Hooking roof panels up to charge a battery bank?


New Member
I'm working with a contractor to plan out a large solar installation on my roof. They do all the electrical and tie it into the meter. I would like to use a large battery bank like a Bluetti AC200 type system in the case of a long power outage to charge from my panels (I looked into some of the videos on DIY banks or home battery systems and really just don't have the time, though they look like fun projects).

The panels in the plan right now are SIL-380 BK, which are 380W outputs obviously. What's the simplest way to use them in a long-term outage to charge a battery bank like the Bluetti AC200? I know it's max input is 700W so in theory I could only hook up two panels. Is there a simple thing I could ask the solar installer to setup to make this possible (I've heard some people refer to this as an emergency switch)? If this is not plausible what is the safe way to wire these large rooftop panels in a way that they could be used both regularly and for emergency battery charging?



Solar Addict
What inverter is being used in this system?
How many panels and how are they to be interconnected?

The open circuit voltage of AC200P is between 35V-150V, panel Voc=Open circuit voltage: 45.13V. So 1,2,or 3 panels in series seem appropriate.


New Member
My apologies If I am hijacking the thread, , but I have already kind of gone this route and perhaps jumped the gun.

I have an SMA Sunny Boy 7.7 inverter and 10.3kw of panels (REC Alpha 370 black x 28). The inverter has the Secure Power Supply (SPS) which provides a max 2000 watts to two 20amp outlet while the sun is shinning.

I purchased the Bluetti 2 x AC300, 2 x B300, and Fusion Box for split phase.

This will be hooked up to a 10 circuit transfer switch/panel (Reliance 310CRK), with the Bluetti fusion box hooked to the transfer switch via a standard 30A generator inlet box.

Here's where I think I may have jumped the gun. When the Bluetti split phase mode is used, hooking up 2 x AC300, 2 x B300, and Fusion Box the batteries must be charged via a L14-30 outlet. This is fine when the grid is up, but not when the grid is down.

The SMA inverter's secure power supply outlets are standard NEMA 5-15. I was going to use these two outlets to charge the Bluetti when the grid goes down, but according to Bluetti this is a no no when using split phase mode. I want the split phase mode because it increases the AC300 output from 3000 watts to 6000 watts.

Now I am needing to find a way to charge the batteries if the grid is out for an extended period. I can temporarily disable split phase mode easily enough to charge the batteries from the secure power supply of the inverter, but then that limits me to 3000 watt output while the grid is down.

I suppose I can limit my usage while charging and disable split phase mode, but I'm sure there must be another way.

Any suggestions?


New Member
Inverter: Enphase Energy Inc. IQ 7+ (240V)
Panels: 15x Silfab Solar SIL-380 BK

Not sure on interconnection. I'm thinking is it a simple thing to go in post install and disconnect 2-3 panels and plug them into some sort of splitters that I can then connect to a cable which I run down the side of the house, or do something similar right before it connects to the breaker box?

Here is the response from the installer when I asked about this-
"With regard to the battery, the Enphase microinverters are strung together in series and grid-tied. They cannot simply charge a standalone consumer battery (like a consumer battery bank or off-the-shelf product). Those panels go through a separate charge controller and it would be difficult and costly to physically separate the two installations."

Thanks @mopat
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