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NEWBIE QUESTION: Long run of wire

HPaulPayne

HPaulPayne

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Joined
Jun 8, 2021
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I have 30 400w panels and am building a 48v off-grid system for my house.

My problem, as well as the related questions, revolve around the fact that the house is about 1,000 feet (of buried underground wire) from the location of the panels!

What is the best way to get the power from the panels - to the house?

Should I install the inverters (2 Sol Ark 15k are planned) and large battery bank in the nearby shop? Or, should I run the power from the panels to the house and put the batteries and inverters there?

I have no idea what kind of wire, or sizes, would be required for each option.

Thank you for any input you can provide to me.

Paul
 
Not really practical to run 1000ft unless you use high voltage. One possibility is to setup your solar facility and invert to 240vAC. Then using a 240vAC to 600vAC step up transformer to feed the 1000ft run. At your home you would need a 600vAC to 240vAC step down transformer. Would not be cheap however since these transformers run around $3500 ea.
 
With a 1000’ of distance (2000’ round trip)… that’s a lot!

With distance and amperage you have voltage drop.

So generally you want the voltage drop to be happening on the lowest amperage wires (smallest).

That will usually mean have your panels far away, and the batteries and inverter close. You will also want to increase the voltage to the highest possible (less amperage).

Some other things to consider…
I assume you will need to power both your shop and house. You may want to consider an inverter at the shop for shop stuff and one at the house for house stuff.

The spec sheet I saw says the Pv inputs are 500v. Get your Pv volts close to that (without it ever going over due to the cold temps in your area).

Thicker wire will help reduce voltage drop (but costs more). How are you planning on stringing the wires over the 1000 feet? Direct bury, bury in conduit, or in the air?

Good Luck!
 
Rocketman said:
With a 1000’ of distance (2000’ round trip)… that’s a lot!

With distance and amperage you have voltage drop.

So generally you want the voltage drop to be happening on the lowest amperage wires (smallest).

That will usually mean have your panels far away, and the batteries and inverter close. You will also want to increase the voltage to the highest possible (less amperage).

Some other things to consider…
I assume you will need to power both your shop and house. You may want to consider an inverter at the shop for shop stuff and one at the house for house stuff.

The spec sheet I saw says the Pv inputs are 500v. Get your Pv volts close to that (without it ever going over due to the cold temps in your area).

Thicker wire will help reduce voltage drop (but costs more). How are you planning on stringing the wires over the 1000 feet? Direct bury, bury in conduit, or in the air?

Good Luck!
Click to expand...
Either direct bury or Bury in conduit.

Thanks.

Paul
 
You didn't specify your panel so I'm guessing they're 40V/10A panels or thereabout. With the Sol-Ark 15 it would be difficult to do 30 panels as the most you can do in series with the 40V is 9 so 9s3p would be 27 panels. 10 would be over the voltage limit of the Sol-Ark.

Based on the math if you did 3 strings of 9 and wired them up separately on 8AWG wire each you'd have a 3.37% loss which is almost acceptable. That would be 6,000 ft of 8awg wire which is probably over $4k in wire just by itself...

Sol-Ark actually has a very nice sizing tool that takes all this into account and tells you whether the string combination with temperatures, panels, wire sizes and lengths is a workable system or not.

Solar Panel Sizing 4.7

www.sol-ark.com www.sol-ark.com
 
Rocketman said:
With a 1000’ of distance (2000’ round trip)… that’s a lot!

With distance and amperage you have voltage drop.

So generally you want the voltage drop to be happening on the lowest amperage wires (smallest).

That will usually mean have your panels far away, and the batteries and inverter close. You will also want to increase the voltage to the highest possible (less amperage).

Some other things to consider…
I assume you will need to power both your shop and house. You may want to consider an inverter at the shop for shop stuff and one at the house for house stuff.

The spec sheet I saw says the Pv inputs are 500v. Get your Pv volts close to that (without it ever going over due to the cold temps in your area).

Thicker wire will help reduce voltage drop (but costs more). How are you planning on stringing the wires over the 1000 feet? Direct bury, bury in conduit, or in the air?

Good Luck!
Click to expand...
I'm planning on 3 arrays of 10 ten panels. That will total 4000w at just under 500v.

Thanks

Paul
 
GregTR said:
You didn't specify your panel so I'm guessing they're 40V/10A panels or thereabout. With the Sol-Ark 15 it would be difficult to do 30 panels as the most you can do in series with the 40V is 9 so 9s3p would be 27 panels. 10 would be over the voltage limit of the Sol-Ark.

