Suggestions for whole house off-grid system?

[JBoffgrid2022]

So this property is in Maine but you currently have not built?
You are proposing a massive amount of battery and inverter that is absolutely not required, especially if you are willing and able to use propane.
You need to figure out your high electric consumption devices whether they be heating or cooling.

I have not built the house yet, I am still early in the planning stage. I am also looking into appliances that use propane to help reduce my overall electrical needs. I will be oversizing the solar array too because we go several weeks (sometimes months) without steady full sun especially spring, fall, and winter. Basically every month except June, July, & August!

 

[JBoffgrid2022]

Also bare in mind that the racking and wiring etc is going to add considerable more expense.

Not looking forward to that aspect of the expenses...
While you mentioned it, do you have any suggestions on a good "reasonably priced" wiring supplier for providing the long runs of the string wiring? I'm estimating I will need between 300-400 feet minimum.

 

[JBoffgrid2022]

Since you are in the design stage, you should design a super insulated structure that doesn't need so much power to keep it comfortable.

Absolutely! I plan to build a timber frame structure, facing the south. Perhaps a shed style roof to allow good winter sun rays to heat the main area. Again, starting from scratch here. The main reason we are even doing this is because we need to get out of the city...
Where we currently live is getting to cramped, time to buy land and build our house in the woods!! I'm a firm believer that if you put your mind to it, you can do it. We bought 20 acres with a small hunter's camp on the land back when Covid first hit and love the way life is away from the city. I'd move there in a heart beat but I need to stay closer to my work, which is why we are going to sell our house and build new.

 

[G00SE]

You can buy pallets from inxeption for a grand or more less per pallet.
I have 4 batteries the equivalent size of 4 powerpros and spent half what those cost as well.

That’s not to say you’ve picked poor options, just that if needed, one could acquire items more frugally

To add to this, what are your peak power demands? 3-18kpv seems excessive. We are homesteading and our system is designed around a 10kw inverter. We may add another 5kw for the outbuilding but moreso for redundancy than necessity

 

[JBoffgrid2022]

I hear ya. I see some off-grid builds that are so big($$$)! I think I would just buy a small system and put the rest in silver. Early retire would be nice after the financial reset. Then again, panels are going to get very pricey so may just load up on panels and wait.

Lots of folks ask me about going off-grid, some how if you have solar panels you become some expert. My first question for them is if they want a "grid like" experience or more of a "camping like" experience. Second question is "how much money do you want to let go of"

No one wants the "camping type" experience and once you tell them how much it will cost to replicate the grid they never bug me again.

The only reason I'm even considering off grid is because I don't like being at the mercy of the utility companies. Energy costs shouldn't be this expensive considering we have the resource to supply our own power from the sun, wind, and water. Don't want to get on a rant so I'll leave it at that lol

 

[JBoffgrid2022]

To add to this, what are your peak power demands? 3-18kpv seems excessive. We are homesteading and our system is designed around a 10kw inverter. We may add another 5kw for the outbuilding but moreso for redundancy than necessity

I'm started with three KPV's when I did my first calculations but I'm leaning toward two at this point. I will still invest in a large back up battery bank and/or generator but I'm leaning toward a smaller more robust system.

 

[Drunkin Solar]

Not looking forward to that aspect of the expenses...
While you mentioned it, do you have any suggestions on a good "reasonably priced" wiring supplier for providing the long runs of the string wiring? I'm estimating I will need between 300-400 feet minimum.

Check these links:
Temco for solar cable and welding cable for low voltage hookups. Also crimp lugs and other goodies.
The second link for the ULA ground mount system.

TEMCo Industrial LLC

temcoindustrial.com

UNIRAC LARGE ARRAY (ULA) - Unirac

HOME » GROUND MOUNT » UNIRAC LARGE ARRAY (ULA) FLEXIBILITY FOR ANY SIZE PROJECT UNIRAC LARGE ARRAY (ULA) supports a wider range of site and climatic challen ...

unirac.com

 

[JBoffgrid2022]

Check these links:
Temco for solar cable and welding cable for low voltage hookups. Also crimp lugs and other goodies.
The second link for the ULA ground mount system.

TEMCo Industrial LLC

temcoindustrial.com

UNIRAC LARGE ARRAY (ULA) - Unirac

HOME » GROUND MOUNT » UNIRAC LARGE ARRAY (ULA) FLEXIBILITY FOR ANY SIZE PROJECT UNIRAC LARGE ARRAY (ULA) supports a wider range of site and climatic challen ...

unirac.com

I found this solar wire on the site, seems like a good price for 500' of 10 AWG.

10 AWG Solar Panel Wire SW0006 - 500 ft - UL 4703 Power Cable Black - Made in USA

temcoindustrial.com

Or would you recommend 8AWG for the long run?

8 AWG Solar Panel Wire SW0084 - 500 ft - UL 4703 Power Cable Red - Made in USA

temcoindustrial.com

I would need to find out if I could even get MC4 connectors that large.

 

[G00SE]

I'm started with three KPV's when I did my first calculations but I'm leaning toward two at this point. I will still invest in a large back up battery bank and/or generator but I'm leaning toward a smaller more robust system.

2-18kpv would be a nice system! Sounds like you are well on your way.
Best of luck

 

[Drunkin Solar]

I found this solar wire on the site, seems like a good price for 500' of 10 AWG. Or would you recommend 8AWG for the long run?

10 AWG Solar Panel Wire SW0006 - 500 ft - UL 4703 Power Cable Black - Made in USA

temcoindustrial.com

If you have a long run you definitely want to consider 8 gauge. Others on here have links to calculators for voltage drop. You will have losses on a long run no matter what. Higher voltage strings are better (less loss)

They have very competitive pricing. My run is about 125 ft. Strings are at a high of 200 volts. No huge losses running 10 gauge.

