SUNYIMA 10pcs Mini Monocrystalline Solar Cells Solar System Kit 50mm X 50mm/1.96" X 1.96" 2V 160MA for DIY Charge Solar Panels

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Got these a few days ago and are as advertised, seem to be good little solar cells. Perfect for charging up 1.2V NiMh factoring in a 0.7V blocking diode, even better with a Schottky. Might buy some more.

These are easy to use in DIY projects, tested with a volt metre and they do provide as specified, they can even surpass the advertised specification in direct sunlight. Would buy again.

The panels are well made, sturdy, and look good. But they produce nowhere near the specified conversion efficiency. Today is a cloudy day and at 3000 lux illumination, one panel produces only 3mW of power (1.5V, 2mA). That calculates to only around 7% efficiency, not over 20% as the description says. Here's the calculation, if anybody is interested. I measured that the active area of the cell is 42x42 mm, which is 0.001764 m2. Full solar illumination is defined as 1000 W/m2 at 118000 lux. The power is proportional to illumination, i.e. at 3000 lux, full solar power is 1000W/m2 * 3000 lux / 118000 lux = 25.4W/m2. As the panel produces 3mW with 0.001764 m2 surface area, the efficiency is: 0.003W / (0.001764m2 * 25.4W/m2) = 6.7%

I tested several cells and allowing for the lab conditions element, 160ma turned out to be 8ma.