea of what size system I needed to generate my annual power requirements. I also knew that, even though I'm not afraid of some DIY work, this was more project than I could handle without help. It was time to get some quotes and figure out if my plan was even remotely practical. I mentioned that there are lots of solar power calculators online, but there are also a number of services that will collect your details and share them with installers so they can produce bids for the job. I ended up using EnergySage for this step in the process and I highly recommend it. Answer a few questions, share a recent electric bill, and then sit back and wait.
After a week or so, I ended up with quotes from three different installers, all of them operating within about four hours of where I live. EnergySage's portal summarized the quotes and made them easy to compare. It also audited them to a degree, playing the role of a third-party fact checker. The portal provided a means of communication with the installers that didn't require me to share my direct contact info, which was welcome for the early stages of dialogue with them. All the quotes ended up in the same ballpark for cost and payback, but there were some differences. Each installer had their own preference for what brand of hardware to use and how much of it would be needed. The warranties differed too, both for the hardware and for the labor.
After engaging everyone in conversation for a couple weeks, I fleshed out the quotes by adding a critical load panel and requisite battery to them. I ultimately chose Strawberry Solar to do the job based on its combination of price, warranty, responsiveness, reviews, and its choice of hardware. I'll say this upfront: Strawberry was and continues to be a pleasure to work with. If you're interested in a solar project of your own, and they're a candidate to do the job, I highly recommend the company.
The process that lead to signing on the dotted line revealed one reason the quotes I got were so similar. It turned out that based on my electric usage, the system my household demanded was hitting the 20 kWp cap for residential solar power in Michigan. Even if that weren't the case, any effort to go higher than 20 kWp would result in a "Category 2" program where I couldn't get a credit for my power delivery rate, only for the supply rate. You can read details about that here, but it's specific to my power company and could vary elsewhere. At any rate, the 20.13 kWp system that Strawberry landed on was right in the middle of my own estimate of 18-23 kWp, which was fine by me.
As things worked out, the system Strawberry installed ended up being 20.46 kWp. That number is reached by multiplying the 62 panels on my roof by their rated peak performance of 330 W each. The original quote was for 61 panels, but Strawberry tossed in a freebie to make the array look nicer. As it turns out, the installers were just as excited about setting up a big honkin' system like mine as I was. I asked about the size of the system putting me over the limit for "Category 1" net metering, but I was assured that inefficiencies in switching DC to AC power meant that having slightly over 20 kWp in panels was not a problem. In fact, the two inverters in my basement only total up to 19 kW anyway.
Speaking of the inverters, let's dive into the specifics a bit. Fair warning: this won't be a technical deep dive. It's just to whet your appetite with an idea of what one of these systems looks like, and what, uh, powers it. A lot of new stuff got added next to the existing electrical panel in my basement. There's a new meter, a transformer, two inverters, a critical load panel, a box for breakers that allows both inverters to charge the battery, the battery itself, and a large raceway full of wires that connect everything together. We'll take a quick look at each piece.
The meter is an unassuming box with an important job: it tracks incoming and outgoing power from the grid. It's also responsible for making sure that power from the system doesn't feed back to the grid when there is an outage, ensuring the safety of folks working to restore power. The transformer handles switching the DC power from the battery into AC power that can be used by anything connected to the critical load panel during a power outage.
The critical load panel doesn't have any particular smarts; it's just full of normal breakers. However, in the event of a power outage, the items hooked up to it will continue to run, either directly from solar power coming from the inverters or from the big battery, by way of the transformer. Regardless of how much solar energy is being produced, only the critical load panel will have power during an outage. We've got our sump pump, furnace, refrigerator, a circuit that power's Ellie's room, and our cable modem and router hooked up to it. In the event of an outage, the basement will stay dry, the house will be warm, food's chilled, Ellie's humidified, and battery-powered devices online.
The battery itself is an LG Chem RESU, and it can store 9.8 kWh. Based on the loads it sees, that should be enough to last through most nights until the panels can take over and charge it up during the day. Hopefully, we don't have to deal with many outages that last that long, though. I can't stress enough how much peace of mind having the battery in the system gives me. Even if it was just for the sump pump alone, it would save me a ton of stress. In the worst-case scenario, it's a huge buffer between when the power goes out and when I need to fight with the generator.
We have the battery configured so that power is not typically drawn from it unless there is an outage. It could be configured in such a way as to minimize our power draw from the grid, but thanks to net metering, that isn't a big concern for me. Instead, I'd rather make sure the battery is always topped off and ready to go in the event of an outage. The controller maintains the battery by automatically cycling it to optimize its lifespan.