Please check my setup

[Prefersdirt]

Please double check my math. I am at the point of getting the mounting supplies to put the panels on the roof. Want to maximize the number of panels. I have 10 panels – figured out I can put more up, but that is all I have. Information as of now is:

Each panel is:
250W,
37.6V max
8.27A

I have a Midnight Solar breaker box that will hold 6 DC breakers, so there is flexibility there.

I am currently using a GroWatt 3k at 24V for the inverter and PV controller. My intent is to use part of the next “stimulus” check to buy a tier 1 inverter and SCC.

The GroWatt has a PV max voltage of 145V with a range of 30~115V. Typical Amperage is 80A. I can’t find max Amps in the manual. On page 39 the max charging current is 140Amp (ouch!) If you know better info, please share.

What I currently am looking at is 3S3P. Each set of 3 would give me 750W, 38V, and 8.3 amps. Putting them into parallel gives me 2250W, 114V, and 25A.

I can’t go 3S4P as that overages my voltage at 152V.

I don’t think I can go 2S5P as that overages my voltage as well.

Is the 3S3P the max I can get with the equipment I have now? I think I have the ability to add another 4 panels (max of 14) to the roof space, but that requires another order. One step at at time. Get as many as possible operating.

Thank you

 

[Forbisher]

Your math is off. Try redoing the calcs.

Each panel is: I presume Santan panels?
250W,
37.6 V max? Voc??? Not Vmax!!
30 Vmp or Vmax
8.27A

3 in Series is 37.6V x 3 = 112.8V
Series adds volts only
Parallel adds amps only

3S 3P is 30Vmp x 3 = 90Vmp and 8.27A x 3 = 24.81A

9 250w panels is 2250watts at 24V battery is 93A for scc.

 

[Prefersdirt]

Here is a shot of the specs from a panel.
Thanks

 

[Forbisher]

View attachment 42183
Here is a shot of the specs from a panel.
Thanks

Yeah. I had the Voc and Vmp right for those Santan panels.

Do you understand how you got the 3 in series total voltage wrong?

 

[MisterSandals]

Do you understand how you got the 3 in series total voltage wrong?

I think he got that right (or close at 114v)

What I currently am looking at is 3S3P. Each set of 3 would give me 750W, 38V, and 8.3 amps. Putting them into parallel gives me 2250W, 114V, and 25A.

It was the 3S4P where he mis-calculated using 4 x Voc to 152v.

Recommendation on how to proceed for my would depend on whether your battery bank is 12v or 24v.

 

[Prefersdirt]

Do you understand how you got the 3 in series total voltage wrong?

Yep. I read the wrong line - used the correct one in my initial calculations.

Recommendation on how to proceed for my would depend on whether your battery bank is 12v or 24v.

24V (I will add this to the OP).

Thank you

 

[Forbisher]

Yep. I read the wrong line - used the correct one in my initial calculations.

Thank you

Also you use Vmp instead of Voc for production power.
3 in Series is 90Vmp not 114Voc
Voc is only used to size the scc for max volts input.
Vmp is also used to size the wire gauge along with Amps and distance.