Running wires over distance

[Buckworth]

Hello,

I currently have a 12v setup that includes 4 100w panels, 3 105ah deep cycle marine batteries, a 30amp charge controller and a 1000w inverter.

It's set up close to my house to shorten the length needed for wiring and so I can have convenient access to switch the inverter on and off.

My issue is the panels are shaded for at least 25% of the day.

I have an open field about 100m away from my house, and I would love to move the array out there I realize this will create issues with voltage drop. As I understand it, it is better to run AC over distance than DC...so this means I would have to move my inverter with my array.

My question is would the remotes for the inverter and charge controller function over that distance? And if not..are there other solutions?

 

[RCinFLA]

You did not say anything about panel voltage or if you are using an MPPT controller that could take a higher voltage. For longer distance like to use higher voltage with MPPT controller to minimize loss both power and financial loss in copper cost.

A 100 meter run (two wires) would have following resistance.

#6 gauge = 0.264 ohms
#8 gauge = 0.420 ohms
#10 gauge = 0.668 ohms

I would try to put the four panels in series. Just in wire cost for larger gauge you can likely pay for a new higher voltage MPPT controller instead.

 

[Buckworth]

You did not say anything about panel voltage or if you are using an MPPT controller that could take a higher voltage. For longer distance like to use higher voltage with MPPT controller to minimize loss both power and financial loss in copper cost.

A 100 meter run (two wires) would have following resistance.

#6 gauge = 0.264 ohms
#8 gauge = 0.420 ohms
#10 gauge = 0.668 ohms

Thank you for your reply.

I'm not this advanced. Should I have posted in another section?

My understanding is my panels are 100w and feed no more than about 19v to my MPPT charge controller.

I think your scenario is saying I should keep the charge controller/inverter at my house and run the wire carrying max 19v from the panels over 100m? My understanding is it would more efficient to invert at the collection point and run the 120v over the distance.

 

[Supervstech]

Distance reduces the voltage over distance.
Ac or dc.
It is the voltage and amps AND WIRE SIZE that matters.
19v will lose .7v over 100M (WITH 4/0 WIRE)
120v will lose .7V over 100M (WITH#10 WIRE)

 

[Forbisher]

My understanding is my panels are 100w and feed no more than about 19v to my MPPT charge controller.

100 watt panels are about 22 Volts open circuit.
If you series connect those 4 100 watt panels you have about 86 Volts open circuit and 72 volts max production.
Most SCC can accept 86 volts.
Calculate the voltage drop for wire size over 300 feet.

 

[Forbisher]

6 AWG over 300' at 72 Vmp 6A is 1.99% voltage drop
Click on the calculator below to change any of the values.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[Buckworth]

Distance reduces the voltage over distance.
Ac or dc.
It is the voltage and amps AND WIRE SIZE that matters.
19v will lose .7v over 100M (WITH 4/0 WIRE)
120v will lose .7V over 100M (WITH#10 WIRE)

Thank you very much. So if I'm reading that correctly I want run AC at 120v if I want the wire to be cheaper?

 

[RCinFLA]

Thank you for your reply.

I'm not this advanced. Should I have posted in another section?

My understanding is my panels are 100w and feed no more than about 19v to my MPPT charge controller.

I think your scenario is saying I should keep the charge controller/inverter at my house and run the wire carrying max 19v from the panels over 100m? My understanding is it would more efficient to invert at the collection point and run the 120v over the distance.

Based on your statement on panels you probably have 18v panels wired in parallel and likely a PWM controller.

If you can look up your PV panel and PV charge controller info and tell us what you have that would help us steer you in a direction.

If you do not have specs take picture of any labels on them.

 

[Buckworth]

100 watt panels are about 22 Volts open circuit.
If you series connect those 4 100 watt panels you have about 86 Volts open circuit and 72 volts max production.
Most SCC can accept 86 volts.
Calculate the voltage drop for wire size over 300 feet.

Thank you very much. They are currently wired in paralell to an EPEver Tracer 30a charge controller. If i wire them in series is it better because the voltage is higher?...or is it the same? I am limited by either volts or amps.

 

[Forbisher]

Thank you very much. They are currently wired in paralell to an EPEver Tracer 30a charge controller. If i wire them in series is it better because the voltage is higher?...or is it the same? I am limited by either volts or amps.

Yes connect all 4 panels in series which adds the voltage with the amps staying the same as one panel.
Look at my calculator post.
4 100 watt in series are about 86 Voc and 72 Vmp
30 amps x 13 volts is 390 watts.
Why would you want your SCC and inverter 300 feet from your house?
Just run 300 feet 6 AWG cable from the panels.

 

[Buckworth]

Based on your statement on panels you probably have 18v panels wired in parallel and likely a PWM controller.

