Off grid cabin build! Question about matching panels to expand.

MadmarcMadmarc Registered Users Posts: 14
Hi all! So about a month ago I purchased 4 new Solar tech (enphase) b grade panels off eBay for the system I'm putting together. I now would like to add 2 more but the seller has sold out. I've seen other 250 w panels with similar numbers but not identical. I'm looking to do 3 strings of 2 panels. The panels I already own have not been used.

What are my options? Do the other panels need to match perfectly? Will the system be hindered?

Thanks all! This forum is a treasure trove of info and I appreciate it.

Marc

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Off grid cabin build! Question about matching panels to expand.
    Madmarc wrote: »
    Hi all! So about a month ago I purchased 4 new Solar tech (enphase) b grade panels off eBay for the system I'm putting together. I now would like to add 2 more but the seller has sold out. I've seen other 250 w panels with similar numbers but not identical. I'm looking to do 3 strings of 2 panels. The panels I already own have not been used.

    What are my options? Do the other panels need to match perfectly? Will the system be hindered?

    Thanks all! This forum is a treasure trove of info and I appreciate it.

    Marc
    If you will be putting the new panels in series with old panels, the current specifications, Imp and Isc should be within about 5% between old and new panels.
    If you will be putting the new panels in parallel with old panels, the voltage specifications, Vmp and Voc, should be within about 5% between old and new panels.
    Matching the power output number is not as important as matching the voltage or current numbers depending on how you will be wiring them.

    I do assume that you are using a central string inverter. If you are using microinverters, then as long as the numbers are within the input specs of the inverters you do not need to match anything. For mounting, it would be nice if they are the same physical size.
    SMA SB 3000, old BP panels.
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