Generator Sizing (2 EG4 6000XP in Parallel)

[JBoffgrid2022]

Hello!
Looking for some advice on generator sizing for (2) EG4 6000XP's in parallel. I have a propane powered Kohler 12kW RES off grid generator installed at my off grid camp and would hate to have to sell that and install a new larger generator if I don't have to. The total size of the two inverters I am installing is 12kW. The manual that came with the inverter only gives instructions for one inverter. It mentions two things:
-1. Get a generator that is 150% larger than the inverter (this would equate to a 18kW generator for both inverters if my understanding and math is correct).
-2. Connect the generator input lines to all inverters in parallel. This is what is making me think I will need a bigger generator to properly supply enough power to charge the battery bank and supply the load to the main panel/house.

Any advice would be appreciated! Thank you.

 

[12VoltInstalls]

Can you not adjust the charging amps to plateau lower than max capacity?

I’m having difficulty imagining how a properly designed solar power system would need more capacity than the max of the system to charge batteries. Or do you actually use 12kW of loads continuously on a regular basis?

I think load reduction and management would be preferred over fitting a NASA-sized generator.

 

[jimf909]

The general rule of thumb is to have a generator that's larger than the inverter capacity to ensure that the generator can support loads and charge batteries at the same time. This can also help minimize generator overloads if the inverter hasn't been set up to limit draw from the generator.

In real-life, how much of your 12kW do you actually typically use? If your average load is 3kW that leaves a lot of capacity for your current generator to charge batteries.

Alternatively, you can connect your generator to a separate battery charger and only use the generator to charge the batteries and leave the inverters on single duty of inverting the battery power to AC. This also eliminates passing possibly dirty power from the generator to the house circuits. This is what I have done using an EG4 100 amp battery charger and an inexpensive open frame generator.

 

[JBoffgrid2022]

Can you not adjust the charging amps to plateau lower than max capacity?

I’m having difficulty imagining how a properly designed solar power system would need more capacity than the max of the system to charge batteries. Or do you actually use 12kW of loads continuously on a regular basis?

I think load reduction and management would be preferred over fitting a NASA-sized generator.

Re: "Can you not adjust the charging amps to plateau lower than max capacity?"
I'm unsure how to find the answer to that question, partly because I don't know what you mean, and partly because I don't know where to look lol. I can start by looking at the manual again to see if there is any mention of changing this setting.

I wouldn't be using more than 8kW at the same time continuously either.

I believe the inverters need to have enough power to both run the inverter's load AND charge the battery bank simultaneously. The inverters have a minimum input voltage/amperage to be able to switch over to charge mode. Based on my generator's output, 12000w/240v = 50amps. One inverter's max input is 30amp, two would be 60amp max input. But again, the question remains, what is the minimum acceptable input for the generator? To your point, I would imagine that would depend on the expected load the inverters will have to supply to the camp.

Here's the manual if you want to look it over for yourself:

https://eg4electronics.com/backend/wp-content/uploads/2023/10/EG4-6000XP-Manual.pdf

 

[JBoffgrid2022]

The general rule of thumb is to have a generator that's larger than the inverter capacity to ensure that the generator can support loads and charge batteries at the same time. This can also help minimize generator overloads if the inverter hasn't been set up to limit draw from the generator.

In real-life, how much of your 12kW do you actually typically use? If your average load is 3kW that leaves a lot of capacity for your current generator to charge batteries.

Alternatively, you can connect your generator to a separate battery charger and only use the generator to charge the batteries and leave the inverters on single duty of inverting the battery power to AC. This also eliminates passing possibly dirty power from the generator to the house circuits. This is what I have done using an EG4 100 amp battery charger and an inexpensive open frame generator.

Re: "Alternatively, you can connect your generator to a separate battery charger and only use the generator to charge the batteries and leave the inverters on single duty of inverting the battery power to AC. This also eliminates passing possibly dirty power from the generator to the house circuits. This is what I have done using an EG4 100 amp battery charger and an inexpensive open frame generator."

