Double check MPPT 100/20 capacity

DIY
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1

I think this works, but I want to connect three PVs to one MPPT 100/20.

The specs on the cells are:
Power: 180W
Voc: 24V
Vmp: 18.9
Isc: 9.8 A
Imp: 9.5 A

Reading the datasheet on the MPPT 100/20, says 580W at nominal PV 24V.

So, my thinking is 180W * 3 = 540W at 24V. It should work.

Am I doing this math correctly? Am I reading the right lines? I don’t want to melt my MPPT.

Thanks!

I

2

What voltage battery are you charging, key missing info.

For a 12V battery max power is 14.5V x 20A = 290W.

For a 24V battery max power is 29.0V x 20A = 580W.

3

Oh, yes, sorry it is a 12V system.
I’m not using the LOAD terminals–I have the Battery terminals wired into my power system.

4

So as noted on that basis, the max output you can achieve is 290W, the table is for battery voltage.

Secondly, the max input current limit is 20A, so the max number of those panel in parallel is 2 as they are 9.5A x 2 = 19.0A, right close to the limit.

I suggest fitting 2 of those panels in series, 360W running at about 38V and 9.5A. It is OK to have around 30% extra power.

5

for a 12v system, connect all three panels in series. the 290w max power is the units output power max.
it will only be able to use 290w of the potential 580w connected, this way you will ensure that you have a longer duration of max power available to the battery during sunlight hours.

even tough you have 580w available from PV the controller can only request 20 amps to the batery and nothing more, even if you have 5000w available at the input the controller can only request 20 amps or 290w.

current does not flow or get pushed, current can only be demanded(requested) from a source to a load.

you have 580w on the roof, the 100/20 can only request 290w for battery charging the remainder of the watts potentially “stay on you roof inside of your panels”