Oversizing Charge Controllers

[Bendesa1962]

Hi all,

I know that for grid tied inverters oversizing is a common thing to do. I was wondering what the thoughts on oversizing charge controllers are.

I have Two Outback FM80 Charge Controllers with an Outback inverter 3048. The battery bankruns on 48Volts.

The mac Amps for the FM 80 is 80Amps and MAC VOC is 150 VCD

I have panels of 550 Watt with the following specs:

MaxP 550 Watt
Voc 49.8 V
Isc 13.98 A
Vmp 41.95
IMP 13.12

Maximum recommended PV Array for the FM80 is 4000 Watt

My question is as follows:

Can I connect 3 x 3 panels in series connect in parallel with the FM80

Voc of each string will be 3 x 49.8 = 149.4 V (< dan 150 V)
Isc of each String will be 13.98
For 3 Strings the total Isc will be 41,94 A


The total Array will be 149.4 V (< 150 VDC) and 41,94 A (< 80 A)

So I stay within the limmits of the charge controller. But the Array is oversized. 3 x 550 Watt x3 = 4950 Watt

What do you guys think about this oversizing?

Many thanks for participating

Kind regards

Ben

[Bala]

I think if the manufacturer sets Max size then you risk damage if you go over. So check with manufacturer.

I have Bcdc chargers in my cars. They charge from car battery to auxiliary battery and have solar imput. The manufacturer states you can have any size array you want but the unit will limit amps to tge battery to its nominal size. I have 40a and 25a units.

[littleharbor2]

3 panel strings will not work in this case. The first cold sunny morning will cause your panels Voc to exceed the 150 volt max. You can go 2s4p and keep the extra panel for back up.

[jflorey2]

Can I connect 3 x 3 panels in series connect in parallel with the FM80

Voc of each string will be 3 x 49.8 = 149.4 V (< dan 150 V)

That is only true at 25C. As temperatures drop voltages will get higher.

So unless you live somewhere where it never gets below 25C, that won't work.

[Bendesa1962]

That is only true at 25C. As temperatures drop voltages will get higher.

So unless you live somewhere where it never gets below 25C, that won't work.

Thanks, you are right. That is something Imissed. Many Thanks!