460 watt solar setup: wire sizes?
I want to change out my old 50 watt panel and 10 amp controller with at least one and hopefully two 230 watt 24 volt panels and whatever controller would be best. Right now the roof on my fifth wheel ...
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Almot wrote:
12thgenusa - hitting 30A post-controller with 360W panel is extraordinary. Max panel output is normally no more than +/- 3% from nominal, if there is any QC at the factory.
360W @12.6V = 29.5A max at standard conditions (70F? don't remember), even if you got +3% more power than you paid for, zero loses in cables and 100% controller efficiency. In other words - unless battery voltage is less than 12V, this can not happen. Maybe it was some "sleep mode" or other effects? Was it unusually cold or at high elevation?
PS: correction, it's minimum 13.6V (or whatever your setpoint is). I don't see how you could get more than 25A current with 360W.
Several things. It's two 185-watt panels for 370 watts, not that that matters much. Elevation is usually above 8000 ft. Generally cool temps in Colorado mountains (60-75F). Panels tilted for optimum output.
From the data log on the Rogue I have seen over 400 watts more than a few times. The highest that I remember was 411 watts. Since the 411 watts is measured at the controller I assume wire loss is already accounted for. If you assume a controller efficiency of 96% the maximum voltage to reach 30 amps is 13.2v (411*.96/30=13.15). I quite often will operate a high demand appliance during the day; MW, coffee maker, hair dryer so voltage will drop well below 13v.
If one limits the use of solar to battery charging only, it is a different story. By mid-day when panels are at max, battery voltage has risen to the point that 30 amps is no longer possible.
For the OP at 460 watts a voltage of 14.6 or less will hit the 30-amp max. (460*.96/30=14.56)