Based on the math if you did 3 strings of 9 and wired them up separately on 8AWG wire each you'd have a 3.37% loss which is almost acceptable. That would be 6,000 ft of 8awg wire which is probably over $4k in wire just by itself...

Sol-Ark actually has a very nice sizing tool that takes all this into account and tells you whether the string combination with temperatures, panels, wire sizes and lengths is a workable system or not.

Solar Panel Sizing 4.7

www.sol-ark.com www.sol-ark.com
Click to expand...
These are the panels that I have.

I am hoping to use three arrays of 10 each. 4000w / 500v

Thanks

Paul
 

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Is the distance between the shop and the house 50’ or 950’.

If it’s 50’ - you are fine with one set of inverters.

If it’s 950’ - you will want a set of inverters & batteries (and a solar array) for the shop (that will be cheaper than the 3/0 or 4/0 copper cable to run the shop off the inverters at the house or run the house off inverters at the shop).

Also, most electrical wire rolls come in 500 or 1000’ rolls - so you will want to make sure of your measurements before ordering. (975’ is a lot better than 1010’).
 
HPaulPayne said:
These are the panels that I have.

I am hoping to use three arrays of 10 each. 4000w / 500v

Thanks

Paul
Click to expand...
Yeah, as someone above said those panels won't work in 3x10 config with the Sol-Ark unless your temp never drops below 77F. As soon as your temperature drops, Voc climbs and gets past the 500V Sol-Ark limit. If you put the values off of that spec sheet into the Sol-Ark calculator you'll see that too.
 
Some people build solar arrays that would exceed the voltage limit at the array, but after the wire run distance, no longer exceed voltage.

If I remember correctly, midnite's solar calculators are very good at this.

EDIT: "as the temperature drops..." all this storytelling says that a mppt design tool isn't being used, they do all that math for you.

Basically:
- solark doesn't have the product support of a real tier1???
- or it just isn't being used in this case??? (I know midnite's and victron's aren't hard to find)
 
Lilikoi_Heavy_Industries said:
Some people build solar arrays that would exceed the voltage limit at the array, but after the wire run distance, no longer exceed voltage.

If I remember correctly, midnite's solar calculators are very good at this.

EDIT: "as the temperature drops..." all this storytelling says that a mppt design tool isn't being used, they do all that math for you.

Basically:
- solark doesn't have the product support of a real tier1???
- or it just isn't being used in this case??? (I know midnite's and victron's aren't hard to find)
Click to expand...

Sol-Ark does appear to have the support of a real Tier1, I really don't understand why the hate towards them.

I literally linked to their calculator tool a few comments higher that does everything you want it to do, including wire gauge and length setting for each string, number of conductors for each parallel string, panel arrangement on each MPPT and all panel parameters that can be pre-populated from a database or entered manually if your panel is not listed (they encourage you to send the info to them so they can add it to their list).

"as temperature drops" was all we could go on as the OP didn't disclose the cell specs, their location or any additional pertinent information that would have deemed the answer more accurate. Their second response still didn't show the Jinko panel's Temp Coefficients (We can assume it's similar to the JKM405M-72HL-V, so it's around -0.29 %/C for Voc). Even if we gave them the exact minimum temperature the panels and wire length and everything else would have allowed, the same general consensus would have remained.

- 10s3p of 400W panels is not going to work with a Sol-Ark inverter
- 1,000 ft run will produce significant voltage drop even with 8AWG wires.

I could provide the exact numbers as to how much you're overshooting the Voc limit and what percentage of power loss you're facing on the wire run but it wouldn't matter, the final result is the same.

For completeness sake, here is the link again: https://www.sol-ark.com/solar-panel-sizing/SolarPanelSizing.html

And if I put in the panel specs they provided (and assume -0.29%C for Voc coefficet) and try to run 10s3p setup on 1,000ft 8AWG wire I would get 2.89% loss so as soon as the Voc at the panel level would go over 515 V the Voc would go over the 500V limit at the inverter. This would happen at 13C/55F. So if the OP lives in an area where it never gets below 13C/55F then by golly, he can run the 1,000ft run on 3 pairs of 8AWG on the 3x10 system and be within specs.

With the 9s3p setup I suggested on 8AWG they would have 3.21% Voltage loss so they could have that system work all the way down to -27C/-16F, a much better proposition.

