Efficiency advantage 12 vs 24v controller?

bmetbmet Solar Expert Posts: 630 ✭✭
I see that some controllers sold by this forum's host have option of either being 12 or 24v. Is there an efficiency advantage for 24v charge controllers when maintaining 12v battery bank?

I am confused by this statement concerning one of the Bluesky mppt controllers.

" The dual 15/20 amp rating will deliver up to 15 amps in 24 volt systems, or up to 20 amps in 12 volt systems. "

This sounds backwards to me. Shouldn't 24v be more electromotive force, pushing more current to the battery? Thank you.


  • BB.BB. Super Moderators, Administrators Posts: 30,737 admin
    Re: Efficiency advantage 12 vs 24v controller?

    I don't know about the Blue Sky controllers specifically--but most controllers have a output current limit of XX Amp at 12/24/48 volts...

    Being that power is equal to voltage * current, the same current will result in more power through the controller into the battery bank:
    • P=VI
    • 14.5 volts charging * 60 amp controller limit = 870 watts
    • 29 volts * 60 amps = 1,740 watts
    • 58 volts * 60 amps = 3,480 watts
    So, with higher voltage battery banks, the same controller can manage higher wattage solar arrays.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Sign In or Register to comment.