Solar Panels Brands - does it matter?
I am looking to buy 200-300 watts of solar panels to charge 200-240 ah of battery storage. Researching panels on the web, it seems that prices for solar panels have a very wide range. Putting aside ...
Forum Discussion
BFL13 wrote:
I don't think Vmp and Imp have any meaning wrt "12v" panels. The IV curve is for Isc and battery voltage. Voc in the 21s by rating. If those panels were in series with MPPT, then their Vmp might matter, don't know.
There used to be 32 cell panels which did not have enough voltage to charge 12v batteries to 14+v but the 36 cell panels do have enough.
Not taking into consideration the difference of cell voltage v/s temperature. I have measured many different panels under various temperature situations....
Example below shows the effects of temperature and how voltage decreases the hotter the panel gets. Yes the current almost remains constant but voltage does not. When you multiply the number of cells.... 36 X the voltage at different temperatures you realize that the panel voltages will vary almost 3 volts from 75 deg F to 140 deg F... I have measured many panels while "working" and the ambient temperature is in the 70-90 deg F range... I see over 140 deg F and that voltage drops like crazy....
3 volts difference on the panels make a big difference with PWM and MPPT.
