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48V Offgrid Solar Power System EG4 6000XP, one or two inverters?

MainerUSNR

New Member
Joined
Jan 6, 2024
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17
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Maine
I'm in the planning stage, I am going to build a battery backup system using a EG4 6000XP inverter and three EG4 LL batteries. Later I will add solar, initially about 4kw string. Now I am wondering if I should add a second 6000XP inverter and a fourth battery with the intent to have two batteries per inverter and 2KW solar per inverter. I have watched several of Will Prowse's and others, videos. Any ideas? Thank you.
 
Four 5kWh batteries with 4kW of panels is mildly tight.

What is the daily and overnight kWh of usage? There’s also a factor of two AIO’s and the idle consumption.

If all you need is 10kWh under one unit is the second unit necessary? Do you want or need more than a day’s worth of storage? Is this truly offgrid or do you have powerco and just want to offload some usage or exclusively want ‘backup?’

Need to know the kWh demand to say anything useful.
 
You might consider a common battery bank rather than separate ones. Even if you run 1 PV array to each AIO for other reasons such as placement.
Even + to + and - to - loop(s) could do that easily, right?
To OP: that’s in case one phase has a higher loading so the batteries stay balanced per phase- sorta same for charging.
 
Thanks for the quick feedback, wow! Ok, in reading my initial post, I failed to say I am trying to make a home battery back up to run the house for a 6-12 hours. I will be able to run the water-pump, a couple freezers, a refrigerator and some lights overnight. I intend to use the batteries during power outages during the night so I don't have to run a generator while sleeping.

In 2023, we ran the generator 72 hours, in 2022 34 hours, 2021, 32 hours and in 2020 we ran the generator 115 hours. Those are generator running hours, not how long the power was out. Many times we sleep with the generator not running, but when it is really hot or cold we will run it for an A/C or K-1 heater to maintain comfort.

- I am using grid power to keep the batteries charged, so when I lose grid power, I will using a generator connected to EG4 ChargeVerter to charge the batteries and will eventually supplement the generator with solar.

- I did like the idea to just connect the solar to one inverter.

- Power Usage - We went to Florida a couple years ago and averaged 6.19 & 6.03 Kwh per day with everything on as usual, we average 24-26 Kwh per day when we are present. I believe with the 3 or 4 batteries we can get through the night easily and I can recharge them in the morning via generator, solar or grid power if it is restored.
 
...

- Power Usage - We went to Florida a couple years ago and averaged 6.19 & 6.03 Kwh per day with everything on as usual, we average 24-26 Kwh per day when we are present. I believe with the 3 or 4 batteries we can get through the night easily and I can recharge them in the morning via generator, solar or grid power if it is restored.
You will want to have a better measurement of your load during hours that you do not use any charging. What typically catches people in the Winter months, that rely on solar, is the longer period of no charging input due to short days. Also there can be an increase loading as more lights and other things are used.

Batteries are a storage system that is inexact in terms of capacity. SOC and capacity are related but other factors are at play such as ambient temperature, age of batteries and cell chemistry. As people found out in their EV's in Chicago area recently, the distance they thought they should get was not the actual distance they were getting in the frigid cold and charging was a pain. Being at 100% SOC does not mean much if your capacity is reduced or the load is higher than anticipated.
 
You will want to have a better measurement of your load during hours that you do not use any charging. What typically catches people in the Winter months, that rely on solar, is the longer period of no charging input due to short days. Also there can be an increase loading as more lights and other things are used.

Batteries are a storage system that is inexact in terms of capacity. SOC and capacity are related but other factors are at play such as ambient temperature, age of batteries and cell chemistry. As people found out in their EV's in Chicago area recently, the distance they thought they should get was not the actual distance they were getting in the frigid cold and charging was a pain. Being at 100% SOC does not mean much if your capacity is reduced or the load is higher than anticipated.
???? I'm confused.
You will want to have a better measurement of your load during hours that you do not use any charging.
With refrigerator, freezers and heat running for two months we averaged about 6Kwh per day. We weren't charging anything and the system I am designing is essentially for use overnight while we are sleeping, i.e low occupant usage time.
 
???? I'm confused.

With refrigerator, freezers and heat running for two months we averaged about 6Kwh per day. We weren't charging anything and the system I am designing is essentially for use overnight while we are sleeping, i.e low occupant usage time.
Based on your numbers at 6kWh per day you can assume an average of 6000wh day/24h= 250wh each hour. How long is nighttime? 12 hours? Therefor you have 12h X 250wh/h=3kWh use from battery. Now when charging you need to supply that back plus carry other loads during charging time.

