Disclaimer: The following was not sponsored by Harbor Freight. But it should be.
A couple weeks back we rehashed a recent story on PV panel fires in rooftop installations, and noted some industry standards that affect utility-scale panel design and installation. Today, we’re going down-market and playing with an off-the-shelf solar battery charging panel from everyone’s favorite purveyor of cheap import tools and related geegaws.
Now witness the charging power of this fully discounted
and imported solar panel!
This one seemed interesting enough for another video feature, so if you want to kill the next half-hour watching a panel actively tested in both conventional and non-conventional ways, and then disassembled to death, try our YouTube channel link:
For those who still think that video is the opiate of the masses, we’ve got a brief write-up below.
The box and product literature are sparse on technical specs beyond the listed 1.5 W output at 12 VDC nominal. Those who remember Ohm’s Law for power can calculate the nominal current at 0.125 A (125 mA). As renewable power output goes, this is roughly equivalent to firing a Super Soaker at a propeller beanie and calling it small-scale hydro. But the entire kit was around US$12 with the usual discount coupons, so it’s worth a look.
Things We Did included testing the panel on the bench, tearing it down to destruction, and then testing it outdoors in daylight. Unfortunately, we also did it in that order, and the second step was incompatible with the third, so another unit had to be purchased. That did give us opportunity to perform side-by-side physical measurements and calculations between glass only and the full assembly for the video feature, so it was money well spent. Or such are the tales we tell ourselves to justify bringing you this content.
We began our adventure with a brief bench examination. First impressions were good: it appeared to be some sort of solar panel. It also shipped with clip-type battery post connectors and a car socket adapter, swapped using a polarized plug. The actual panel glass measured just about 4 inches by 12 inches, or for those of you who like your measurement units to have a silly French accent, roughly 100mm by 305mm. With the frame, it spans roughly an additional inch in both directions.
Pretty much a 10:1 scale calculator solar panel.
Efficiency? None to speak of, assuming the advertised figures are both correct and based on the industry standard test irradiance of 1000 W/m^2. Here, a panel area of 100 x 305 mm is rated to produce 1.5 W. That output, divided by this panel’s area, divided again by one miiilllllion square millimeters, yields an estimated output of 50W/m^2. Fifty watts out for kilowatt in is just 5% conversion efficiency, which is better than, say, nothing, or a tax audit. But it also clocks well below the 15-22% that utility-scale panels are achieving these days.
The reason is the technology. Nothing on or in the package says what this is. However, the retailer’s website describes it as amorphous silicon thin-film, and that would be among the oldest and cheapest PV technology available. Purportedly, it’s the same design used in every solar calculator and solar-powered science project since the days when RadioShack was still a thing.
The raw cost per unit energy output also is not great, clocking around $8-10 for each Joule per second. Utility-scale panels are available in small orders right now from, say, Grainger Industrial, at roughly $2 per Watt. Then again, even a small industrial order requires committing to at least 1200 of those Watts (plus or minus a few) and arranging for a bill of lading, whereas this toy box-size wonder was available locally, off the shelf, for the price of a couple cups of Starbucks. And I can also use it to teach basic science to the rather bright progeny (you see what I did there) that inhabit house and home.
When one possesses a functional, but low-quality toy, what is the first thing to do with it? Around these parts, we group it with eight of its brethren and let them play together.
Just a little LED-meets-PV party trick.
We have here an eight-count of those free-with- any-purchase, COB-type, magnetic LED lights from Harbor Freight being used to power a solar panel from Harbor Freight. Or, stated another way, enough to represent every Chinese province in or around the SEZ, with a couple alternates in waiting should anyone’s party loyalty be called into question.
Amusingly, this trick generated around 15 VDC from the unloaded panel. Now we just need to connect the panel directly to the lights and we should be able to file that perpetual motion machine with USPTO next week. We also went a bit further down this rabbit hole, but you’ll need to watch our video feature for details.
The next step was to open the panel frame and see if the hardware could be removed from the shell. That enterprise went rapidly sideways, and other than verifying the plastic backer film was flammable and observing the glass applying 243g on the kitchen scales, we got no further. And we hadn’t done any of the outdoor tests yet.
Back to the store we went, and came home with a second representative of the species.