Through another of my projects, I am acutely aware of just how little power is available in shady conditions, and how much less is available indoors. Therefore, even though I am planning to have two parallel solar cells, each rated at 5.5mA at 4.46V at their max power point, it is unlikely to harvest anywhere near that amount indoors. Therefore, I wanted to do some initial prototyping using artificial light.

Underneath a lamp with a high-intensity LED bulb, I was able to get somewhat close to the rated voltage and current. As can be seen in the below three images, it reached 4.59V open circuit voltage and 2.16mA short circuit current. This would more than enough to operate continuously at a slow clock rate, but the light is very intense.

Next, I tried testing with the lamp farther away from the solar cell under test, this time reaching 3.42 V open circuit voltage and 0.26mA short circuit current. Again, this may be enough to operate the board continuously, depending on microcontroller settings.

Finally, I tested with the normal amount of light in this admittedly dim room. It is light enough to easily see, and for the camera to take a decent picture, but the open circuit voltage drops to 0.3V, and short circuit current is about 1uA. The multimeter used isn't great, so those measurements aren't likely very accurate. Nonetheless, it shows that this board will need reasonably bright light.