Joytech 5pcs 0.16w 4v 40mA Mini Solar Panel Module DIY Polysilicon Solar Epoxy Cell Charger B004

Although initially skeptical that reasonably priced solar cells could possess the quality I needed, I was unable to locate other round cells, so I placed the order. Upon arrival, I set up my digital multimeter, to check each cell for output. It was a bright overcast day, rather than sun, so I expected slight reduction in voltage per cell. To my surprise 90% of the cells tested produced more than 4 volts, with only 1 of 10 producing less than 4 volts.Actual voltages were: 4.04v, 4.12v, 4.20v, 4.06v, 4.10v, 4.18v, 4.12v, 4.05v, 4.17v, 3.90vI also tested two more expensive solar cells at the same time. http://www.amazon.com/Small-Solar-Panel-3-0V-70mA/dp/B00JMDG1AE?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00These cells were rated similarly, 3v 70ma (.21w). Of the two, one cell was inconsistent in voltage to the point of being unusable. The remaining cell fluctuated back and forth between 3v and 2.5v, even though light was constant. In comparison, voltage output of the round solar cells, was superbly consistent and steady,with no fluctuation of the digital meter display. For this, and the other reasons stated, I would not hesitate to recommend these reasonably priced round solar cells.I Hope this company will also make a slightly smaller square solar cell to provide options for other projects.

I measured 1.8 mA @ 3.4 V under 60 watt table lamp. Not a lot of current but good for solar engines that move a little every once in a while.

wired them together, got a zero output, BUT i may have done something wrong. i just dunno and got tired of messing with em. they may actually be OK. check other reviews.

Arrived well before due time. Tested a few straight out of the box, all work as promised. I am very pleased with my purchase, made my upgrade project very easy and fun. I may be buying more soon!

Useless

the units worked as described in the ad I'm happy with the quality as well as the speed in which I got the items I use them to power RC drones by sunlight so I add extra flying time to the unit

These solar panels absolutely exceed my expectations! It is nice that they provide copper solder tabs for the output connections. The output voltage in slightly overcast sky was still 4 volts.

The best thing about these is that they fit perfectly on a wide mouth mason jar. See image. Not modification needed.