AIO vs. Pre-Wired System: Selection and Design help for my little off grid cabin

[Hopitrout]

Looking for Solar Help: 1) Pre-wired vs. AIO system, Manufacturer, etc., 2) then preparing an Electrical One-Line Diagram.

My situation:

Location, East Idaho, 6300ft elevation, just west of Yellowstone National Park. Purchased and moved the 612 ft2 cabin to my property in late 2018, saving it from being torn down to make way for a new hotel. Been restoring it ever since. Never want it to be a house, just a beautiful “glamping +” set up. I built and permitted an outhouse and installed a shallow sand point well which I pump with a 1926 era piston pump a friend and I rebuilt.

Access by road is limited to 6 months/year due to huge snow. -40F outside temps every couple of years, coldest recorded -60F. Electronics and battery will be located in uninsulated but full height basement.

An elevated, ground mounted solar panel array will be located 115ft south of the power panel in the basement to avoid ALL shade created by scattered lodgepole pines.

No power to property, completely off grid. Once I have solar power I can get internet.

I have to get my system design approved by the Idaho Department of Building Safety with components tested and approved to the UL-1741 standards, etc. This will include an Electrical One-Line Diagram – To verify compliance with the 2017 National Electrical Code (hand drawn OK).

https://dbs.idaho.gov/programs/elec...e-owners-installing-power-production-systems/

Though I have little electrical experience, I do have some competent friends and with the help of one, we wired my cabin last fall (120VAC) and passed my State Inspection the first time.

The plan:

48V System.

I have access to new 390W Canadian Solar BiHiKu Poly Perc, Bifacials locally ($205/each).

https://signaturesolar.com/content/documents/CANADIANSOLAR/CS3Wspec.pdf

I did an energy needs calc. 4 of the bifacials noted above will be more than ample for my current/future needs (1560 W).

I’m interested in an AIO or Pre-wired system for ease of installation and ease of passing my state inspection.

All in Ones (AIO) Systems:

EG4 6.5kW Off-Grid Inverter, $1,299

https://signaturesolar.com/eg4-6-5k-off-grid-inverter-6500ex-48/

Sol-Ark 5K, $4,500

https://www.sol-ark.com/wp-content/uploads/2021/10/5KSpecSheet_10-4-2021.pdf

Pre-wired Systems:

OutBack Power FLEXpower ONE FXR: VFXR3648A, 3.6kW, $4,100

https://www.outbackpower.com/downlo...expower_one_fxr/flexpoweronefxr_datasheet.pdf

• UL-1741 compliant
• cost
• reliability
• ease of operation (programming and understanding outputs)
• low idle power consumption
• low temp operation
• ability to communicate wirelessly
• availability.

For batteries I’m looking at a lithium or AGM type system with the following very modest capacity:

Nominal Capacity: 100Ah
Kilowatt-hour(s): 5.12kWh

I will do what I need to do for an insulated and possibly heated battery box.

My goal with this post would be to 1) determine which AIO or Pre-wired system and battery(s) to purchase, and 2) once the system is selected, get help on the preparing the Electrical One-Line Diagram so I can submit to the State.

THANKS so much for your help and guidance.

PS, why doesn’t this forum have a section on pre-wired systems?

 

[12VoltInstalls]

For batteries I’m looking at a lithium or AGM type system with the following very modest capacity:

Accommodate for low temperature cutoff and use lithium, or flooded lead acid. AGM will underserve you. Imho

 

[ChrisG]

Don’t use lithium. I have a cabin in a high elevation also ~5000 ft with uninsulated basement and did a test over this past winter with a small LifePO4 setup. We only get down to -20 here luckily. From November to March the average temp in the basement where test batteries and inverter was stayed around 19°F. The amount of energy storage required to keep the batteries warm would be astronomical from an ESS perspective.

I had a small Growatt connected to grid with no panels for this test with a 5kwh 48v pack in a good insulated cooler. Only purpose of the GW was to keep the batteries above 45°F via various warming mechanisms so they could charge if needed. Rough numbers came to about 22kWh/month to keep them at 45°. Assume snow covered panels for a month, that’s an extra $6000 in EG4 batteries just to accommodate LifePO4.

