Bought a new house, solar panels are 1000ft away and not attached to the house. Pondering my options

[Blindsay]

Hey all,

Me and my wife recently purchased our first house and it has a solar array that is about 11kw and has its own solaredge inverter and its own utility meter as it is directly grid tied. The power company just credits us what it produces and we apply it to our house.

we are in the process of getting 4x Tesla Powerwall 3s (Our power company has a really good deal on them) and currently during a grid outage we cannot use our solar. I would like to change that. Trying to brainstorm the most cost effective way. Also, our power company does charge is $20/month just to have the second account (even though it is just producing electricity) so over the course of 30yrs that's like $6k in BS fees.

Trenching 1000ft of cable back to the house? Sounds like id need huge cable and trenching 1000ft of it would be terrible? Unless there is some clever solution with like a transformer to raise the voltage a bunch so i can use smaller guage wire and then reduce the voltage before it connects into the powerwalls

I want to add more solar anyways so maybe leave the existing array alone and then add a smaller like 5kw array near the house that would connect into the pw3's

Other clever ideas?

The current solar was installed in 2015 just as an FYI

 

[timselectric]

Unless you want to move the existing array closer, I don't think that it's worth changing anything with it. I would just leave it as is, and build the new system on its own. But if you really want to use it at that distance, I would just run the DC PV back to your location. That would be the least expensive way.

 

[AlaskanNoob]

Unless you want to move the existing array closer, I don't think that it's worth changing anything with it. I would just leave it as is, and build the new system on its own. But if you really want to use it at that distance, I would just run the DC PV back to your location. That would be the least expensive way.

Yeah, high DC voltage shouldn't take a huge wire.

But if you choose to go with running AC power back to your place, you might consider aluminum cable. We run AC power 700 feet to our cabin and went with an aluminum triplex cable, 250/250 and 4/0 and runs at single phase 240V. Since you're a bit further away, you might need something even bigger.

Making a new system and leaving that old system alone seems like a good option.

 

[wpns]

Unless you want to move the existing array closer, I don't think that it's worth changing anything with it. I would just leave it as is, and build the new system on its own. But if you really want to use it at that distance, I would just run the DC PV back to your location. That would be the least expensive way.

I’m with Tim, leave the array where it is and build a new one closer to your house.

 

[TM48]

Or buy new vertical supports from Sinclair (I think) and reinstall the existing arrays near your house. Work yes but a lot cheaper than all new ground mounts and it would just be holes, concrete and disassembly/reassembly. You might be able to pull or dig out the existing verticals and just bore wider holes for the concrete encased supports.

 

[Blindsay]

Unless you want to move the existing array closer, I don't think that it's worth changing anything with it. I would just leave it as is, and build the new system on its own. But if you really want to use it at that distance, I would just run the DC PV back to your location. That would be the least expensive way.

It looks like the tesla powerwall 3 accepts 480V DC max and 15amp per mppt so my system now is 50a @ 240v and If i change it to 480v thats 25a so does that mean id need to do 2 runs? 2x 480V DC runs at like 12.5amp each?

 

[SomethingAppropriate]

Leave it be.... FOR SURE
Its doing its thing.

 

[timselectric]

It looks like the tesla powerwall 3 accepts 480V DC max and 15amp per mppt so my system now is 50a @ 240v and If i change it to 480v thats 25a so does that mean id need to do 2 runs? 2x 480V DC runs at like 12.5amp each?

Maybe, but the math doesn't work exactly like that.
You will need the panel specs and quantity, to determine what you need to run.

 

[Blindsay]

Maybe, but the math doesn't work exactly like that.
You will need the panel specs and quantity, to determine what you need to run.

ah ok, ill have to go look, I know we have 40 panels but I dont know what model they are and I cant quite tell from my existing photos lol




I had thought about putting them in the red area on this map but the wife doesnt like the way they look.... She did mention taking down the trees in the green area so maybe i can put the panels there

 

[AntronX]

1000' reel of 4-4-4-4 aluminum cable is $1240 w. free shipping. Combine 2 x 10 panel strings into one array per pair of cables. You should get 360V 15A per array/cable pair which is maximum current Powerwall 3 MPPT input supports. Voltage drop will be 12V and 3.3% power loss. I'd also run additional #4 or #2 cable for a ground bond.

 

[wpns]

1000' reel of 4-4-4-4 aluminum cable is $1240 w. free shipping. Combine 2 x 10 panel strings into one array per pair of cables. You should get 360V 15A per array/cable pair which is maximum current Powerwall 3 MPPT input supports. Voltage drop will be 12V and 3.3% power loss. I'd also run additional #4 or #2 cable for a ground bond.

Run a spare for expansion.

 

[DIYrich]

If you are going to trench, I would trench DC and move the Solaredge to the Home.
I'm guessing the panels are wired close to 350v at 30a. For a 2.79% voltage drop, that would be 2awg wire for the 1000ft. 1awg is 2.2%, and 1/0 wire is 1.89%.

If you have 2 strings, then you could do two sets of 4awg for 2.28% loss for 350v at 15a.

If you don't want to trench, you can lay RMC on the ground. Maybe on gravel, concrete, pavers, etc. to give it a rigid base. "U" shaped channel so it is not "buried"? Shallow concrete vault with a pressure treated lumber cover (looks like a wood path)?