 

[Hedges]

Here is a quote I got recently from Sig. Solar. I need to modify the panel types though. I am thinking I will use two different types of panels for the three MPPT inputs.

Three inverters, six batteries.

Do you really need so much peak power? And able to drain battery in 2 or 3 hours.
Try to get by with single inverter, more batteries per inverter for more storage.
Arrange to not run all big loads at once.

I found this solar wire on the site, seems like a good price for 500' of 10 AWG.

10 AWG Solar Panel Wire SW0006 - 500 ft - UL 4703 Power Cable Black - Made in USA

temcoindustrial.com

Or would you recommend 8AWG for the long run?

8 AWG Solar Panel Wire SW0084 - 500 ft - UL 4703 Power Cable Red - Made in USA

temcoindustrial.com

I would need to find out if I could even get MC4 connectors that large.

Long runs don't have to be PV wire. Usually we connect PV wire to an electrical junction box with MC4 pigtails, then use THHN/THWN-2 building wire in conduit. Or could use UF wire which could be direct buried. We often combine multiple strings in parallel, use one larger wire for home run.

Calculate voltage drop vs. gauge. Unlike AC wiring and battery cable, no particular voltage drop percentage matters that much; it is just efficiency loss during times of peak production. That can be offset with more PV panels (but never violate maximum open-circuit voltage limit of inverter/SCC.)

Don't just run two wires (PV+/PV-). Include a ground wire, and tie PV panel frames to inverter chassis. They often present a shock hazard if not bonded to inverter that way, because many inverters superimpose AC on PV wires.

 

[Q-Dog]

I personally think you aren't far enough along on the house design to think about how many inverters or batteries you need to buy.

 

[timselectric]

I personally would be looking at off grid AIO's for an off grid location.
Hybrid AIO's just add expense for unneeded features.

 

[JBoffgrid2022]

Three inverters, six batteries.

Do you really need so much peak power? And able to drain battery is 2 or 3 hours.
Try to get by with single inverter, more batteries per inverter for more storage.
Arrange to not run all big loads at once.



Long runs don't have to be PV wire. Usually we connect PV wire to an electrical junction box with MC4 pigtails, then use THHN/THWN-2 building wire in conduit. Or could use UF wire which could be direct buried. We often combine multiple strings in parallel, use one larger wire for home run.

Calculate voltage drop vs. gauge. Unlike AC wiring and battery cable, no particular voltage drop percentage matters that much; it is just efficiency loss during times of peak production. That can be offset with more PV panels (but never violate maximum open-circuit voltage limit of inverter/SCC.)

Don't just run two wires (PV+/PV-). Include a ground wire, and tie PV panel frames to inverter chassis. They often present a shock hazard if not bonded to inverter that way, because many inverters superimpose AC on PV wires.

I totally get it... No I don't think I'll need that much peak power, but then again I don't want to limit myself too much right off the gate. I realize most systems are expandable but I would hate to go down that road right away once we moved in.

Regarding PV wire choices, 10AWG seems like my best option. I would be running 4 strings per inverter, with two KPV's that would be 8 strings, correct?

I'm a little confused on what you said: "Don't just run two wires". Wouldn't one single ground wire connecting the array to the inverter suffice?

 

[JBoffgrid2022]

I personally would be looking at off grid AIO's for an off grid location.
Hybrid AIO's just add expense for unneeded features.

I'm looking into using 4 EG4 6000XP's in parallel vs 2 KPV's also. Due to the fact that I don't need hybrid, 6K XP's might be a better fit. Plus I already have an extra one from my camp installation that I can use so I would only. need to buy 3.

 

[wpns]

I personally think you aren't far enough along on the house design to think about how many inverters or batteries you need to buy.

This. You need a much better estimate of your actual load and load profile. Can you measure your current power consumption and see how it matches up with your calculations?

 

[JBoffgrid2022]

This. You need a much better estimate of your actual load and load profile. Can you measure your current power consumption and see how it matches up with your calculations?

I have.
Based on consumption of our current house we use 100kw a day on the summer months and only 40kw in the winter. But these figures would be different assuming our new house would be more energy efficient and using a different method of cooling. I would like to see our power consumption closer to 40-50kw daily. If that were the case I think my options for an off grid system would much more affordable!

 

[smr.ruby]

I'm weighing the costs of installing this system vs. paying the utilities company to bring in poles or underground wires. So far, my $40-50k solar costs are a LOT less than our local utility company which came in at close to $90k, plus I would have to pay for the cost of using the power.

Same here, I'm building a house where the default/historic option is to pull a new power line (needs to run about ~1mile) at a cost of about $80K. $80K pays for a lot of solar and batteries. But when you are building new and home values are $800K+ the $50K for solar+battery plus the rest of construction cost will still have me spending less money (being cheap ) than buying an existing house that is grid tied.

 

[smr.ruby]

No one wants the "camping type" experience and once you tell them how much it will cost to replicate the grid they never bug me again.

In the right circumstances I think we're getting close to being able to replicate the grid with less cost than the grid. Grid cost me $80K. $80K in solar and storage would buy something that doesn't look like camping. Sure the overall house has to be efficient and you have to be more conscious of use than a grid connection.... but feeling like we're pretty close to parity. Assuming I install myself that is ... add in somebody else's labor and profession services and it probably breaks.

 

[JBoffgrid2022]

This setup would give me 24kw at the panel, 114kwh of back up power, and plenty of solar input. All for $43,507