 

[Hopitrout]

AGM will underserve you

12VoltInatalls, just curious, why did you say that AGM will underserve?

 

[Bluedog225]

Sounds awesome. May be a good candidate for some of those panels to be mounted vertically.

 

[Horsefly]

Don’t use lithium. I have a cabin in a high elevation also ~5000 ft with uninsulated basement and did a test over this past winter with a small LifePO4 setup. We only get down to -20 here luckily. From November to March the average temp in the basement where test batteries and inverter was stayed around 19°F. The amount of energy storage required to keep the batteries warm would be astronomical from an ESS perspective.

I disagree. I built and tested an insulated box four out LiFePO4 battery that is now in our cabin at 9,000 ft elevation in Colorado. The entire thread describing the build is here, but you can skip to seeing some of the testing graphs. Bottom line was that I am able to keep the batteries between 50°F and 60°F (10°C and 15°C) with generally about 4Ah per day with temps outside well below freezing. We are keeping the solar on all winter, and even if snow is covering the panels for a couple of weeks at a time, the battery should normally stay pretty well charged.

 

[corporate.joe]

Don’t use lithium. I have a cabin in a high elevation also ~5000 ft with uninsulated basement and did a test over this past winter with a small LifePO4 setup. We only get down to -20 here luckily. From November to March the average temp in the basement where test batteries and inverter was stayed around 19°F. The amount of energy storage required to keep the batteries warm would be astronomical from an ESS perspective.

I had a small Growatt connected to grid with no panels for this test with a 5kwh 48v pack in a good insulated cooler. Only purpose of the GW was to keep the batteries above 45°F via various warming mechanisms so they could charge if needed. Rough numbers came to about 22kWh/month to keep them at 45°. Assume snow covered panels for a month, that’s an extra $6000 in EG4 batteries just to accommodate LifePO4.

22kWh/month comes out as roughly 30 watt constant draw. 700 Watt hours a day. That doesn't seem excessive to me. By the way. I can't remember the reading from my kill-a-watt, but I'm pretty sure that the Growatt AIO's draw several watt's(maybe half of your monthly reading) in pass-through mode.

 

[Hopitrout]

Sounds awesome. May be a good candidate for some of those panels to be mounted vertically.

Bluedog225, absolutely. My panel’s elevated ground mount will have a very steep winter adjustment angle so I assume I’ll rarely if ever have any significant snow accumulation on the panels.

 

[Hopitrout]

I disagree. I built and tested an insulated box four out LiFePO4 battery that is now in our cabin at 9,000 ft elevation in Colorado. The entire thread describing the build is here, but you can skip to seeing some of the testing graphs. Bottom line was that I am able to keep the batteries between 50°F and 60°F (10°C and 15°C) with generally about 4Ah per day with temps outside well below freezing. We are keeping the solar on all winter, and even if snow is covering the panels for a couple of weeks at a time, the battery should normally stay pretty well charged.

Thanks Horsefly. Your thread “On Keeping LFP Warm” was very helpful to me last year as it gave some clarity to expected basement temps in cold environments.

 

[Bluedog225]

Horsefly’s box is over-the-top nice.

Me, I’d dig a hole in the basement and put in a couple of nesting styrofoam coolers. Stack foam sheets on top. One of which has an aluminum side with 3/4 space facing the heated area. The very top layer, flush with the floor would be 3/4 ply as a floor.

edit-or one big cooler and fill the spaces with cellulose.

 

[Hopitrout]

And the main focus: AIO vs Pre-wired component system and then which ones for a 48V system???

 

[ChrisG]

I disagree. I built and tested an insulated box four out LiFePO4 battery that is now in our cabin at 9,000 ft elevation in Colorado. The entire thread describing the build is here, but you can skip to seeing some of the testing graphs. Bottom line was that I am able to keep the batteries between 50°F and 60°F (10°C and 15°C) with generally about 4Ah per day with temps outside well below freezing. We are keeping the solar on all winter, and even if snow is covering the panels for a couple of weeks at a time, the battery should normally stay pretty well charged.

