Solar conundrums

Ceci
Ceci Registered Users Posts: 2
in Solar Beginners Corner #1
I am interested in using solar power to run a house and am thinking of setting up a solar power system at my parent's home. My friend is also installing a set up at his house, I went to see how they do it. They have four solar panels and they met this problem where when the two panels are wired for 24 volt series there is an output of power however when the two series of 24 volts is wired in parallel for a 48 volt system there is zero output. I don't think they've solved the problem, at the moment. I am not an engineer and has a very basic understanding about electricity, but I'd really like to understand what went wrong and what should be done because my Dad is keen on using solar power at home, so I need to educate myself about it. Thanks to anyone who can help!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Solar conundrums

    Welcome to the forum Ceci.

    First lesson: solar is expensive. Almost always more expensive than grid power. Don't be thinking this is going to save any money, because it won't. A grid-tie system may, depending on the utility you're connecting to and what their rates/policies are.

    Second lesson: terminology is important. A series connection contains at least one positive to negative junction. As in you wire two 6 Volt batteries in series (-)BATT(+)---(-)BATT(+) to get 12 Volts, or four in series to get 24 Volts. A parallel connection is always negative to negative and positive to positive. The former adds up Voltage but not current, the latter adds up current but not Voltage.

    So if you wire two 12 Volt panels in series you get 24 Volts. But you then said "when the two series of 24 volts is wired in parallel for a 48 volt system there is zero output." Well, you wouldn't wire them in parallel to get 48 Volts; you'd wire the two 24 Volt strings in series to get 48 Volts. You may have meant that, which brings up the other possibility that the second string @ 24 Volts is wired in reverse to the first set: (-)PANELS(+)---(+)PANELS(-) then you get nothing.

    A good Digital Multi Meter (DMM) is essential to diagnosing the basics; keeping polarity and Voltages correct is half the battle.
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  • Ceci
    Ceci Registered Users Posts: 2
    #3
    Re: Solar conundrums

    Thanks for the reply. When I called up my friend his system was already working and what you stated in your reply was essentially what went wrong. I am understanding it better now.

    In my country, especially in my province what is getting a lot of households setting up or thinking of setting up solar power systems is not only the very expensive grid power but also the inefficient and problematic power service. First on the long list of complaints is that brownouts are so constant. We've got so much sun here, what better way to make use of it. :cool:
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