Solar battery 75' from house

[kc130up]

After reading on here about "multiple" DIY battery fires, I am not comfortable placing my DIY batteries inside (or next to) the house.

I can place my batteries in the shed which is ~75' away from the house.

Based on my favorite voltage drop calculator, 75' at 70a requires 1/0 AWG copper cable for less than a 1.5% voltage drop. 150" of 1/0 copper is ~$900.

Any alternatives, or is my math bad?

 

[1201]

After reading on here about "multiple" DIY battery fires, I am not comfortable placing my DIY batteries inside (or next to) the house.

I can place my batteries in the shed which is ~75' away from the house.

Based on my favorite voltage drop calculator, 75' at 70a requires 1/0 AWG copper cable for less than a 1.5% voltage drop. 150" of 1/0 copper is ~$900.

Any alternatives, or is my math bad?

Your inverter can do 10kw correct? So wouldnt that be 200adc at 51v?

 

[42OhmsPA]

Put the inverter with the batteries and run AC back to the house.

 

[SparkyJJO]

Put the inverter with the batteries and run AC back to the house.

This.

Or not worry so much about LFP. Have the proper fuses/breakers, and build it right, and don't worry about it. Mine are in my basement. My property isn't big enough to put the batteries 75 feet away from the house!

I mean shoot, I am not worried about the natural gas line in my house that feeds my furnace and water heater, even though I know of a house that exploded to due a natural gas leak. Nor do I worry about driving my gasoline car, even though I've seen a car fire on the side of the road (and an EV car fire, for that matter).

 

[42OhmsPA]

My ~54kWh are in my basement/garage too.
They are across from the fuel oil tank next to the gas powered quad and project truck.
My coal stove keeps them warm in the winter.
My EV stays in the other garage away from the house....

 

[x98myers7]

put all your stuff in the shed. put together a very well insulated battery box with an electric blanket under a raised floor the batteries sit on. run the AC back to the house. problem solved.

if I could have a shed on my property, that's what I'd do.

 

[SparkyJJO]

My ~54kWh are in my basement/garage too.
They are across from the fuel oil tank next to the gas powered quad and project truck.
My coal stove keeps them warm in the winter.
My EV stays in the other garage away from the house....

Yeah if I had a large, and potentially moody cobalt battery chemistry I'd keep it far away from my house too!

 

[kc130up]

Your inverter can do 10kw correct? So wouldnt that be 200adc at 51v?

The Tiny EG4-3000 is an fully offgrid system for the shed. Mostly lights, fans, and power to run a freezer. Maybe a mini split later on. It's a decent sized shed/workshop 14x18 or so.

On my house, I am planning a much larger system this summer. 44X 415W panels, a Flexboss21, and a few 16kW DIY batteries.
I hear the "just put the batteries in the basement and don't worry about it", but I'm not going that route. I would rather spend $1800 on copper than put a DIY battery i built with 2% experience in my house.

Putting the inverter in the shed is an idea. I'd have to get all (3) 500VDC solar strings from the house to the shed, then run the AC back to the house. Electrically, smaller DC cables to get the 500VDC to the shed is cheaper and getting 70A back to the house would only require THHN.

Since the house system will be grid tied with net metering, I wonder if I can get a permit to put the inverter int he shed.

 

[1201]

The Tiny EG4-3000 is an fully offgrid system for the shed. Mostly lights, fans, and power to run a freezer. Maybe a mini split later on. It's a decent sized shed/workshop 14x18 or so.

On my house, I am planning a much larger system this summer. 44X 415W panels, a Flexboss21, and a few 16kW DIY batteries.
I hear the "just put the batteries in the basement and don't worry about it", but I'm not going that route. I would rather spend $1800 on copper than put a DIY battery i built with 2% experience in my house.

Putting the inverter in the shed is an idea. I'd have to get all (3) 500VDC solar strings from the house to the shed, then run the AC back to the house. Electrically, smaller DC cables to get the 500VDC to the shed is cheaper and getting 70A back to the house would only require THHN.

Since the house system will be grid tied with net metering, I wonder if I can get a permit to put the inverter int he shed.

This is what I did. I ran my DC to the shed(518voc) , and then ran ac 65 ft from the shed to the subpanel in the house.

The batteries are in the air conditioned shed right next to the inverters so wire lengths are short.

If you haven't bought your inverters, look at the high voltage inverters like the Solis s6. 408vdc batteries makes for some very small wires if you still want to put the inverter in the house and the battery in the shed

 

[yabert]

Continue to learn about those battery and you will then be comfortable to put them near/in the house.
Always the same story: human is fear from unknown.

35 kWh LFP in house.
64 kWh NMC near the house on 4 wheels.

 

[kc130up]

That may be a possibility, but I don't think the wife would ever be on board with that!

15 panels per string at ~38v / 14a per panel is ~ 570v / 14a per series string. The voltage drop for 100 feet at 570v / 14a is less than 1%.

