I have a smallish solar panel (~60mm x 30mm) and I have decided to fly one on my next high altitude balloon launch (payload goes around 30km in altitude to near space) to log various readings to see exactly what power it generates above the clouds :D
However, I'm more of a software person than hardware so require a little bit of help please! My initial thoughts are to log Power from the solar panel by measuring pv across a "load" resistor. I will be using a 150ohm (or around about) resistor as the data sheet for the panel shows that peak power is obtained with a ~150ohm load.
The panel though will produce around 8 to 9v at ~45mA; so I require a pot divider to scale the voltage down to be used with one of the arduino analog pins.
My question is: does the resistor values of the potential divider matter and will they affect the power reading (Using P = (v^2)/R)? e.g. would there be a difference using 100ohm and 50ohm resistors to create pot divider or 100Kohm and 50Kohm resistors?
Any other hints/help would be greatly appreciated :)