Feedback and suggestions on 13 kw off grid system with sma sunny island

sashko559

New Member
Updated:
Feedback on off grid solar with transfer switch to power house loads

Hi, I am building an off grid system to charge a tesla and also an a second panel where I can switch off some load from the house (mainly AC or well pump or the whole house since there is outage often) to my system sometimes. I have 2 x sunny islands (5048) that will give me split fase 240V around 10 KW connected to 12 x 100 Ah Lead acid batteries 12v each in series 4 each to make a 48v power bank. I have used 40 panels that are 250W each that I bought as well as 16 panels that are 195W each. I can connect them through AC. Coupling.
I have 2 x 7.7 Sunny Boy's PV Inverters and theoretically I connect them on Load Panel with the Sunny Island which will allow me to use the solar power and the excess to charge the batteries. It will also give me freedom to add more panels, Sunny boys and or Sunny Islands later to expand if I need to as well as the ability to add a backup generator.
I am confused how to connect on the sub electric panel the sunny islands and sunny boys with other loads. Which breakers and which panel should I use? Also can you recommend any transfer switch panels I can put in the house and wire a load from this sub panel to switch some loads independently off and on from grid and solar system
Please Provide feedback and suggestions:
  • Type of wires to connect within the system the Inverters, panels, and the batteries.
  • Overall Design of the System and any improvements and changes.
  • What kind of panel and switches I would need to put that would allow me to transfer switch every load depending whether I want it on the grid or on the solar system?
Thank you very much for all the help so far!
Love this community and the videos!
 
Last edited:

Pyrofx

Flux capacitor builder
I use 2 of the sboy 7.7, and 2 s island 6048.
The islands will control the charging of the batteries, then the boys will ramp down the islands charge rate when full. The boys will also increase you ac load available.

The boys have 3 mppt inputs , and you can parallel the inputs.

Stand by , Hedge will chime in soon . He is an SMA slut . He is who talked me into my 5 sma units.
 

sashko559

New Member
I use 2 of the sboy 7.7, and 2 s island 6048.
The islands will control the charging of the batteries, then the boys will ramp down the islands charge rate when full. The boys will also increase you ac load available.

The boys have 3 mppt inputs , and you can parallel the inputs.

Stand by , Hedge will chime in soon . He is an SMA slut . He is who talked me into my 5 sma units.
Because I have different solar panels listed above, do you think the 3 strings on the sunny boy input have to have same voltage and panels each? Or can I do different amount on each string? Specifically I want to do 10 panels 250w in series on string 1. String 2 is identical. String 3 would be 8 panels 195w each. Also which 5 SMa units are you talking about?
 

sashko559

New Member
I use 2 of the sboy 7.7, and 2 s island 6048.
The islands will control the charging of the batteries, then the boys will ramp down the islands charge rate when full. The boys will also increase you ac load available.

The boys have 3 mppt inputs , and you can parallel the inputs.

Stand by , Hedge will chime in soon . He is an SMA slut . He is who talked me into my 5 sma units.
Can you share please a picture of your sub panel or critical loads panel? I a bit confused on which breakers to use for each inverter sunny boy and sunnn island on that sun panel if my sunny boys are 240v and 2 sunny islands are split phase 240
 
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