road-runner wrote:
Try this calculator http://pvwatts.nrel.gov/
At my location it is pretty much dead on after 3 years of actual data. Being meant for grid tie systems, the default inverter efficiency is set to 96%. For a battery system I'd suggest changing that to 85% to account for charge controller and battery losses.
Yes, it is accurate, I've been using it many times.
They assume 1.1 DC/AC losses or 90% inverter efficiency, not 96%.
They also assume 100% controller efficiency.
Controller efficiency is typically 95% or better (at least, in MPPT).
Hence, harvested DC energy after controller and before the battery would be 1.05 times more than in AC column. I would just leave it as is and assume DC=AC.
I would not consider battery losses here. Some old battery will have ridiculous losses, and even a new flooded battery never stops simmering and heating your space, unlike AGM that simply stops accepting charge.
