I have a couple of small solar panels gathering dust. They have an OC voltage of around 20V. I would like to use them to charge some NiCads, maybe 3 or 4 in series.
I have read about people using PWM and changing the duty cycle up or down, checking the current and voltage and iterating. Here's the dumb bit: Do I measure the instantaneous current and voltage, and havin knowledge of the duty cycle, calculate the mean power? Or is it more complicated (or possibly less complicated) than that. I'm not looking to squeeze the last microjoule out of the solar panel, but would like to use bits and piece I have on hand, e.g. ATTinyxx, FETs etc. I don't have inductors to hand.