Does this sound ok?

castilloj
castilloj Solar Expert Posts: 208 ✭
in Off Grid Solar & Battery Systems #1
At one of our Campuses we have 13 small solar panels (SBM Solar Model AW49)
Connected to a MPPT 45. At 1pm I measure the panels and they were 68 v
Also the Inverter is a Mean Well tn-1500
There were 4 trojan T105 batteries powering 11 30 watt flouresent lights.

My question is would this be enough power to last thru the night without using a generator to charge the batteries?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Does this sound ok?

    The charging won't have any bearing on the batteries lasting through the dark. So lets see what happens when we multiply 11 * 30 and get 330 Watts. Now, how many hours are they actually on for? That * 330 give you the Watt hours.

    If we look at the battery capacity in Watt hours you get (225 / 2 * 6 Volts) 675 Watt hours each, and there's four of them so that's 2700 Watt hours at 50% DOD. The inverter will use some of that of course, but if you divide it by 330 you get approximately 8 hours of light time (expect a bit less).

    Now if those panels are 49 Watts each that's a total of 637 Watts. If you can expect 6 hours of equivalent good sun you'd get about 1987 AC Watt hours, which is enough for only 6 hours of light time (expect less).

    Again, it matter how long the lights are on and how much the inverter draws. I'd say it's marginal on the batteries (especially as you do not want to discharge them 50% every day; they won't last) and the panels are about right for those batteries (based on the Wattage assumption).
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Does this sound ok?

    Not enough information.

    All design criterion start with the loads. Define your loads carefully, and th battery bank size and PV and genny configuration become clear(er).

    How long are said lights going to be on for example? How ,any hours of. Good sun do you expect.

    Tony
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