Different panels,different manufacturer

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claychps
claychps Registered Users Posts: 9 ✭
in Solar Beginners Corner #1
Hi all,
My question regards using different 12V panels with others. I have the 45w Harbor Freight set up and was given two Sharp 75w panels. Can I put them all together and if so, should I use an MPPT controller or will a Morningstar 20 be OK?
I just have a small system set up, (4) 6v 105A golf cart batteries, 400w dc-ac inverter with an extension cord to fish tank and another cord for Malibu lights. Working my way up as funds allow. My solar shed is in process.

Thanks for your time,
Robert
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
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    Re: Different panels,different manufacturer

    that was a good stroke of luck for you to get those pvs. if the harbor freight pvs don't have too low of a vmp then just parallel them all.
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  • claychps
    claychps Registered Users Posts: 9 ✭
    #3
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    Re: Different panels,different manufacturer

    Thanks Niel,
    Yes, sometimes it pays to let people know you are into solar. I also got a 165w 20A solar concentrator that is about 10 feet long. Haven't figured out where to mount that beast yet...lol.

    Robert
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
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    Re: Different panels,different manufacturer

    If you are going to wire them in parallel, the Vmp of all the panels should be similar,,, not vary by more than say 1/2 volt. The controller doesn't really care,,, but Mppt will give you a bigger harvest.

    Just so you know,,, you are way under paneled with that much battery. We recommend At least 5% of battery capacity in panel capacity. Your 4 t-105s would be about 500ah 12 vdc,, requiring ~15-20 amps minimum to charge efficiently. Your ~190 watts might yield a max of ~15 on perfect day

    Tony
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  • claychps
    claychps Registered Users Posts: 9 ✭
    #5
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    Re: Different panels,different manufacturer

    Thanks Tony,
    HF panels do not have great specs, 14.5v (working). Guess this is China's version of Vmp. I'll use them for something else. Looks like my (2) 75w Siemens (not Sharp like I stated), with 4.8a Isc x 2 will not charge just two of my t-105's efficiently. I'm in the So. Cal. desert which with summer coming on, will lower my output even more. Time to get a Tri-Metric and start logging data.

    Robert
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
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    Re: Different panels,different manufacturer

    The Siemens 75s will charge the T-105s,, but they will have a hard time keeping up with any loads. The 150 watts of panel might come up with ~10 amps on a good day, say 40 ah/day.

    If you use more than ~30ah/day you will begin to get behind. One option is to use a generator in the morning to bulk charge for an hour or two,, and then use the 150 watts to pump in the absorb charge. A honda eu-1000 driving a Xantrex TC 20 would put ~40 ah into the batteries in 2 hours using about 1 cup of fuel. Then the panels could pump in another say 30 ah,, so that you could use ~50-60 ahd/day to stay even.

    Tony
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