Off the wall question? Solar Panels

Zakarume
Zakarume Solar Expert Posts: 143 ✭✭
in Solar Beginners Corner #1
This might be off the wall, might be kinda wierd

If lets say i get theses http://www.renogy-store.com/240W-Poly-p/rng-240p.htm 3 x 240 = 720 watts at 24v
and http://www.renogy-store.com/100W-Mono-p/rng-100d.htm 2 in series for 24v at 200 watts

Total system at 24v @ 920 watts

Will a Midnite Kid MPPT handle this?
1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Off the wall question? Solar Panels

    Will a Kid handle 920 Watts on 24 Volts? Yes.
    Will you have 920 Watts on 24 Volts. No. The Vmp of two of the 100 Watt panels in series is 37.8 whereas the Vmp of the 240 Watt "24 Volt" panels is 29.8 - that's a 26% difference. What is likely to happen is that the controller will pick some optimum power point which will be the best it can do with the weighted compromise, but will not be as much as the panels on independent controllers. What is more, the Vmp of the 240's is too low for proper charging of a 24 Volt system. So they will contribute to Bulk but once the Voltage gets up near (or even over) their Vmp their current contribution will drop off.

    Will it work? Yes. But it sure won't be optimum performance or the expected output of the combined panel Wattage.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Off the wall question? Solar Panels

    BTW four of those 240 Watt panels in a 2x2 array will work fine: Vmp of 59.6, 960 Watt array should produce about 30 Amps on a 24 Volt system.
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  • Zakarume
    Zakarume Solar Expert Posts: 143 ✭✭
    #4
    Re: Off the wall question? Solar Panels

    but wont a 2 x 2 array make that a 48v system
    1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
    Re: Off the wall question? Solar Panels
    Zakarume wrote: »
    but wont a 2 x 2 array make that a 48v system

    Ah, but that's the beauty of a MPPT controller such as the Kid! It takes the excess incoming voltage and turns it into extra charging amps!
    Good example is my cousins cottage deep in the forest. He had to place his panels over 200 feet away where there was a clearing. Wired them in series to raise voltage and thus reduce transmission losses. Voltage coming in to his MPPT controller: 72. The MPT controller, as per it's design, then operates as a DC transformer, down converting the voltage to match his 12 volt system, and using all that excess incoming voltage to greatly boost the charging amps. All done automatically and at the Max Power Point.
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