Over-Paneling an MPPT Controller?

KE5YDKE5YD Solar Expert Posts: 32 ✭✭
When over-paneled, does the controller "output" at it's rated Max continuously OR does It do the Trip-Reset..Trip-Reset routine?

Specific controller of interest is the Morningstar 15a mppt; but I would like to know about others.

R. A.


  • VicVic Solar Expert Posts: 3,154 ✭✭✭✭
    Re: Over-Paneling an MPPT Controller?

    All of the MPPT CCs that I have seen, do limit current to protect themselves.

    It has been stated that the OB FM CCs may be a bit slow doing this limiting.

    AND, in general, it is wise to keep the amount of current beyond the maximum available from the CC within reason. Perhaps 15 - 20% above the maximum output of the CC MIGHT be OK ... it all depends upon the design of the CC. The MidNite Classic appears to be OK with a reasonable amount of extra PV power, above rated capacity.

    Would always ask the manufacturer of the specific CC for advice on this issue, however.

    Over-paneling can mean that when in Absorb, that Vin rises to a value approaching Voc, which can cause additional CC heating and efficiency reduction, unless you have a destination for much of that extra power. The added loading from opportunity water heating, A/Cing or even resistance heating will reduce the PV voltage into the CC to a more comfortable value, closer to Vmp. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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