What trips people up is forgetting that batteries are not a power supply but just a storage.

ETA: I apologize if this is already obvious for you. I put the information out there so others can see it when browsing through the Forum.
 
Based on your numbers at 6kWh per day you can assume an average of 6000wh day/24h= 250wh each hour. How long is nighttime? 12 hours? Therefor you have 12h X 250wh/h=3kWh use from battery. Now when charging you need to supply that back plus carry other loads during charging time.

What trips people up is forgetting that batteries are not a power supply but just a storage.

ETA: I apologize if this is already obvious for you. I put the information out there so others can see it when browsing through the Forum.
I'm confused again, if I have three 5kWh batteries (15kWh) wouldn't that last overnight or even two or three days based on a 6Kwh usage per day, let alone over night (be it 6-12 hours)? Is there something I'm missing? Again, I'm charging the batteries back up the next morning with either a generator or grid power, or eventually solar too.
 
I'm confused again, if I have three 5kWh batteries (15kWh) wouldn't that last overnight or even two or three days based on a 6Kwh usage per day, let alone over night (be it 6-12 hours)? Is there something I'm missing? Again, I'm charging the batteries back up the next morning with either a generator or grid power, or eventually solar too.
Sorry about confusion. Certainly if you have enough battery to make it you have enough. Do not forget to account for extra loading based on inverting DC to AC.
 
Sorry about confusion. Certainly if you have enough battery to make it you have enough. Do not forget to account for extra loading based on inverting DC to AC.
That's cool, I just want to have enough juice to get through the night mostly and not have to run a generator at night when sleeping/
 
I am basically doing the same thing....6000XP inverter, but I went with an EG4 PowerPro 14.3 Kwh battery instead of rack batteries. I am still wiring, but will be up and running this week. The battery is really nice and I may add a second one. I am going to add an EG4 Chargeverter so I can charge the battery with my WEN 11Kw propane generator also.Solar is in the near future, but I am in a fight with the local authorities.Where in Maine are you?
 
will be able to run the water-pump
Nice that’s split phase.

Solar panels- I know you said future- will at least let you recoup a bit of expenses each month by diverting usage to solar input. With the above…
you have 12h X 250wh/h
…by incorporating solar sooner than later even your:
we average 24-26 Kwh per day when we are present
…would be ~40-50% offset by running, say, a dozen 300W panels and plumbing through the inverter set up to be prioritized
1) solar
2) grid / powerco
3) battery
…often denoted “SUB”

Just thoughts- payback would be “slow” but it’s way faster to get something than to recoup nothing LOL

I don’t know anything about the 6000xp’s handling of ‘sharing’ with grid if the load exceeds capacity or what have you.

Just my thoughts and opinions ymmv
 
Nice that’s split phase.

Solar panels- I know you said future- will at least let you recoup a bit of expenses each month by diverting usage to solar input. With the above…

…by incorporating solar sooner than later even your:

…would be ~40-50% offset by running, say, a dozen 300W panels and plumbing through the inverter set up to be prioritized
1) solar
2) grid / powerco
3) battery
…often denoted “SUB”

Just thoughts- payback would be “slow” but it’s way faster to get something than to recoup nothing LOL

I don’t know anything about the 6000xp’s handling of ‘sharing’ with grid if the load exceeds capacity or what have you.

Just my thoughts and opinions ymmv
Hi, I am not looking so much for a recoup or pay back, just saving run time on a generator and me having to get up at night to start a generator. Plus, when the you-know-what hits the fan I'll have some power rather than no power at all other than a twenty year old generator droning on for hours on end. Stealthy power usage and generation may come in handy.
 
Stealthy power
…requires panels. :)
not looking so much for a recoup or pay back
That’s a very fortunate situation to be in.

For me it does not compute, though. Not built that way. I’ll spend money to make money but I seldom if ever spend money on anything other than groceries, tires, heating fuel: no choices there LOL
Whether a little while back when I did $85k or 2010 when I only did $32k I’ve always operated the same - everything from groceries to tools to fishing lures to solar: ROI is a high priority. I’m not cheap but I’m not a spender. I’m a value consumer; high end tools, low cost trash bags.
 
