SUNYIMA 5V 60mA Epoxy Polycrystalline Solar Panel Cells for Battery Charger DIY System Kits 68mmx37mm / 2.67"x1.45"

I was using these for a small project and in testing I had one faulty cell that would not output voltage to the specs. Not a big deal though. Also, many of the cells were curved like they were peeled up, which was kind of strange. I was using thin double sided tape and I couldn't get the edges down flush on the surface. Either way, great price and function over form, they worked well.

These devices are well made and deliver what they promise. Using a Fluke 87, in direct sunlight I was reading 6V from the cell, in regular sunlight I was reading 5.5V. In the shade I can read 4.4V, with a 6000K fluorescent photographers light 4.4 V and in an incandescent 40W light 2.5V. Note the amount current will vary with your load but I was able to directly pull 60.4 mA from the direct sun light.I bought these to replace a broken panel on a desk novelty that drives a motor (a metal object with a stick person riding a bike). This cell drives the motor better than the old cell.The epoxy coating is a great touch. The previous solar panel broken into pieces due to lack of coating. I dropped one several times on a solid wood floor (about 4.5 feet) and it did not break, crack or stop working.

I've used several dozen of these cells so far, and they've been largely trouble-free. Power in direct sun is close to the rating when pointed directly at the sun; in more practical horizontal mounting I'm getting about 50 mA (short circuit current) and mounted vertically about 35 mA around noon time at 34 degrees latitude. In full shade but with full sky exposure (e.g. pointed north, rather than south and getting only indirect light from the sky) I get about 3 mA.The get four stars instead of five due to two issues:The power leads from the cells to the PCB are located right on the edge of the cell (the power terminal part of the PCB is dead center.) As a result if you don't have a perfect weather seal at the edge you can get corrosion there which will eventually kill the cell.The epoxy also isn't particularly sun resistant, after a couple years in the harsh sun of Arizona, the surface has crazed, yellowed and oxidized, but is still intact and this has only lowered the power output by a small amount.

First off, these are not top of the line monocrystalline panels. If you're looking for a voltage regulation down to the 0.1V, these aren't the panels for you. But if you're looking for panels to tinker with, these work great!My tinkering teenager son used these panels to create an array that can charge portable power banks. Running them in parallel, he was able to get about 5V and 500mA. Enough to charge a power bank, small GPS, flashlight, or smartwatch, but not enough to charge a mobile phone or tablet.These also work great for tinkering with small motor projects, such as solar powered cars and fans. Just a little soldering skill and circuit math and your imagination is the limit!Only slight negative is that we had a voltage range of about .6V at the extremes. For 5V cheap panels, this is well within the tolerance of frugality!

I am not using these in full daylight, but rather in a bright room, measured 3500 lux for an art project. Expected performance for solar cells is that open circuit voltage Voc should be relatively independent of light intensity but short circuit current Isc should depend on light intensity.I measured voltage at different load resistances, and calculated current = voltage / resistance and power = voltage X current. Power maxes out at about 2.1 mW under a 4000 ohm load for a good cell ay 3500 lux.Voc under my conditions 3500 lux is about 4.2V, but Isc maxes out about 1mA. Connected in series one can increase voltage, and connected in parallel one can increase current, see graphs. Both increase power output. This is as expected.Quality control may not be great for these parts. I had one dud cell among ten where voltage dropped to almost nothing under small loads and power maxed out at about 10 microwatts.Be sure to test cells under a load of 3000 to 5000 ohms to be sure you do not have a dud. Note that open circuit voltage Voc is still about normal for a dud!

Hands down best solar panel out there! These are so user friendly and compatible with everything! I feel like I hit the lottery just finding such an incredible product for so cheap. This product exceeds its claims in voltage, ampacity and durability. Sunyima my new favorite panel supplier!!!!!!

The media could not be loaded. Perfect for DIY projects. I wire three cells in parallel. That gives me enough voltage and current to run my solar projects inside under indirect sunlight which is about 3 volts under load. I’ve used 16 of these solar cells and have no failures. Highly recommended.

I bought these to charge batteries that sit alongside a race track. The fastest run in 10 years hit them directly and destroyed everything but these tiny panels. A very good value and I've bought more since.