Watts needed
I have read where folks suggest any where from 1 to 2 watts of solar per ah of battery. My question, is this based on battery rating (ie 215 AH) or is it based on useable amp hours(105)? All reply...
Forum Discussion
Those Victron terms don't mean anything to me, such as Pmax. Please use volts and amps and where you measured those.
The easiest measurement is output watts, where the controller will have a reading of battery voltage and the solar amps output (not to be confused with amps to the battery!!!) Multiply those to get your output watts.
Pick a number for your controller's efficiency--say 97% --then now you have your approx input watts. Compare that with your panel watts rating.
If you do that with the panel aimed at high sun your input watts should be less than panel rating by about 10% for panel heating and another 2% or whatever for wiring loss.
If panels flat, then you can get a rough idea of the loss there from your latitude and the day of the year.
The easiest measurement is output watts, where the controller will have a reading of battery voltage and the solar amps output (not to be confused with amps to the battery!!!) Multiply those to get your output watts.
Pick a number for your controller's efficiency--say 97% --then now you have your approx input watts. Compare that with your panel watts rating.
If you do that with the panel aimed at high sun your input watts should be less than panel rating by about 10% for panel heating and another 2% or whatever for wiring loss.
If panels flat, then you can get a rough idea of the loss there from your latitude and the day of the year.
