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bossrox avatar image
bossrox asked

Confusion on 150/100 current handling capability?

I was looking over the specs in the manual for my 150/100 & noticed it had a warning just below the max watt input vs voltage that says, max pv short circuit current, 70amps.

I might be misinterpreting something here but I'm currently feeding it 100 amps from 4 sets of 3 - 320 watt 40 volt panels in series or about 3800 watts @ 120v & according to the specs I can add even higher wattage but this 70 amp max doesn't make any sense if it's rated for 100 amps output.

Can anyone explain what I'm not getting here?

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2 Answers
Vance Mitchell avatar image
Vance Mitchell answered ·

If you have 3800w @ 120v going in to the controller then that is only 32A input. The controller then converts that to your battery voltage and higher Amps (up to the 100A limit). In your example the maximum Amps would be 4 x Isc (short circuit current times number of parallel strings).

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bossrox avatar image bossrox commented ·

Being a bit fuzzy on electric formulas, I automatically assumed because my combined panels in parallel would be 100 amps @ 40v & I get a full 100 amps when charging my batteries @ 24v, that I was inputting 100 amps but in a series combo like I have, it's as you say, about 32, the controller is adjusting the ratio so I was interpreting what i saw correctly & feel at ease now that I'm not even close to over taxing the controller. Thx for the feedback!

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lklmenterprises avatar image
lklmenterprises answered ·

The other important thing is the MPPT will handle Up to the 150v input - which CAN NOT be exceeded or it will burn out the MPPT pretty much straight away. You can however have higher input current capability - it just won't use any more than it's rating - that being the 70Amps.

It effectively can handle 150v x 70 = 10,500 watts - as Vance2loud said - you have 3800w which is about 31.66Amps.

To work out what you have though...

if the 320w panels are 40v - that means they are no more than 8amps each

so:

3 x 40v x 8a = 960w in series = 120v @ 8amps (amps remain the same in series)

4 x 8a x 120v = 3840w parallel total = 120v (voltage remains the same in parallel) @ 32 amps


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bossrox avatar image bossrox commented ·

Ahhhh.... That's where I got confused, I forgot about the same amp rule in series. Thx!

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