Panel Recommendations for Bluetti AC300/B300s for Off-grid detached garage.


New Member
Mar 31, 2022
Hi, new guy to this and seeking advice please. I have a Bluetti AC300 with 2-B300 batteries (6kwh) and will likely expand that to 12KWH of storage. the system will be stored in my 2-car detached garage at home. My primary objective is off-grid battery backup and powering the garage tools, etc. In a power outage, i have the ability to run a transfer cable from the Bluetti to my house panel to power fundamental appliances.

I'm looking to add rigid panels to the garage roof, which faces east/west but has completely unobstructed views. I'm looking for a simple system to install as this is my first solar project. Presently, I'm looking at Newpowa 210w 24 volt mono panels, a total of 10 - with 5 on each side of the roof.

The AC300 can handle 2 x 1200 W, each up to 150 V and 12 A. by my math, that would put each side watts at 1050 and max volts at 120 - well under the limits - for a combined max total of 2100w. My plan would be to wire each side in series and then both in parallel.

Im sure this setup could be expandable if i wanted to add a second AC300 for max solar input up to 4800. but for now, my questions are:
1) is there a general rule of thumb for panel amount/max input for the system being used?
2) my roof is asphalt shingle: are rail systems absolutely required? or can the panels be mounted just by panel brackets
3) do the panels needed to be grounded to an in-ground rod?
4) cable management: is the idea to cut a small hole in the roof for a junction box to route the wires going from roof to Bluetti? i have a loft in the garage so that's not a problem.
5) any other wiring suggestions to compensate for the east/west limitation of my roof?

all comments welcomed and appreciated. thanks