BB. wrote: »
You can also use the Wiring Calculator in this thread to check your losses at various temperatures (typically, design for less than 3% total loss at worst case temperature).
The other place where you will have losses is the solar panels themselves. There Vmp output voltage falls with increasing temperature (the current rises a little bit with increasing temperature--but you can ignore the effect with little error).
My system (GT 3 kW) seems to vary from a cool spring day (60 degrees or so) to hot spring day (95F)--by about 5-10% output drop at higher temperatures (could also include the typically hazy sky we have in hot weather).
You can look up your panel's Vmp and temperature coefficient and plug the numbers into:
Note: I messed up the equation a bit--see following post for clarification (-Bill B.)
P=V*I=[Vmp @77F + Vtcf(77F-xxF ambient)] * Imp
I think that will work for you--I have to go.