EG4 Inverters Split Phase with Grid Tie

[Wlester]

Hi, I am building a system with two EG4 6500EX inverters with EG4 server rack batteries just as shown in one of your recent videos. However, I am tying to the grid also. I only have 1 cable coming in from the grid and am wondering how you would recommend splitting this so that each inverter has a grid power in connection. Please let me know what your recommendation is.

 

[Samsonite801]

Hi, I am building a system with two EG4 6500EX inverters with EG4 server rack batteries just as shown in one of your recent videos. However, I am tying to the grid also. I only have 1 cable coming in from the grid and am wondering how you would recommend splitting this so that each inverter has a grid power in connection. Please let me know what your recommendation is.

Grid L1 goes to Inverter 1 Hot input. Grid L2 goes to Inverter 2 Hot input. Neutral goes to both inverter N inputs. Ground goes to both inverter grounding screws.

So what does your incoming '1 cable' consist of? Is it 240v with an L1, L2, N, and ground? Or is it a single 120v leg with a Hot (either L1 or L2), with and N, and a ground? You need to have a 240v incoming lead (to use both inverter inputs), or else if you only have a 120v lead, then you can only hook up a single inverter's input.

Also remember that the neutral main feed (before it splits) works for both inverters so it needs to be sized large enough to handle the 120v returns for both inverters. I think EG4 specifies about a 60a 2-pole circuit breaker with 4 awg cable (going off memory here, it's in the manual)...

You may want to review the manual as well before you hook anything up.

Ref:

https://signaturesolar.com/content/documents/EG4/6500ex/EG4_6.5_manual_revision2.pdf

 

[Wlester]

Thanks for the response! I do have an L1, L2, Neutral and a Ground in the existing grid tie cable. This currently feeds two 100 Amp Breakers though so I'm not sure I can get away with using a 60 Amp circuit breaker. I see in the manual that it specifies 4 AWG cable, but I don't see where it specifies a 60 Amp breaker. I was planning on re-using the existing 100 Amp breaker.

 

[Samsonite801]

Thanks for the response! I do have an L1, L2, Neutral and a Ground in the existing grid tie cable. This currently feeds two 100 Amp Breakers though so I'm not sure I can get away with using a 60 Amp circuit breaker. I see in the manual that it specifies 4 AWG cable, but I don't see where it specifies a 60 Amp breaker. I was planning on re-using the existing 100 Amp breaker.

Yeah the 100a breaker is sized to protect the cable, so as long as the cable is large enough to handle the 100a breaker it is fine. The EG4 shouldn't need that much (unless maybe in inverter bypass, charging low battery and with excessive house loads running off it, depending on your house loads).

The challenge might be whether that cable has too large of diameter conductors to be able to fit into the input connection lugs on the inverter. I think that's why EG4 says 4 AWG because that is the largest size which may be able to fit into the lug.

4 AWG equates to 85a max current, and so it is inferred that with the 80% rule (from NEC), you would use about a 60a breaker on a 4 AWG wire.

So you'll have to see if the wire you have there already can fit into the EG4 input connection lugs.

 

[JonnyWatt]

FYI to help others and/or be corrected if doing it wrong:

I am about to go live (with load) on my two EG4 6500ex inverters in parallel for 240V split phase. I have 10KW in solar panels (qty 22) and 30KW in Lifeforce batteries (qty 6). I originally was going to be completely off-grid but now see getting more shading on my 460W Blue Sun panels than anticipated and need grid assist for days my solar panels and batteries are not enough to power 60A loads most of the day. Both my off grid solar load center and main grid utility load center are both 50ft away from inverters.

To provide grid assist from main utility, I purchased 50ft 6-3 romex and then split 6-3 to each inverter using Recoil DB13P 3 Way Power Distribution Blocks from Amazon - https://www.amazon.com/dp/B097T3BWNQ?ref=ppx_yo2ov_dt_b_product_details&th=1 [I imagine most would use bus bars to split 6-3 cable to each inverter, but I wanted to avoid having to crimp ring terminals onto wires, so I bought the distribution blocks instead which only require alan wrench to tighten down cables.] I also used these same distribution blocks to receive inverter OUTPUT from both inverters to a/c disconnect toward load center; however, for output, I used more expensive single strand 4AWG wires. The distribution blocks take up to 4AWG wires. In both cases, I am currently using 60A double breakers at both main utility panel (grid assist) and solar load center. My main point is this is an alternative way to split wires to/from load centers to TWO inverters.

I may back the grid assist 6-3 wire down from 60A breaker to a 50A breaker, but not sure I need to. I'm wondering if the inverter input limits the flow so that a 60A breaker is sufficient protection.

I am open to suggestions or correction if the pros think this is not the best approach.