100pcs 0.5V 400mA Micro Mini Solar Cell for Solar Panels 52mmx 19mm/2‘’x0.75” Polycrystalline Silicon Photovoltaic Solar Cells Sun Power for DIY Cell Phone Charger

As other reviews note, these are EXTREMELY fragile. That said, they do what they say on the tin (for the most part). Most of the ones I've tested end up reading in the 0.6v range under intense light, and have a consistent gradient of output as light is applied. They're trivially easy to get dirty - 90% or better isopropyl alcohol seems to do a good job for cleaning, and doesn't degrade the cells.

Cells are very small - 2 x 3/4 inches. The entire stack of 100 is an inch thick. Each cell is thinner than a postcard, line them up and you can feel the difference with your finger. The entire thing is about three stacked dominoes, the only things I could think of this small. They come extremely well packed. Lots of bubble wrap around a plastic-wrapped bundle of the cells. Still, delicacy is required in handling them. This is an incredibly thin glass substrate. I'm guessing a few will be broken in testing how to mount them to an adequate base material. They seem very powerful for their size. Under a very bright light the yield was 0.65 volts and 140 mA. The current surprised me. It will be interesting to see the results under sunlight. Getting 100 seems about right. There will be breakage at various steps because they are so delicate and I don't need all 100 for my projects. I like being able to make custom arrays of different voltage and current outputs and the price was awesome. Very pleased with the purchase.

Three stars because these panels actually work. I put six of them together and got 3.7 volts in sunlight. BUT ! There are quality control problems. I ordered one batch knowing I was going to give a bunch away. I had problems working with them as they are very fragile and difficult to solder. I ordered a second batch and the differenece is night and day. See photo. The soldering spots on the first batch were thin and often did not go one third of the way across the panel. There was great variation in the depth of the blue color as well. The second batch had good strong pads to solder to, all the way across the panel and on both sides. The blue was much more uniform as well.

BURN MARKS. these cells do work but they are straight up not meant to be used as components like this. Many of the cells have burn marks and other indications of quality being poor. But lemme not understate how incredibly fragile these things are. A name brand potato chip has more rigidity and flexibility than these things. They literally have the durability of a paint chip or dried snot, basically none. Any slight amount of bending force is likely to damage these. YOU HAVE BEEN WARNED.

About as robust as a potato chip. They can break if you breath hard on them. So plan on mounting on something firmer.

Arrived broken and unusable.

Order was quick and on time delivered. Quality is very good.

These are not solar panels, they are "cells", that make solar panels, and as cells, they are thin, very fragile and need to be assembled into your project, protected and in a way that gives you the voltage and amperage you need. Mine came to me without a single cell broken, and they all produce more than their rating, very much worth the money. Don't buy these if you think you're going to connect a couple of wires and make your robot run, understand the difference between a cell that is a part, and a panel that is a functional end product. That being said, I'm super happy with my purchase, I plan to purchase more.