 

[Mattb4]

Any effort to relocate the panels would involve your electric company since they look to have a buried cable to the present location. I doubt they would agree to doing that. Your easiest and likely least expensive option is to simply put up a new array closer to your home. Complications are going to be local regulations and the wife when it comes to how that can be done.

Unless I am missing something the Tesla powerwalls would not be cost effective over a simple standby generator setup.

 

[EPicTony]

"our power company does charge is $20/month" What is the average credit from exporting back to the grid ??? I'll bet way more than $20.
Let us know !

 

[Blindsay]

Any effort to relocate the panels would involve your electric company since they look to have a buried cable to the present location. I doubt they would agree to doing that. Your easiest and likely least expensive option is to simply put up a new array closer to your home. Complications are going to be local regulations and the wife when it comes to how that can be done.

Unless I am missing something the Tesla powerwalls would not be cost effective over a simple standby generator setup.

I wouldn't need to relocate their service cable, that goal would be to stop service at that second meter so they stop charging me for it. Also as I mentioned we are getting a deal on the powerwalls from our power company

"our power company does charge is $20/month" What is the average credit from exporting back to the grid ??? I'll bet way more than $20.
Let us know !

I am not sure what your point is? Every month that second account which only produces electricity, I get a bill for $20 (plus taxes) just for having the account

 

[PVGeezer]

Depending on where you live and what you're paying per kWh adding a 4 percent or so voltage drop loss is going to cost you half of more of the $20 per month you're paying the POCO now. So I don't think it's going to be economically justifiable to run a cable back to the house.

As for moving the array, depends on how you value your labor. You should be able to DIY a ground mount for under $2k materials cost, considering that you should be able to reuse a lot of what you already have.

Id suggest incorporating the existing array into your expanded system design so you can build it all at once. Reduce the tilt angle to lower your foundation and structure costs while you're at it, you don't need to be at that high a tilt angle if youre net metered.

 

[EPicTony]

I wouldn't need to relocate their service cable, that goal would be to stop service at that second meter so they stop charging me for it. Also as I mentioned we are getting a deal on the powerwalls from our power company

I am not sure what your point is? Every month that second account which only produces electricity, I get a bill for $20 (plus taxes) just for having the account

My point is you are getting more credit from the power company for grid tied than the $20/month. It appears that the solar produces income for you. The question was how much credit are you getting on average per month?

 

[Blindsay]

My point is you are getting more credit from the power company for grid tied than the $20/month. It appears that the solar produces income for you. The question was how much credit are you getting on average per month?

Yeah, but it is still a waste of $6000 over the next 30yrs that im giving to the utility for nothing really. Rather spend it on something more useful (like being able to use my solar during a grid outage). Also they dont let me apply the credit towards that $20/mo so that is a bill i get from them despite having a surplus

I dont have a full year yet but the previous owners produced close to 15mwh for the year and used about 9.5mwh

I know we are going to use more power then them though and eventually id like to add more heat pumps to wean us off of the oil furnace so that means ill need even more electric

 

[EPicTony]

^ Yes, there have been months where I used zero electricity but the bill is still about $30. That's just the way it is. Having the grid as a back up is actually worth $30/month to me. It's a pain to have to haul out generators and such when the grid will power the inverter when necessary.

 

[Blindsay]

^ Yes, there have been months where I used zero electricity but the bill is still about $30. That's just the way it is. Having the grid as a back up is actually worth $30/month to me. It's a pain to have to haul out generators and such when the grid will power the inverter when necessary.

Yeah im just paying that fee 2x right now because I have one account for the house and a second account for the solar.

The bigger issue though is i want to be able to use my solar when we loose the grid, which i cant right now

 

[JWLV]

I think what EPicTony is trying to say is not to think of the $20 grid connection fee as a negative.
You said you are getting 15 megawatt-hours per year from the solar panels. That's 1250 kwh per month on average. Let's assume the national average electricity cost of $0.15 per kwh. That comes to $187/month. Instead of thinking that you are paying a $20 grid connection fee, you should be thinking you're getting $187-$20 off your electrical bill each month. If you don't change anything to your current solar system and you add the powerwall batteries and a second meter, you're still getting $187 - $20 - $20 off your electrical bill each month. That's still a very big positive. If I had this house and property, I'd do this all day long. If I had 10 houses with the same setup, I'd do this 10 times all day long.

There are a lot of assumptions in my opinion above. One is that you use all the power you generate. Two is I did not consider the buy-back price for excess power. Three, your location's electricity price. Etc...

 

[zanydroid]

As for moving the array, depends on how you value your labor. You should be able to DIY a ground mount for under $2k materials cost, considering that you should be able to reuse a lot of what you already have.

If the new mount needs to be done to code, it will cost more than $2K for either pre engineered solution or an engineer stamp on the DIY design

 

[zanydroid]

If moving the inverter, confirm that the Solar Edge signaling to the optimizers is able to go 1000ft

If doing new inverter, the SolarEdge optimizers have to be removed

Are the optimizers compensating for extended hours of tree shading?

 

[AntronX]

The bigger issue though is i want to be able to use my solar when we loose the grid, which i cant right now

In this case all financial arguments against ditching dedicated PV grid connection no longer apply. Spend what it takes to trench and run the cable, treat it as an expense for backup power source.

 

[EPicTony]

In this case all financial arguments against ditching dedicated PV grid connection no longer apply. Spend what it takes to trench and run the cable, treat it as an expense for backup power source.

And lose approximately $187/month??