So id need ~600' of 12 AWG PV wires for all 3 strings to make it to the shed. Its 75 on the ground to the garage, but If i have to go 20' in the air, then its a longer wire run.

Then I just need a single AC cable (maybe THHN) to go 75' from the shed back to the panel. This looks to require 1 AWG for 120v 70a.

I am liking this put the inverter & batteries in the shed plan. Thanks for the suggestion!

 

[wpns]

If you put the inverters in the house, make sure you know how much fan noise they are going to make.

 

[kc130up]

Indeed. I read how the fans were "louder" than most people anticipated. My inverter was going in the garage which is far enough away from any sleeping areas not to be an issue.

 

[1201]

That may be a possibility, but I don't think the wife would ever be on board with that!

15 panels per string at ~38v / 14a per panel is ~ 570v / 14a per series string. The voltage drop for 100 feet at 570v / 14a is less than 1%.

So id need ~600' of 12 AWG PV wires for all 3 strings to make it to the shed. Its 75 on the ground to the garage, but If i have to go 20' in the air, then its a longer wire run.

Then I just need a single AC cable (maybe THHN) to go 75' from the shed back to the panel. This looks to require 1 AWG for 120v 70a.

I am liking this put the inverter & batteries in the shed plan. Thanks for the suggestion!

Consider adding a cheap mini split in there to keep everything at a happy temp

 

[SparkyJJO]

Consider adding a cheap mini split in there to keep everything at a happy temp

 

[kc130up]

Of course! Already eyeing the EG4 9K!

 

[1201]

Of course! Already eyeing the EG4 9K!

View attachment 284423

Why not just get a regular 9000 btu unit for about $500, instead of $1600 for the eg4

 

[42OhmsPA]

I hear the "just put the batteries in the basement and don't worry about it", but I'm not going that route. I would rather spend $1800 on copper than put a DIY battery i built with 2% experience in my house.

I did it with 0% experience, 3 years later and 2 expansions; 0 issues.

15 panels per string at ~38v / 14a per panel is ~ 570v / 14a per series string. The voltage drop for 100 feet at 570v / 14a is less than 1%.

These voltages sound way to high for a happy MPPT. Did you do cold weather calculations on VOC?

 

[wheelman55]

Do your math again.

We are off grid. Array is 150 feet from the power shed. The house is 135 feet from the power shed. The power shed houses inverter, charge controller and Lithium batteries. We put a mini split in the shed to keep the electronics and batteries cool.

We ran 10 awg THHN copper from array to shed. This was DC. Maybe 300 volts and 20 amps.

Then we ran AC L1/L2 for 240 volts 135 feet to the house with 4 AWG stranded copper. The house is nice and quiet.

Are you running L1/L2 for 240 volts total? Or just one set of wires for 120 volts?

Once again. Do your math.

 

[J.H.]

Put the inverter with the batteries and run AC back to the house.

That’s what I did 3 years ago ..the ac runs 36 feet through my 6 gauge shore power cord but the inverter , batts and all else is next each other in it’s enclosure… … it works wonderful … run the ac over distance not the dc , if possible….

 

[42OhmsPA]

… run the ac over distance not the dc , if possible….

Unless it's HV DC for PV.

 

[MarkSolar]

...and getting 70A back to the house would only require THHN.

Most THHN is dual rated THWN now, but you can't use THHN in underground conduit so make sure to check the marking on the jacket.
You can price aluminum wire, it's usually about 20% cheaper for the same current carrying capacity.
Also price out XHHW, it's easier to work with and sometimes is cheaper than THWN for reasons I don't understand since it has a better jacket.

 

[J.H.]

Unless it's HV DC for PV.

I was speaking of the ac leaving the inverter.. but I agree.

 

[kc130up]

Do your math again.

We are off grid. Array is 150 feet from the power shed. The house is 135 feet from the power shed. The power shed houses inverter, charge controller and Lithium batteries. We put a mini split in the shed to keep the electronics and batteries cool.

We ran 10 awg THHN copper from array to shed. This was DC. Maybe 300 volts and 20 amps.

Then we ran AC L1/L2 for 240 volts 135 feet to the house with 4 AWG stranded copper. The house is nice and quiet.

Are you running L1/L2 for 240 volts total? Or just one set of wires for 120 volts?

Once again. Do your math.

Absolutely. That was quick back of a napkin math. I will confirm the calculations with my electrician before we install!

 

[kc130up]

Most THHN is dual rated THWN now, but you can't use THHN in underground conduit so make sure to check the marking on the jacket.
You can price aluminum wire, it's usually about 20% cheaper for the same current carrying capacity.
Also price out XHHW, it's easier to work with and sometimes is cheaper than THWN for reasons I don't understand since it has a better jacket.

You are 100% correct. THHN isnt rated for wet locations. I'll need THWN like you said.

I will look into XHHW. From what i read in a few minutes, you would think XHHW was more expensive being PVC vs XLPE.