Reliable Off-Grid Packages

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Ravenvalor

Ravenvalor

Senior Member
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Piedmont region of NC
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres and Duke wants a small fortune to run power to it. I thought that I would do at least a cost feasibility study for an off-grid roof-top (no-shade, full sun) system for her. I was wondering, what's the best affordable off-grid inverter and storage package on the market these days?

Thanks for the help.
 
Ravenvalor said:
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres and Duke wants a small fortune to run power to it. I thought that I would do at least a cost feasibility study for an off-grid roof-top (no-shade, full sun) system for her. I was wondering, what's the best affordable off-grid inverter and storage package on the market these days?

Thanks for the help.
Click to expand...
There are no one size fits all off grid solar packages. You must start with a detailed load analysis and work backwards from there to determine first the required battery capacity and then the size PV system needed to keep it charged. Your customer really should consider including a generator as well to provide power when your best predictions fall short.

Designing and maintaining off grid energy systems is a whole lot more complex than grid tied PV systems. My advice to you is not to take this on if you don't thoroughly this stuff, and even if you do but your customer doesn't, then expect service calls in perpetuity. We used to do off grid systems occasionally but we don't any more; they are not worth the headaches.
 
Ravenvalor said:
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres and Duke wants a small fortune to run power to it. I thought that I would do at least a cost feasibility study for an off-grid roof-top (no-shade, full sun) system for her. I was wondering, what's the best affordable off-grid inverter and storage package on the market these days?

Thanks for the help.
Click to expand...

Many options. I suggest you lookup "engineer775" on youtube to get some ideas. He's has done many off-grid systems in your neck of the woods.
 
Sol Ark inverters seem to be the latest and greatest on this. They have high power ratings, e.g 15kW continuous and double that for 100ms. Pair them with your favorite batteries. Battery and PV sizing is where it gets more complicated of course. No personal experience with them yet though.
 
analog8484 said:
Many options. I suggest you lookup "engineer775" on youtube to get some ideas. He's has done many off-grid systems in your neck of the woods.
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Probably at least 5 years ago I watched some of his videos. Might have been longer than that now that I think about it. I have to say I was completely under impressed. But your mileage might vary.
 
Never done or dealt with medium voltage, But the user “Electronfelon” uses and discussed his set up medium voltage.
Could run that your self and have reliable power then use solar as back up.
Have no idea on cost comparison. But if it’s my home and not just a camping shack I would not like to only have solar.
Just my newbie opinion
 
Ravenvalor said:
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres and Duke wants a small fortune to run power to it. I thought that I would do at least a cost feasibility study for an off-grid roof-top (no-shade, full sun) system for her. I was wondering, what's the best affordable off-grid inverter and storage package on the market these days?

Thanks for the help.
Click to expand...
Show her this picture and the cost for running power to her off grid shed may look a lot more appealing.

1660233629548.png
 
petersonra said:
So they have determined inadequate ventilation was the cause?
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I'm not aware of any determination--but if it's a hydrogen explosion (as seems obvious given the lead acid batteries and the damage shown in the picture), then obviously the ventilation was inadequate for the particular conditions that arose. I don't know what the ventilation rules are and whether they are designed to provide sufficient ventilation for all possible hydrogen evolution rates.

Cheers, Wayne
 
IMHO: don't throw emotional FUD into this. Let's help Ravenvalor do the off grid study.

My _guess_ is that once the off grid study is complete the customer will realize that doing power in a rural site far from the grid is simply very expensive.

Solar kWh are cheap and getting cheaper, but only if you use those kWh when the sun is shining. Energy storage is expensive. So part of any off grid design is to design the loads to better match available sunlight.

Also consider than better insulation and efficiency and reducing energy consumption must be a large part of such a design.

Finally a huge energy user in a home is heating. This is often better done burning fuel rather than with electricity. (But see the point about energy storage; you can store heat such as in a well insulated hot water tank, or simply warming up a well insulated house. So if you run heat pumps when the sun is shining that is itself a way of matching loads to solar production.)

-Jon
 
wwhitney said:
I'm not aware of any determination--but if it's a hydrogen explosion (as seems obvious given the lead acid batteries and the damage shown in the picture), then obviously the ventilation was inadequate for the particular conditions that arose. I don't know what the ventilation rules are and whether they are designed to provide sufficient ventilation for all possible hydrogen evolution rates.

Cheers, Wayne
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Objection, assumes facts not in evidence. We don't know they were lead-acid batteries. They have several chemistries available.
 
