Matching solar panel output to charge controller

big402red
big402red Registered Users Posts: 7 ✭
in Solar Beginners Corner #1
Example: 700 wattes 7.5 amp 24v output.

So I would use a unit that can handle the minimum 700 watt /7.5 amp/24v

But can I go for a higher capasity unit if I plan to add on later?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: Matching solar panel output to charge controller

    A conventional PWM controller will only allow you to run the same (nominal) panel voltage as battery voltage
    An Mppt type controller will allow you to (typically) input higher panel voltage and output a lower battery voltage.

    For example a conventional controller you would wire with (nominal) 12 volt panels (~ 17 vdc) and input into 12 volt battery system, but a MPPT one could wire the panel volatage 12 or 24, or even higher depending on model) and the controller will then down convert to a battery voltage of 12 (or 24) or higher. It is a much more efficient controller type i general, especially in larger systems. Because you can run higher panel voltage you have smaller wire sizes and potentially less loss.

    As for buying a controller, buy the best one you can afford, relative to the size of your expected array, and assuming some head room to grow. Personally, in smaller (30 amp) I like Rogue 3024 which will take 30 amps into either 12 or 24 vdc. Mornins star also makes a couple of nice smaller MPPT controllers. In larger specs, Outback, Morningstar and Midnight solar.

    Under no circumstances consider buying a BZ brand controller.

    Good luck, welcome to the forum and keep in touch.

    Tony
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