I love this option, if all else fails and the inverters do not accept the generators power supply, I could always bypass the inverter and charge the batteries. I am not concerned with the generator providing dirty power, they have shown stable clean power signal for almost two years charging my older setup.

 

[dougbert]

same here on an external charger

get 2 chargeverters and use them (at the same time from the same generator) to charge the battery directly from the generator and totally bypass the EG4 6000XPs saving them for inverting only

in my build thread, post #1 I layout my schematic what I have done, down a page or 2, look for the AC SIDE title

and here for some pictures

 

[dougbert]

and if you get really serious

this youtuber, is on this forum and owns/runs Current Connected (or close to that)

 

[jimf909]

I am not concerned with the generator providing dirty power, they have shown stable clean power signal for almost two years charging my older setup.

Yeah, I'm guessing your Kohler provides clean power.

However, should the Kohler go down and you need to run a cheap backup generator (cheap purchase, cheap rental, borrowed, etc.) running that cheap backup generator to the battery charger eliminates the concern of sending that dirty power to any sensitive electronics connected to the house circuits.

Food for thought.

 

[12VoltInstalls]

start by looking at the manual again

There ‘should’ be a setting among the several that control when and how ‘grid’ power is utilized- in your situation the generator is ‘grid.’

the expected load the inverters will have to supply to the camp

In real-life, how much of your 12kW do you actually typically use?

For a camp 50A@240 is A LOT of power.

(generator has) shown stable clean power signal for almost two years charging my older setup

So unless you’ve added a large amount of new loads, my observation would be that if it was enough before the AIO upgrade, it will still be enough- you just need to manage the power utilization within the EG4 AIO settings.
But yes: the question is do you actually need/use 12kW continuously? I doubt that you do for a camp.

Based on my generator's output, 12000w/240v = 50amps. One inverter's max input is 30amp, two would be 60amp max input. But again, the question remains, what is the minimum acceptable input for the generator?

“One inverter's max input is 30amp, two would be 60amp max input”
That is the answer. So limiting to 25A/ea is the logical conclusion.

cheap backup generator to the battery charger eliminates the concern of sending that dirty power to any sensitive electronics connected to the house circuits

Do these do direct pass-through/bypass of input? Maybe I’m in error but I thought these as well as the 6548’s and their ilk runs all input through the inverter output. Though admittedly I’m unfamiliar with EG4 and only just now studying up on 6548 because I’m helping someone install one once it arrives next week.
At least for the 6548 and 6048 there was a usage / feature video I watched a week or so back that said that all incoming power gets utilized through the inverter (thereby filtering whatever power) and I understand the EG4’s are a proprietary version of these economical units.

I will happily accept being corrected if I am wrong that input power is isolated.

Back to the originally scheduled program:
I’m stuck on the idea that if the 12kW generator was sufficient before and loads were not added it is still sufficient- the unit’s parameters and settings need to be configured to utilize the specific equipment being incorporated.

 

[JBoffgrid2022]

Thank you this well thought out reply @12VoltInstalls !
If I were to in fact leave the generator and provide back up power to both newly installed inverters, what are you thoughts on splitting service wires coming from the generator? I currently have the following wires running from the generator: (All 6AWG) L1, L2, N, & Ground
Would these wires land in a small 50 amp sub panel, then break off into two separate leads, each on a 25amp breaker? (One for inverter 1, one for inverter 2).

 

[12VoltInstalls]

Thank you this well thought out reply @12VoltInstalls !
If I were to in fact leave the generator and provide back up power to both newly installed inverters, what are you thoughts on splitting service wires coming from the generator? I currently have the following wires running from the generator: (All 6AWG) L1, L2, N, & Ground
Would these wires land in a small 50 amp sub panel, then break off into two separate leads, each on a 25amp breaker? (One for inverter 1, one for inverter 2).

I can’t answer
1) without reading the manual
2) without knowing the local AHJ
3) without knowing what your insurance company wants to see

Having said that - if there are two inverters connected for split phase operation the manual will say how to wire them. If the
/a single unit is split phase the manual will cover that.

Would these wires land in a small 50 amp sub panel, then break off into two separate leads, each on a 25amp breaker

That would work imho. Just set the units’ grid/input charging current limits accordingly. Solar can remain as God intended.