Ravenvalor said:
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres and Duke wants a small fortune to run power to it. I thought that I would do at least a cost feasibility study for an off-grid roof-top (no-shade, full sun) system for her. I was wondering, what's the best affordable off-grid inverter and storage package on the market these days?

Thanks for the help.
Click to expand...
With an 800 sq-ft footprint, I'm doubtful you can get enough power to keep the batteries charged for a 5 day sun drought. If they have 17 acres, why not a ground mount system? You can make it plenty large, easier to maintain, and you can probably stick the batteries in a shed structure under the array.
 
Ravenvalor said:
Hello,

I have a customer who is building an 800 sq/ft home on 17 acres
Click to expand...
We have a few customers off grid with small homes like that, even large homes. Most use outback solar or sunny island systems.
One thing to keep in mind is you can run different systems. Most people do fine with propane for cooking, wood or propane heat and solar with a generator.
The other thing to keep in mind is don't get them a 'backup' generator, rather look for one that is a 'prime' generator. Diesel and propane store better than gas.
Also don't skimp on the tank one place I work on has a buried 1000 gallon propane tank.
If their doing any water pumping (like irrigation) for the 17 acres look into 120V DC systems
 
gadfly56 said:
Objection, assumes facts not in evidence. We don't know they were lead-acid batteries. They have several chemistries available.
Click to expand...
Did you miss this post from jaggedben? They were lead-acid.

"EXPLOSION ROCKS RIO DELL" - Battery storage in Conex box

One mode of failure in some lithium cells that are kept constantly at it near 100% charge is the formation of lithium metal dendrites extending from the lithium electrode. These can pierce the separator between electrodes and short out the cell. Sent from my Pixel 4a using Tapatalk
forums.mikeholt.com

Cheers, Wayne
 
wwhitney said:
I'm not aware of any determination--but if it's a hydrogen explosion (as seems obvious given the lead acid batteries and the damage shown in the picture), then obviously the ventilation was inadequate for the particular conditions that arose. I don't know what the ventilation rules are and whether they are designed to provide sufficient ventilation for all possible hydrogen evolution rates.

Cheers, Wayne
Click to expand...
Seems to me if loss of ventilation is a problem for this kind of system that not accounting for that in the design of the system is a huge design flaw. If that's what happened, one would hope that the legal system would deal with the company harshly for such a gross design defect.
 
wwhitney said:
Did you miss this post from jaggedben? They were lead-acid.

"EXPLOSION ROCKS RIO DELL" - Battery storage in Conex box

One mode of failure in some lithium cells that are kept constantly at it near 100% charge is the formation of lithium metal dendrites extending from the lithium electrode. These can pierce the separator between electrodes and short out the cell. Sent from my Pixel 4a using Tapatalk
forums.mikeholt.com

Cheers, Wayne
Click to expand...
Yes, yes I did. Thanks for the catchup.
 
gadfly56 said:
With an 800 sq-ft footprint, I'm doubtful you can get enough power to keep the batteries charged for a 5 day sun drought. If they have 17 acres, why not a ground mount system? You can make it plenty large, easier to maintain, and you can probably stick the batteries in a shed structure under the array.
Click to expand...

I agree on this point. 800 sq-ft is small, which bodes well for total energy consumption. But it doesn't give you much roof area to work with.

A similar approach to consider is a 'solar pergola' to mount the PV array and provide a useful shade structure for outdoor activities.

-Jon
 
There is very little in common between grid-tied PV system design and off-grid design. There is a lot that someone without experience can get wrong and those errors all end up with the homeowner sitting in a dark house with no power and an expensive bill to fix. That said, it is often cheaper to put in an off-grid system than to pay the utility to run the power line, but not always that much more affordable. So I recommend you find an experienced off-grid system contractor to quote the system.
A solid off-grid residential system that provides a "normal" on-grid experience is quite expensive. A hair shirt cabin in the woods system that is used for a weekend here and there can be pretty inexpensive.
 
One of the big mistakes people make when weighing on vs off grid costs is just making a simple immediate cost comparison. They might think for example, " getting grid power here will cost $50,000, but I can put in an off grid system for $25,000, that's $25,000 cheaper for off grid - no brainer.". But a careful analysis of convenience (forever), battery replacement every 10 years, generator fuel, worry and stress about energy reserves in the winter (forever), increased overall property value.....can paint a much different story.

Remember too that off grid will typically entail specialized expensive appliances that often are excluded from the "system" cost.

Sometimes a step up step down scheme can be much cheaper than a utility line extension.
 
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