SOL V2 Hello World

A project log for SOL: Long-term solar intensity sensing

SOL is a project to develop a solar powered, connected solar intensity sensor (also known as a pyranometer)

Jake WachlinJake Wachlin 10/02/2018 at 02:140 Comments

Working off some of the successes and failures of version 1, I recently designed and built a second version of SOL. There were a variety of goals here:

I will be adding the BoM, design files, and firmware for SOL V2 soon. For now, some pictures of the two assembled devices made so far:

I tested the power measurement sub-circuit, using 5 difference settings of the ADC PGAs (4.096V, 2.048V, 1.024V, 0.512V, and 0.256V full scale ranges.) With the amount of light available (indoor lamp in a mostly dark room), the ADC did not saturate at any PGA level, and the scaled measurements all matched nicely. One example is shown below. A fairly typical solar panel IV curve can be seen in the top subplot. Overall, the levels of measurement seems lower than expected, but I will need to see its performance in direct sunlight to check if it is ballpark correct. For reference, at maximum power this panel should be about 5.5V and 100mA. Note the power density subplot at the bottom is assuming a panel efficiency of 15%, and it just for reference.