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Generator Tie-In 6kXP (Parallel Config.)

JBoffgrid2022

Solar Enthusiast
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Oct 28, 2022
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Hello All!
1. Looking for some general guidance on methods to provide a back up power source for my three EG4 6kXP's in parallel. The instruction manual only gives the following guidance (below) but fails to explain in detail how this could be implemented in a real world situation in parallel configuration. Would I be bringing my generator wires into a separate panel, then into the inverter sub panel? Or would I bring the generator wires straight into the inverter sub panel? I was hoping someone on here has been able to install a generator hook-up in a similar situation and has also been able to get it to pass their local code enforcement.

2. Does anyone here have recommendations on a propane fueled generator size? The manual states the generator should 150% larger than the total inverter bank which in my case is would be at least a 25kW gen.

Thank you all!

EG4 Manual:
4.7.3 GENERATOR AC CONNECTIONS
Please follow the steps listed below to ensure your Generator connections are installed correctly.
Note: If running more than one inverter in the system, you must wire the generator to provide power to every inverter running in parallel for the inverters to function as intended.

Step 1: Before making any wiring connections, be sure to have the inverter(s) powered off, the generator powered off, and all circuit breakers open (off) to prevent damage to the unit.
Step 2: Properly identify the generator’s output lines. By US wiring standards, L1 wire will be black, L2 will be red, Neutral will be white, and ground will be green. Once identified, remove ≈10mm from the insulation sleeve on the wires.
Step 3: Ground the generator’s output ground to the Ground Bus (labelled PE) of the inverter.
Step 4: Install L1 to the GEN port’s L1 terminal, then install L2 to the GEN port’s L2 terminal. Next, fasten the Neutral wire from your generator into the N-BUS (Neutral Bus).
 
The generator must be tied into the gen port on all 3 of the inverters and the inverters configured for generator on the gen ports.
The dry contacts on the master inverter should be used to start/stop the inverter.
Now.... what is the best way to physically wire the generator power output into the Gen ports? I would probably use a separate junction box where I split the Wires from the generator into 3 wires for routing to the inverters. Presumably it will be reasonably large generator with large wires. Something like this for each line would work:

 
Thank you for the input! I will run this by my electrician to see what his thoughts are. It would seem we could "get away with" a smaller generator and still provide enough energy to keep the inverters happy. I'm not sure if it matters but should I avoid a generator that has a built in inverter? In other words, is it safe to stack a built in inverter and wire that into a chargeverter? I would imagine this isn't a good idea but thought I'd ask. THank you again
 
That is an excellent way to use a smaller generator on a large system. However for a 7KW generator, a couple chargevertes might be needed.
Nope. Run generator at 70%, or about 5kW, which is the limit of the cv. If you want to be even more careful, get a 5kW, and run the cv at 80% too.
 
Thank you for the input! I will run this by my electrician to see what his thoughts are. It would seem we could "get away with" a smaller generator and still provide enough energy to keep the inverters happy. I'm not sure if it matters but should I avoid a generator that has a built in inverter? In other words, is it safe to stack a built in inverter and wire that into a chargeverter? I would imagine this isn't a good idea but thought I'd ask. THank you again
Not good to parallel generators, unless designed to be paralleled. With a CV, no need to spend extra for inverter generator. Also, your decision if you need more power to get 2 small generators each with its own cv, or one larger one with two cv's. Redundancy is good, especially for off grid.
 
Backing up a bit: What do you expect the generator to power? If you want to power everything the inverters are powering *And* charge the batteries, we are back to needing a crazy large generator and tying it directly to the inverters.

However, if you are looking at the generator as an emergency backup for when the batteries get low the chargeverter and a smaller generator might be a good way to go. If the batteries get low and the genertor kicks in.... you will have to be conservative on your power usage till the batteries get charged up.
 
That's very helpful! I did not know the battery/chargerverter/generator could work as a unit. So it sounds as though the chargeverter would monitor the SOC on the batteries and send the signal to start a generator which would then charge batteries then shut off once they reach 100%, correct? If the generator's sole purpose was to do this I wouldn't need a massive and expensive generator. I actually already own a 12kRES Kohler, I think this would work.
 
That's very helpful! I did not know the battery/chargerverter/generator could work as a unit. So it sounds as though the chargeverter would monitor the SOC on the batteries and send the signal to start a generator which would then charge batteries then shut off once they reach 100%, correct? If the generator's sole purpose was to do this I wouldn't need a massive and expensive generator. I actually already own a 12kRES Kohler, I think this would work.
I think the Version 2 of the chargeverter has generator start capabilities. Set each at 80a, and that will be about 70% load on the 12kW generator, which is a good operating point. You can also boost both to 100a if you are in a hurry.
 
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Is this what you're referring to?
If so, would this be able to be tied into three separate batteries? I was hoping to tie three EG4 wallmounted batteries to three EG4 6kXP inverters.

 
For clarity, here is my entire setup:

48 Aptos 400W Bifacial Panels (6S8P)
3 EG4 6kXP Inverters in parallel
3 EG4 Wallmounted Batteries (Tied into each inverter respectively)

Optional back up power from generator to supply power on long cloudy periods during winter months.

Generator may not be necessary simply because I don't know how much power my array will end up putting out yet.
 
3 EG4 Wallmounted Batteries (Tied into each inverter respectively)
Why do you want to keep the batteries separate? Typically, people tie them together. Will the inverters be totally separate or will the outputs be paralleled? If paralleled, does the 6000XP support separate batteries.?

If you keep the batteries separate, you will need 3 chargeverters.

BTW: Check with EG4 to be sure, but I believe the gen start/stop can be controlled by the inverter while the generator power is delivered via a chargeverter.

1726952532762.png

This allows the Chargeveter to be controlled based on the same SOC as what the inverter is seeing from the battery.
 
I would have three inverters and three batteries connected to each inverter.
My original question was about how I could tie in a generator to this setup. If purchasing a large (25kW) generator could be avoided, could I use a smaller generator with a chargeverter and if so, how should I make these connections?
 

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I would have three inverters and three batteries connected to each inverter.
My original question was about how I could tie in a generator to this setup. If purchasing a large (25kW) generator could be avoided, could I use a smaller generator with a chargeverter and if so, how should I make these connections?

1) if the batteries are all separate, it will require 3 chargeverters, one for each battery.
2) In the diagram, one of the inverters is labeled 'master'. That implies the ouputs of the inverters are paralleled. Please check with EG4 whether the seperate batteries is supported. I once heard that it was not supported, but I recently noticed there is a config setting for separate batteries.
3) If running 3 separate chargeverters to 3 independent generators Batteries, control of the generator becomes 'interesting'. If using the newer chargeverter that can control a generator with a dry contact output, I suppose you can parallel the dry contacts. If any of the chargeverters are asking for generator power, the generator will run, but only the ones needing power will charge it's battery.
4) You will need to set the current on each chargeverter at a level that will not be too much for the generator when all three chargeverters are running.

Unless there is a reason the batteries must be separate, I would buy the paralleling kits to tie them together. It simplifies everything.
 

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