red31 wrote:
BFL13 wrote:
I keep reading how you do better with the higher voltage in series unless there is shading.
stop reading!
yup, it's one of those "it depends" situations. first look at the efficiency curves on the controller, since it's likely a MPPT controller, ones I've seen have a varying efficiency as the panel voltage deviates from battery voltage. On mine max efficiency is when panel and battery voltage are a near match . When they are far apart there is a noticeable decrease in efficiency, more than one would often get from lower cable IR losses from series.
and then the panels need to be matched for best series performance as well. mixing panels can make series worse than parallel. Usually the max current will be limited by the lowest panels current. In parallel, each panels current adds to the total. But then mismatched panels with different Vmp can effect overall efficiency as well.
My experience is that when I have 150Ft portable runs with #10 wire AND 480W of panels AND well discharged batteries, AND no shading, AND bright sun series wins noticeably. Otherwise parallel is less hassle with shade and neither has enough benefit to dominate decisions, but parallel seems to be more forgiving.