Contrary to what you assumed, I did run the numbers I just didn't bother sharing them as they make no difference in the recommendation which is: do not run 3x10 on a Sol-Ark 15K and use 8AWG on your wire if you're that far, full stop.
 
GregTR said:
Sol-Ark does appear to have the support of a real Tier1, I really don't understand why the hate towards them.

I literally linked to their calculator tool a few comments higher that does everything you want it to do, including wire gauge and length setting for each string, number of conductors for each parallel string, panel arrangement on each MPPT and all panel parameters that can be pre-populated from a database or entered manually if your panel is not listed (they encourage you to send the info to them so they can add it to their list).

"as temperature drops" was all we could go on as the OP didn't disclose the cell specs, their location or any additional pertinent information that would have deemed the answer more accurate. Their second response still didn't show the Jinko panel's Temp Coefficients (We can assume it's similar to the JKM405M-72HL-V, so it's around -0.29 %/C for Voc). Even if we gave them the exact minimum temperature the panels and wire length and everything else would have allowed, the same general consensus would have remained.

- 10s3p of 400W panels is not going to work with a Sol-Ark inverter
- 1,000 ft run will produce significant voltage drop even with 8AWG wires.

I could provide the exact numbers as to how much you're overshooting the Voc limit and what percentage of power loss you're facing on the wire run but it wouldn't matter, the final result is the same.

For completeness sake, here is the link again: https://www.sol-ark.com/solar-panel-sizing/SolarPanelSizing.html

And if I put in the panel specs they provided (and assume -0.29%C for Voc coefficet) and try to run 10s3p setup on 1,000ft 8AWG wire I would get 2.89% loss so as soon as the Voc at the panel level would go over 515 V the Voc would go over the 500V limit at the inverter. This would happen at 13C/55F. So if the OP lives in an area where it never gets below 13C/55F then by golly, he can run the 1,000ft run on 3 pairs of 8AWG on the 3x10 system and be within specs.

With the 9s3p setup I suggested on 8AWG they would have 3.21% Voltage loss so they could have that system work all the way down to -27C/-16F, a much better proposition.

Contrary to what you assumed, I did run the numbers I just didn't bother sharing them as they make no difference in the recommendation which is: do not run 3x10 on a Sol-Ark 15K and use 8AWG on your wire if you're that far, full stop.
Click to expand...
Yep 3 pairs sounds about right.

I have no use for an inverter that burns up so much power just to be turned on.
 
Lilikoi_Heavy_Industries said:
Yep 3 pairs sounds about right.

I have no use for an inverter that burns up so much power just to be turned on.
Click to expand...
OP seems pretty set on Sol-Ark so what you prefer or not on an inverter's own base consumption is immaterial in the discussion other than incessant jabbing at others which does not come across as being friendly or providing legitimate advice...
 
Lilikoi_Heavy_Industries said:
Some people build solar arrays that would exceed the voltage limit at the array, but after the wire run distance, no longer exceed voltage.

If I remember correctly, midnite's solar calculators are very good at this.

EDIT: "as the temperature drops..." all this storytelling says that a mppt design tool isn't being used, they do all that math for you.

Basically:
- solark doesn't have the product support of a real tier1???
- or it just isn't being used in this case??? (I know midnite's and victron's aren't hard to find)
Click to expand...
Voc only happens when there is no current flowing, which means no voltage drop.
 
GregTR said:
OP seems pretty set on Sol-Ark so what you prefer or not on an inverter's own base consumption is immaterial in the discussion other than incessant jabbing at others which does not come across as being friendly or providing legitimate advice...
Click to expand...
There are a lot of people that buy into solark before they realize how much it's going to burn just to be turned on.
 
Use microwave oven transformers.

Warpspeed said:
I saw a thread a long time ago about some guy that used a pair of microwave oven transformers with the shunt gap removed.
He ran a single steel wire on high wooden poles at around 1.5 to 2Kv ac with earth return.
It was only a low power system, but for simplicity and low cost it would be hard to beat.
Very easy to fix too if the wire ever came down.
Click to expand...
On this thread,
diysolarforum.com

Efficient long distance transmission of power

I have 3 separate systems here off grid. I have a situation where I am setting up a solar only system near our cabin and want to run supplemental power in winter (when we only have rain...) to charge this system from a hydro based system about 800' away. I have a 10AWG UF wire run from the...
diysolarforum.com diysolarforum.com
 
Last edited:
I can never think of anything first. My search microwave oven HV transmission lead me to above post link back here !!!
 
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