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Off Grid AIO sweet spot? Double-check my math here please...

Rednecktek

Rednecktek

Solar Wizard
Joined
Sep 8, 2021
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On a boat usually.
So I've been looking at properties out in Montana and because I work for a living the only things I can find are all off-grid with estimates over $1 million for grid, so no.

The goal would be to provide a full normal 200a power supply to the property via stacked inverters for the least amount of money. I'm thinking of a 40ft container along the lines of what Ambition Strikes did for their solar power center, so space isn't really a concern. Here's my rough numbers thinking:

EG4-6000xp provides 25a @ 240v for about $1500 x 8 units = $11,200 for 200a (includes breakers)
EG4 18k provides 50a @ 240v for about $5000 x 4 units = $20,000 for 200a
NHX 10kw provides 40a @ 240v for about $2200 x 5 units = $11,000 for 200a

So since wall space isn't really an issue, the EG4 seems to be the sweet spot for getting 200a of off grid power. Many of the other brands are significantly more expensive so I didn't bother throwing them in the list.

Am I missing something in my math?
 
I like my conex set up. But I can’t even imagine needing that much power.

Wish I’d insulated it first thing. It filled up fast.
 
The ability to produce 200 amps is a bit high. I'd start off with a predicted power needs audit, add 20%, and make it expandable if needed later.
 
As much as I like cooking on a gas stove, getting propane delivered is a questionable thing so I'm having to assume high for electric stove & oven, multiple aircon heat pumps, deep well pump, welders, shop tools, etc. A wood stove is nice but doesn't always do much for the bedrooms so there will likely be quite a few heat pumps involved. I figured 200a was a good goal and should leave me realistic overhead. For math planning it seemed like a good starting point.

Trying to estimate power needs before I know what I have for buildings and being at sea for 6+ months at a time really mess with math.
 
Remembering back to the time I lived in Montana (just North of Billings) for a couple of years I never needed Aircon. It was rare to even get in the 90's and usually it would be very dry so not unmanageable with shade and fans. Winter however is just brutal for cold. The home I had back then was a earth berm type which help interior temperatures and was heated with an air tight woodstove.

Which part of Montan are you looking at?
 
Mattb4 said:
Which part of Montan are you looking at?
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I'm hoping to find something in the west or southwest ends, not really that picky as to where due to finances and having to plan ahead a few years. After the divorce I'm starting over so it'll be 3 years before I can walk into a bank and ask for a loan, but the more I have in my head now the less time it'll take to get the lights on when I do find something (i.e. if I can drive out to the new place with a truck full of inverters, sub panel, and a spool of wire rather than having to buy them all at once the day I sign papers). Plus if I can figure out what I'll need now I can start buying parts as I get ashore and not have to find all the money up front. I don't figure AIO's are going to make a huge leap in technology for the dollar in that time.
 
I have no issues heating a poorly insulated house with 2 floors with a wood stove in northern Minnesota where it is typically much colder than western Montana. I use a kitchen queen stove which also means you don't need to waste electricity cooking in winter either. Also if you look at the dew points for Montana on any given day during the summer you'll see how much better they are then most of the country. It is 88°F in Great Falls right now with only a 40°F dew point.
 
You’re still going to want a backup generator so a 500 gallon propane tank and planning to get it topped off once a year would allow a gas stove and save a lot of electricity
 
Rednecktek said:
Many of the other brands are significantly more expensive so I didn't bother throwing them in the list.
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What about the brands that are significantly cheaper? Like 10KW for ~$1200 cheaper

Who knows where technology and prices will be in a few years, you could save or lose thousands buying now.
 
Rednecktek said:
I'm hoping to find something in the west or southwest ends, not really that picky as to where due to finances and having to plan ahead a few years. After the divorce I'm starting over ...
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Reminds me of the Unibomber. He lived in southwest Montana if I recall. A small wood shed with no amenities. Rode a bicycle into town for supplies.

You may not need all that large of a household Service. My typical usage before I went solar was about 10-15kWh per day here in AR.
 
42OhmsPA said:
What about the brands that are significantly cheaper? Like 10KW for ~$1200 cheaper
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Like who? Links please?

Mattb4 said:
You may not need all that large of a household Service. My typical usage before I went solar was about 10-15kWh per day here in AR.
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I probably won't need it, but this was more about the math and choosing a common point for comparisons than anything else. Having to leave some electrical systems on while I'm away brings its own paranoias...