If you can look up your PV panel and PV charge controller info and tell us what you have that would help us steer you in a direction.

If you do not have specs take picture of any labels on them.

I have an EPEver tracer 30a MPPT charge controller. What I'm picking up is that I should simply run the wire from the panels the 300 feet to my shack and leave the charge controller and inverter where they are. I will experience a <2% drop in voltage, but an major increase in total sunlight.

 

[RCinFLA]

That controller should be able to handle four 18v panels in series. Each panel is likely in 7-8 amp range max.

In parallel that would be about 14v at 30 amps max.

In series that is about 56v at 7-8 amps.

It is a lot easier to send 7-8 amps 100 meters then 30 amps.

Going back to the resistances for 100 meters, #8, with 0.42 ohms is 3.4 vdc drop at 8 amps or 27 watt loss.
#6, at 0.264 ohms would be 8A x .264 ohms = 2.1 vdc drop with 16.9 watts loss.

Just have to make sure the max panel voltage Voc x 4 does not exceed 90v on that controller.

 

[Forbisher]

That controller should be able to handle four 18v panels in series. Each panel is likely in 7-8 amp range max.

100 watt panels are 5.5 to 6amps.
18Vmp x 5.5A is 99 watts!

6 AWG over 300' at 72 Vmp 6A is 1.99% voltage drop
Click on the calculator below to change any of the values.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[PHoganDive]

For longer distance runs, you want to maximize the voltage to minimize the current (and the resistance losses in the wire)...within the voltage limits of the charge controller.
This same thing applies to the power company, thats why you always see very high voltage lines for cross country power wires, they crank the voltage up to hundreds of thousands of volts to minimize the current, and even neighborhood high voltage distribution is 10-20 thousand volts at the top of the phone poles.

 

[Fred S]

Also, assuming you have to bury the new wire, you may want to consider future array expansion. Installing a heavier gauge wire to accomodate more panels may not have very much incremental cost. You could use the calculator that MBR posted to compare the recommended gauge wire for (as an example) 8 amps versus 16 amps, and check the difference in wire cost.

 

[Buckworth]

Also, assuming you have to bury the new wire, you may want to consider future array expansion. Installing a heavier gauge wire to accomodate more panels may not have very much incremental cost. You could use the calculator that MBR posted to compare the recommended gauge wire for (as an example) 8 amps versus 16 amps, and check the difference in wire cost.

OK. So I'm on board with what I need...now my issue is shopping for wire in Canada. The internet is not very helpful shopping for say, 8 awg outdoor wire.

 

[heirloom hamlet]

You did not say anything about panel voltage or if you are using an MPPT controller that could take a higher voltage. For longer distance like to use higher voltage with MPPT controller to minimize loss both power and financial loss in copper cost.

A 100 meter run (two wires) would have following resistance.

#6 gauge = 0.264 ohms
#8 gauge = 0.420 ohms
#10 gauge = 0.668 ohms

I would try to put the four panels in series. Just in wire cost for larger gauge you can likely pay for a new higher voltage MPPT controller instead.

OK. So I'm on board with what I need...now my issue is shopping for wire in Canada. The internet is not very helpful shopping for say, 8 awg outdoor wire.

I have been using my 24v MPPT to power my job site (approx 150') and have not had any real issues. I had my 250w, 37.6v, 8.27a panels in 3S3P (2250w, 113v, 25a).
The manual gave an example setup as 2S4P and I thought that would work better for me in my layout so I made the adjustment.

Well my Festool vac/track saw cuts have been puking out halfway through a cut lately and I am trying to trouble shoot. Now I'm only using 14awg extension cords to get it there and I do also have a.42a fan on, but that was the situation before as well.

I would not have thought my panel adjustment would have impacted my usage like this or I wouldn't have don it. But that vac and saw are power hogs for what they are, 12.5a and 10a respectively, and I can't see anything else that changed to cause this issue other than my different array layout.

Today I got a 125' 8/2 wire and am essentially going to make a monster extension cord with it and see if it helps me, as if voltage drop with my distance is the problem. But now I'm wondering if it is not as much the distance as it is the array is just not supplying the necessary voltage in this layout. I would like to think my system would allow me to do what I'm trying to do in the dark off batteries alone, but maybe not.

 

[eXodus]

for the amount what that cable costs you can also buy a few more solar panels? and just leave them at the house?

Otherwise
Over a 100 meters - 330ft I would run AC Put your batteries and inverter in a Shed/Box and put them out in the sunny field.

The drop is negligible at 110V. When you are going to buy cable - buy a 10 gauge 4 conductor or thicker So you can run 220V at a later time.
You can either drop in a network / phone cable and use some of the conductors to switch the Inverter on and of.

Or build something with Powerline Network.