Help wiring solar panels

[TexasFishRoom]

I just recently bought a Growatt 48V SPF 3000TL LVM 3KW OFF GRID INVERTER and 12 Santan solar t series 250w panels. Was seeing if y’all could help me for best wring “series/parallel” what way you would recommend connecting the 12 panels together. Any help would be appreciated.

 

[rmaddy]

Post the full specs of the solar panels. And post the relevant PV specs of the all-in-one.

 

[MichaelK]

OK, can you reconfirm that these are the spec for YOUR inverter? Looking at the specifications, I see a 60V minimum, and a 115V practical limit, with a 145 winter weather limit. Is that the same unit?

Assuming that your 250W panels are ~30VDC and 8.3A, you need to wire them such that the minimum is higher than 60 and less than 115. So, that would be 3 panels in series to get ~90VDC. What are your winter lows like? In a really cold area four panels in series might exceed the cold weather limit of 145Voc, but around freezing, it might only be 135Voc. So the best option it seems would be 3S4P to stay within the voltage limit. Four only if you are in a warm weather area that never gets colder then just freezing.

Now, the amps. The data sheet says that the amp limit is 80A, so four parallel strings of ~8.3A would be ~33A. So, that's within the amp limit.

One last thing. Because you have three or more parallel strings of current coming into the machine, they should be protected by fusing, or breakers in a combiner box. I like/use Midnight's 6 breaker combiner. Get 12A DC breakers for each of the four parallel strings.

 

[TexasFishRoom]

 

[rmaddy]

250W panels with a Voc of 37.6V. You have 12 panels.

The charge controller can handle 4500W of panels, an operating voltage of 60V-115V, a max input voltage of 145V and a charge current of 80A.

With that you have 3000W of panels so you are well within spec there. 3000W / 48V = 62.5A so you are well within the charge current spec.

You can put up to 3 panels in series to avoid going over the 145V max. With 3 in series you would put 4 in parallel. So your best arrangement would be 3S4P. That's 4 parallel strings of 3 panels in series. With 4 strings in parallel you need a combiner box since the resulting current will be over the 30A supported by MC4 connectors. Each string should be fused in the combiner box. The wire from the combiner box to the charge controller needs to be appropriate to handle about 33A at 145V for the distance you have.

 

[TexasFishRoom]

250W panels with a Voc of 37.6V. You have 12 panels.

The charge controller can handle 4500W of panels, an operating voltage of 60V-115V, a max input voltage of 145V and a charge current of 80A.

With that you have 3000W of panels so you are well within spec there. 3000W / 48V = 62.5A so you are well within the charge current spec.

You can put up to 3 panels in series to avoid going over the 145V max. With 3 in series you would put 4 in parallel. So your best arrangement would be 3S4P. That's 4 parallel strings of 3 panels in series. With 4 strings in parallel you need a combiner box since the resulting current will be over the 30A supported by MC4 connectors. Each string should be fused in the combiner box. The wire from the combiner box to the charge controller needs to be appropriate to handle about 33A at 145V for the distance you have.

Thanks for the help.

 

[TexasFishRoom]

250W panels with a Voc of 37.6V. You have 12 panels.

The charge controller can handle 4500W of panels, an operating voltage of 60V-115V, a max input voltage of 145V and a charge current of 80A.

With that you have 3000W of panels so you are well within spec there. 3000W / 48V = 62.5A so you are well within the charge current spec.

You can put up to 3 panels in series to avoid going over the 145V max. With 3 in series you would put 4 in parallel. So your best arrangement would be 3S4P. That's 4 parallel strings of 3 panels in series. With 4 strings in parallel you need a combiner box since the resulting current will be over the 30A supported by MC4 connectors. Each string should be fused in the combiner box. The wire from the combiner box to the charge controller needs to be appropriate to handle about 33A at 145V for the distance you have.

This is combiner box i have been looking at. https://watts247.com/product/solar-panel-combiner-box-4-circuits-to-1/

 

[Abodyofscience]

And if you have a 250w, 3.7 ohm resistor & full sun, you can check a panel before install.

 

[Rednecktek]

There are cheaper options out there if you need. FWIW

 

[MichaelK]

Midnight's combiner is cheaper and has higher capacity. That's what I use. BTW, that's the list price. Got one off Ebay for 63$.