I'm confused again, if I have three 5kWh batteries (15kWh) wouldn't that last overnight or even two or three days based on a 6Kwh usage per day, let alone over night (be it 6-12 hours)? Is there something I'm missing? Again, I'm charging the batteries back up the next morning with either a generator or grid power, or eventually solar too.
For what you wish to do, you should be fine. My only modest concern is the starting current of the well pump if a fair number of other loads are also on (fridge, freezer, furnace motor, etc.), as many well pumps can create a very large draw for a second or two. I don't think we yet know whether/how well the 6000XP can handle that in terms of real world experience, although I seem to recall Will testing one with a car lift. It's a small worry to me, but worth noting. Please report back on how you like the 6000XP. I'm considering two of them for a new house in Waldo county later this year.
 
For what you wish to do, you should be fine. My only modest concern is the starting current of the well pump if a fair number of other loads are also on (fridge, freezer, furnace motor, etc.), as many well pumps can create a very large draw for a second or two. I don't think we yet know whether/how well the 6000XP can handle that in terms of real world experience, although I seem to recall Will testing one with a car lift. It's a small worry to me, but worth noting. Please report back on how you like the 6000XP. I'm considering two of them for a new house in Waldo county later this year.
I am saving my $$ for the build.

I will say that I run the whole house on a Generac 7550XL generator when power is out using the 30 amp 220 volt plug during power outages. The 7550 can take a 12k surge. That has me wondering whether I should use two 6000XPs and four batteries.
 
I am saving my $$ for the build.

I will say that I run the whole house on a Generac 7550XL generator when power is out using the 30 amp 220 volt plug during power outages. The 7550 can take a 12k surge. That has me wondering whether I should use two 6000XPs and four batteries.
I think you and I are having some of the same things to ponder for new builds. I think my use is going to come in at about 10 kWh per day, but may be as low as 6 some days, when in "not using the mini-splits" season. Personally, I'm planning on either Victron or EG4 6000 XP. If I go with the latter (starting to lean that way), I'll go with two of them and may buy a third to keep as a spare, simply because they're not expensive and I learned from the Covid supply shortages (two is one, one is none).

I also have a 12KW generator at the current house and we've never had a problem when using it for days at a time. I think I'll start with 15kwh of batteries, with room to expand up to 45. I can pay for a lot of battery-recharging propane before I equal the cost of an additional battery bank, so am eager to see how we do with our first bank of 15 kwh. BTW, for well pump, check out Grundfos SQ.
 
I think you and I are having some of the same things to ponder for new builds. I think my use is going to come in at about 10 kWh per day, but may be as low as 6 some days, when in "not using the mini-splits" season. Personally, I'm planning on either Victron or EG4 6000 XP. If I go with the latter (starting to lean that way), I'll go with two of them and may buy a third to keep as a spare, simply because they're not expensive and I learned from the Covid supply shortages (two is one, one is none).

I also have a 12KW generator at the current house and we've never had a problem when using it for days at a time. I think I'll start with 15kwh of batteries, with room to expand up to 45. I can pay for a lot of battery-recharging propane before I equal the cost of an additional battery bank, so am eager to see how we do with our first bank of 15 kwh. BTW, for well pump, check out Grundfos SQ.
You said "I can pay for a lot of battery-recharging propane before I equal the cost of an additional battery bank", but the last couple big storms around here a few years ago there was so many trees down that main and secondary roads were impassable and power was out for three or four days, no one was delivering propane or anything and people ran out of propane. I have a good old gas generator and we were fine. I'm adding layers and redundancies and I agree "two is one, one is none".
 
You said "I can pay for a lot of battery-recharging propane before I equal the cost of an additional battery bank", but the last couple big storms around here a few years ago there was so many trees down that main and secondary roads were impassable and power was out for three or four days, no one was delivering propane or anything and people ran out of propane. I have a good old gas generator and we were fine. I'm adding layers and redundancies and I agree "two is one, one is none".
We have two 500 gallon tanks for the generator. When full, we can last 47 days. I use same tanks for the garage heater and some other light use things. I checked yesterday and we were down to 64% in one, 72% in the other, so a bit over 30 days of generator fuel. Time to get the truck out for a refill. When I hear of people getting down to a few days supply I just scratch my head. Suburbia this ain't.

We also have two backup gas gennies but I keep only ~40 gallons of treated fuel for those. Buildings each have three sources of heat as well. Mini-splits - propane - wood. Four fridges / freezers across two dwelling units. Two separate internet feeds (Starlink & a WISP). Backup router configured and waiting.
 
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Buy one 6000xp, but plan install for two. If one isn't sufficient, you can easily parallel a second. Or add batteries to the single.

BTW: max AC passthrough for one unit is 37.5a. Make sure that is enough for on grid usage.
 

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