Brett V said:
You’re still going to want a backup generator so a 500 gallon propane tank and planning to get it topped off once a year would allow a gas stove and save a lot of electricity
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If I get a backup generator involved, it'll likely run on diesel or the like. I don't want to have to rely on someone's service if I can avoid it. As I've learned with my camp, winterizing perfectly is nigh on impossible to predict everything.

42OhmsPA said:
Who knows where technology and prices will be in a few years, you could save or lose thousands buying now.
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True enough, I'm just thinking that the technology isn't likely to get that much better and I can afford a couple 6000xp's and a battery every time I come home over the next few years, but trying to buy 6 or 8 plus batteries plus panels plus starlink plus closing costs plus container plus well plus plus plus all at once is much more difficult.

I have to think of it like a personal investment account. If I don't put the money into the account every payday, that money WILL find somewhere else to be. So if I don't buy what I know I'll be able to use as I go along, I won't have the money to do it all at once later. My rough math says I can afford a 6000xp and build a 48v 304Ah battery every 8 months, so I should be able to swing 4x batteries and 4x inverters in stock before I have to worry about the rest of the system.
 
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200a at 240V that's almost 50kW of peak power. Or if let's say you go for 8x6kW AIOs and you do run all of them it'll be ~400W of just idle consumption. I wouldn't want to run 400W just because I might use 50kW of power (especially in winter)

An idea of a power audit was already mentioned. I have a smallish house (not in the US) but 20kW is all I need (tankless water heater excluded) and I run pretty much everything on electricity well pump, induction hob and (as of recently)heat pump for AC included. I do use led lighting though.

If I was building from scratch for off grid I would put a huge insulated domestic water tank in the ground and heat water with a heat pump (it is in my future).

If I really needed that much off-grid power I'd go for EASUN SMW 11k twins(11kW and $1200 a pop for 240V EU variant - it can run parallel or in 3 phase- one would have to check if they have a split phase model for the US or can the same-device run with different settings).

Edit: I'm not seeing a split phase model for EASUN. So probably better to stick to EG4

Edit2: Also, just saying, unless you want this to be a kind of a hobby. I suggest to spend a bit more and get good quality devices that you can extend in future. Even if you have to start with a much smaller system initially. (So essentially opposite of what I do 🤣)
 
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Rednecktek said:
Like who? Links please?
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Here you go.
Rednecktek said:
True enough, I'm just thinking that the technology isn't likely to get that much better and I can afford a couple 6000xp's and a battery every time I come home over the next few years, but trying to buy 6 or 8 plus batteries plus panels plus starlink plus closing costs plus container plus well plus plus plus all at once is much more difficult.

I have to think of it like a personal investment account. If I don't put the money into the account every payday, that money WILL find somewhere else to be. So if I don't buy what I know I'll be able to use as I go along, I won't have the money to do it all at once later. My rough math says I can afford a 6000xp and build a 48v 304Ah battery every 8 months, so I should be able to swing 4x batteries and 4x inverters in stock before I have to worry about the rest of the system.
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Very true, plus it's never a bad idea to have a plan and additional redundancy in today's times.
 
I really like my 18 KPV inverters paired with PowerPro batteries, they are essentially infinitely expandable. I am with the others who think that 200 amp service might be overkill, though if your main panel is rated for 200 A and you only have a couple of 18 KPV inverters to start with, you can always add more inverters and not have to upgrade the electrical service.

They can be noisy though, so think about a separate outbuilding for your power house.
 
I ruled out the 18k's because they only provide 12kw of power and I can get 3 6000xp's for less than a single 18k and get 50% more power out of it. Since the hardware will be indoors and there will never be a grid connection, the 18k just has me paying for features that I'll never use at the cost of usable output.
 
Rednecktek said:
That looks like a really nice option. The thread mentions that SRNE doesn't sell direct anymore, who are the stickers on the front nowadays?
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You can still buy SRNE, they aren't selling small quantities from their storefront. I've used Borick Solar with great success.
If you want relabels SGP and I think Powmr are painting them a different color and marking up the price.
 
Rednecktek said:
Plus if I can figure out what I'll need now I can start buying parts as I get ashore and not have to find all the money up front. I don't figure AIO's are going to make a huge leap in technology for the dollar in that time.
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Even with a 200 amp panel, 100 amp continous is probably more than enough power for a typical house.

If you plan on paralleling inverters, buy them all at the same time. Models change slightly, which may impact the ability to parallel.
 