Mine was not nearly the solution you have. I wanted a baseline of what to expect in this climate and it kinda sucked. And to the other individual that posted about draw from Growatt it is a GW 3000SPF, you are correct, the grid usage included any amount needed to keep the system running to maintain the batteries at 90% SOC and heating batteries

My basement is built into a mountain side so only half of the basement is underground, unfortunately not the half where the utilities are where the GW and batters are placed. Only uninsulated cinderblock basement walls exposed floor to ceiling in that area.

 

[12VoltInstalls]

12VoltInatalls, just curious, why did you say that AGM will underserve?

AGM is expensive for a relatively short lifespan and they don’t like deep cycling much. You can get a couple more years out of flooded lead acid usually.

And the main focus: AIO vs Pre-wired component system and then which ones for a 48V system???

Prewired is a weird thing for my head to grasp. Components aren’t pre- anything.

For my opinion: an Epever SCC uses virtually no power, and stand-alone inverters can be low consumption plus you can turn off your inverter.
An MPPSolar AIO can be moderately low consumption depending on model and one’s mindset.

 

[Hopitrout]

AGM is expensive for a relatively short lifespan and they don’t like deep cycling much. You can get a couple more years out of flooded lead acid usually.

Prewired is a weird thing for my head to grasp. Components aren’t pre- anything.

For my opinion: an Epever SCC uses virtually no power, and stand-alone inverters can be low consumption plus you can turn off your inverter.
An MPPSolar AIO can be moderately low consumption depending on model and one’s mindset.

Thanks 12VoltInstalls for the battery advice. For the prewired, see the picture below: individual components can be replaced and these are typically UL-1741 compliant (tested and certified to the standard) as I understand it. I believe they also typically use less standby power than the AIO units. Advice on the best unit(s) and why for my situation is what I was most hoping for from this post.

 

[12VoltInstalls]

What does that cost?!
It’s filled with Outback stuff ?

 

[Hopitrout]

What does that cost?!
It’s filled with Outback stuff ?

Not cheap but I think it would get me where I need to be….
OutBack Power FLEXpower ONE FXR: VFXR3648A, 3.6kW, $4,100
https://www.outbackpower.com/downlo...expower_one_fxr/flexpoweronefxr_datasheet.pdf

 

[400bird]

And the main focus: AIO vs Pre-wired component system and then which ones for a 48V system???

I'd recommend individual components. Pre-wired seems like some wasted expense, but that's your preference. Pre-wired is individual components.
When you leave for the winter (do you leave for the winter?) You can turn off the inverter and leave the SCC on to keep the batteries charged and the battery heater working.
Plus, you should have lower idle consumption going with Outback stuff, but I haven't checked the specs.
Depending on the Outback model, you might get a low frequency inverter that would allow starting motors like a well pump, etc.

What does that cost?!
It’s filled with Outback stuff ?

It's in the first post in this thread.

 

[Hopitrout]

When you leave for the winter (do you leave for the winter?) You can turn off the inverter and leave the SCC on to keep the batteries charged and the battery heater working.

Yes, it’s really not habitable in the winter, not even for a night. We snowmobile in to check on it, but that’s typically it.

 

[Bluedog225]

The pre-wired stuff has some real appeal to someone like me who dabbles in electric stuff but isn’t anywhere near qualified to be considered competent or safe. Throw a little extra money at it and get tier 1 components correctly put together by someone who has built dozens (hundreds?) of systems.

Other than the cost, I don’t see a downside. And as far as I can tell, these guys will pre-wire whatever you want.

Don’t like Magnum? No problem. Want Midnite? No problem.

No fuss, no magic smoke. Seems like a nice midpoint between all in one and components.

Probably better/closer to UL listed than others.

 

[400bird]

Other than the cost, I don’t see a downside.

Yeah, basically this. Your other points are really good too, but this one sums my thoughts up nicely.

Yes, it’s really not habitable in the winter, not even for a night. We snowmobile in to check on it, but that’s typically it.

Yeah, given that info, I'd go with a dedicated components. You can show up at the place, kick on the AC inverter and should be good to go.

With an all in one, my concern would be the idle consumption would kill the battery in the off season between visits. You'd show up on site and have a dead batt.

It's also worth pointing out that with discreet components you can repair, replace, upgrade components individually and not be forced to take the entire thing out for commission for a failure.