 

[jimf909]

Do these do direct pass-through/bypass of input? Maybe I’m in error but I thought these as well as the 6548’s and their ilk runs all input through the inverter output. Though admittedly I’m unfamiliar with EG4 and only just now studying up on 6548 because I’m helping someone install one once it arrives next week.
At least for the 6548 and 6048 there was a usage / feature video I watched a week or so back that said that all incoming power gets utilized through the inverter (thereby filtering whatever power) and I understand the EG4’s are a proprietary version of these economical units.

I will happily accept being corrected if I am wrong that input power is isolated.

I don't know. I was making an assumption. Thanks for calling it out.

Pages 14-16 of the manual mentions generator power "pass through" but I haven't taken the time to determine if passing through the generator power directly is what is meant or if it's being passed through the inverter.

 

[12VoltInstalls]

haven't taken the time to determine if passing through the generator power directly is what is meant or if it's being passed through the inverter.

Someone that knows the unit will likely correct my assumption if necessary.

 

[JBoffgrid2022]

I will share this post with one of the EG4 techs that are here at this forum. In the meantime, I will leave the existing generator as is and not make any connections until I get a better sense of the architecture of the inverters.

@EG4_Jarrett could you take a quick look over this post regarding generator sizing and recommended wiring for two EG4 6000XP's in parallel?

 

[EG4_Jarrett]

Sorry, I'm trying to talk to text this while in Walmart, so bear with me if something doesn't make sense.

Ok, so if you want to use the same generator that you have, that's fine. The manual does state that you should size the generator for 150% of output of the inverter, but there are other ways of handling this. And selling a generator just to buy a new one would be quite a hassle. I just wouldn't try to run all 12kw off of it.

There are gen settings in the inverter that you can set the size of the generator, I would just set that to 10kw. That way, you don't max out the generator. Maxing out the generator will cause the output power to have a higher amount of harmonic distortion. The heavier the load you power with the generator, the dirtier the power.

As far as wiring recommendations, I don't know what the local AHJ wants to see or what codes they are super picky about. I would run to a subpanel and split off to both inverters using breakers. Or you can use taps to go to both inverters, but like I said, I'm not sure how picky your AHJ is. Some will let you get away with murder, and some will flip out over a sticker.

The inverter does allow for bypass as well. Grid and Generator should both bypass if it's called for.

 

[JBoffgrid2022]

Thank you @EG4_Jarrett !!
Your message came across perfect too
I will look this over and let you know what i end up doing.

 

[12VoltInstalls]

The inverter does allow for bypass as well. Grid and Generator should both bypass if it's called for

Probably can guess the answer but explicitly answer this:
Does it literally pass gen/grid input or can it be set to only derive from the onboard inverter (aka battery power). Not 100% important to this conversation but would like to know (I’ve seen some youtube reviewers that claim all output is via inverter and most don’t mention it other than the phrase ‘pass through.’)

 

[EG4_Jarrett]

Probably can guess the answer but explicitly answer this:
Does it literally pass gen/grid input or can it be set to only derive from the onboard inverter (aka battery power). Not 100% important to this conversation but would like to know (I’ve seen some youtube reviewers that claim all output is via inverter and most don’t mention it other than the phrase ‘pass through.’)

The inverter can run Grid or Gen in bypass, meaning that the inverter doesn't affect that power. There is a 50a breaker on the output of the inverter though. You can also power loads with Solar/Battery. It just depends on what you want it to do.

 

[Mattalinguist]

Hey guys. I'm finalizing design on a comparable system. I'll be using 2 EG4 6000XP in parallel with a backup generator. The generator will be new so I'd like it to be sized according to EG4 6000XP specs. Manual says the following on 5.8.1 - 2 Inverters in Parallel generator needs to be greater than 15kw. Any advantage to oversizing the generator beyond 15kw? The generator input on each inverter is 30amps.

 

[12VoltInstalls]

Any advantage to oversizing the generator beyond 15kw?

There’s a few opinions on this but 15kWh to feed a pair of 30A loads seems more than adequate in my opinion.