Rednecktek said:
I ruled out the 18k's because they only provide 12kw of power and I can get 3 6000xp's for less than a single 18k and get 50% more power out of it. Since the hardware will be indoors and there will never be a grid connection, the 18k just has me paying for features that I'll never use at the cost of usable output.
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Three 6000XPs are going to be rather loud indoors if thats anywhere near your living spaces.
 
Rednecktek said:
...

I have to think of it like a personal investment account. If I don't put the money into the account every payday, that money WILL find somewhere else to be. So if I don't buy what I know I'll be able to use as I go along, I won't have the money to do it all at once later. My rough math says I can afford a 6000xp and build a 48v 304Ah battery every 8 months, so I should be able to swing 4x batteries and 4x inverters in stock before I have to worry about the rest of the system.
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I would think that extra money you get should be first invested in the property you want to own. Once you have that the priorities of what is needed to take it from unimproved to livable will alter your plans.

I have done it twice completely in my life to take a totally undeveloped piece of land (1st was a 60 acre parcel in Eastern Washington and second is my 80 acre place here in AR) and overtime building homes on them. Not by hiring others but doing it myself. It has all kinds of unexpected events and expenses. I had to pay to bring grid power to both places. The property in WA. I got some back as new neighbors tied into the power line.

Depending on the land the first thing is clearing it and establishing an access and building site. During this stage a temporary power supply such as a gas generator is what you need.
 
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We're building a new house and a separate barn with living quarters above it, totally off grid, in Maine. After months of research (and having a Victron system in our current property) I went with multiple EG4 6000XPs. They're in the garage of the current house waiting for our contractor to finish some things at the new place before install, but I think your math makes sense.

What I would respectfully suggest you recalculate are your energy needs. While I'll install the largest 200 amp load center I can find (to have many separate circuits), three years of energy monitoring with Emporia Vues at our current property convinced me I probably won't need more than about 50-75 amps in each building, and that's with electric cooking (induction), electric dryer (going to try ventless, but could switch to traditional vented if necessary), hot water heat pump water heater, and even heat pumps for HVAC (air-air for cooling and shoulder seasons, air-water for real winter, using hydronic). We will have propane backing that heat pump up, admittedly, but that doesn't really affect the inverter sizing as much as the solar and battery calculations.

I went over my calculations with Jason at Current Connected, and he agreed they made sense, so I'm starting with three 6000XPs (one more than I really need, frankly). I will install them so that there's space to easily add more if necessary, but hopefully that won't be necessary. Perhaps a similar approach might work for you.
 
Madcodger said:
We're building a new house and a separate barn with living quarters above it, totally off grid, in Maine. After months of research (and having a Victron system in our current property) I went with multiple EG4 6000XPs. They're in the garage of the current house waiting for our contractor to finish some things at the new place before install, but I think your math makes sense.

What I would respectfully suggest you recalculate are your energy needs. While I'll install the largest 200 amp load center I can find (to have many separate circuits), three years of energy monitoring with Emporia Vues at our current property convinced me I probably won't need more than about 50-75 amps in each building, and that's with electric cooking (induction), electric dryer (going to try ventless, but could switch to traditional vented if necessary), hot water heat pump water heater, and even heat pumps for HVAC (air-air for cooling and shoulder seasons, air-water for real winter, using hydronic). We will have propane backing that heat pump up, admittedly, but that doesn't really affect the inverter sizing as much as the solar and battery calculations.

I went over my calculations with Jason at Current Connected, and he agreed they made sense, so I'm starting with three 6000XPs (one more than I really need, frankly). I will install them so that there's space to easily add more if necessary, but hopefully that won't be necessary. Perhaps a similar approach might work for you.
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Nice thing with three is it gives you some redundancy, even if two fail you've still got something producing.
 
Brucey said:
Nice thing with three is it gives you some redundancy, even if two fail you've still got something producing.
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That's basically my strategy. I even considered keeping the third one on a shelf but will go ahead with installing it. If they work out as well as I hope I may buy a fourth and do that. The big worry for us is more about getting both buildings done in 2024. The barn is coming along nicely now but our contractor is so overbooked the house is looking like a 2025 project.
 
Madcodger said:
That's basically my strategy. I even considered keeping the third one on a shelf but will go ahead with installing it. If they work out as well as I hope I may buy a fourth and do that. The big worry for us is more about getting both buildings done in 2024. The barn is coming along nicely now but our contractor is so overbooked the house is looking like a 2025 project.
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Make sure you have a plan for redoing the primary/secondary inverter configurations in case nothing works when one of them blows up. it should be fairly easy to do, but it may be difficult to figure out in the heat of the moment.
 
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