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July 8, 2025 5:50 am
I am doing research for my setup. I have dual 200A panels from a 400A meter. I am planning on dual Gridboss one for each panel each with dual Flexboss21. Each panel would have 10KWh of Solar and it's own battery backup. Essentially, two separate units. I want to add a generator backup. I was planning on getting a single 48KWh Generac generator which outputs 200A that feeds to both Gridboss units... Is this possible? Or do I have to get 2 generators at 24KWh each? I was hoping to only have to get a single generator vs having to maintain / service 2 of them.
Am curious if both Gridboss units can control a single generator and tell it to turn on / off when the grid is down.
July 14, 2025 3:09 pm
I don't understand why you couldn't parallel the start relays to control the generator. Any gridboss calling for the generator to start then gets power from the generator, transfers load and starts charging the connected battery. The other one will just transfer the load, but not necessarily charge the batteries.
November 1, 2025 3:46 pm
I am doing research for my setup. I have dual 200A panels from a 400A meter. I am planning on dual Gridboss one for each panel each with dual Flexboss21. Each panel would have 10KWh of Solar and it's own battery backup. Essentially, two separate units. I want to add a generator backup. I was planning on getting a single 48KWh Generac generator which outputs 200A that feeds to both Gridboss units... Is this possible? Or do I have to get 2 generators at 24KWh each? I was hoping to only have to get a single generator vs having to maintain / service 2 of them.
Am curious if both Gridboss units can control a single generator and tell it to turn on / off when the grid is down.
Your panel and meter base setup sounds exactly like mine, 2-200 amp panels and 1-400 amp base. But, my house doesn’t require 400amps, not even close, I could have gotten away with 1-200 amp service but there’s way too many circuits for 1 panel so we were forced to go with this setup. If you can get away with using 1 of those 200amp feeds for your inverters/Grid-Boss it will give you a ton of options.
March 1, 2026 4:11 pm
I just installed a very similar architecture. I have a 400 amp split SE with two 200A breakers immediately after the meter, all combined in the SE panel. The load panels are two 200A panels. I just installed dual Gridbosses, dual Flexboss21's ( one feeding each GB) and four 314 Ah wallmount batteries (2 in parallel with each Flexboss). I just converted my 24kW Generac to 2-wire start which seems to be working fine from the Gridboss #1 included inwhat I will call system #1 (Gridboss/Flexboss/2 batteries). This serves most of my critical loads.
According to an EG4 document the Gridbosses/Flexbosses can be set up in a dual fashion sharing what appears to only be the RSD external switch for shutdown, the generator and the grid. It does show the generator output coming into both system #1 and system #2. My 2-wire control through the dry contact #1 NO1 and COM1 controls the generator to initiate starting. I have a splice in a junction box that then feeds to the generator port in each of the 2 Gridbosses.
My question is if I lose Grid and the generator conditions are met to introduce it to the system for load/charging is, what happens to the other Gridboss (system #2) when the GB #1 relay switches out the grid on system #1? The grid is still technically connected through system #2 (at the meter common) if Gridboss #2 does not initiate the relays to switch out grid / switch in generator. How does Gridboss #2 know to trip the relay?
The EG4 document is attached. (DRAWING #GB-V2-1L-1, VERSION 1.2 ©2024 EG4 ELECTRONICS, LLC. ALL RIGHTS RESERVED. )
