Forum Discussion

MrWizard's avatar
MrWizard
Moderator
Jun 24, 2015

why don't Solar controller mfg/sellers use honest ratings

example most 30amp controllers are listed at 390w of panels and 40amp controllers at 500w of panels but we don't charge batteries at 12.0v we charge at 14v or higher 14v*30 amps 420w output, ...
BFL13's avatar
BFL13
Explorer II
Jun 26, 2015
The 30 amp controller can handle 30 amps. You need that ability when your panel can do 24 amps at STC so you can have the margin for when the panel does more than its ratings.

24 x 1.25 = 30 The panel and the controller are a "system" If you had enough panel to do 30 amps you would need a 30 x 1.25 = 37.5 so a 40 amp controller.

With PWM, you get panel Isc not Imp which has no meaning with PWM.

A 130w panel could have an Isc of 8.2 like my Sharp but some have more and some less Isc per watt at STC.

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