How Far Can You Run Solar Cables | Avoiding Line losses

Is there a limit to the length of solar cable or wiring between your panels and your charge controller? This is a common design criterion we need to consider in our DIY solar projects because the best sun might be hundreds of feet away from our system equipment. I will walk you through how to calculate line losses and a few factors you can tweak to run a long distance while reducing the impact of your losses.

DISCLAIMER: This video and description contain affiliate links, which means that if you click on one of the product links, I’ll receive a small commission.

[everydaysolar]

DISCLAIMER: This video and description contain affiliate links, which means that if you click on one of the product links, I’ll receive a small commission.

[Gladishification]

You can just put the station beside the panels and run the extensions through the yard. That way you can look at both meters in real time simultaneously. You having the station in the front yard or beside the panels doesnt matter as the loss in the length of the cable is what your calculating.

[SarahStuff-pu]

Willing to bet you still will be getting a bill monthly for the line charges even if you draw nothing from the Grid....but overall nice setup. Quite a few forget them line charges when calc ROI from solar, when deciding on solar keep the entire system cost in mind and what the solar might actually reduce. Net metering 1:1 sounds like there will be no charge, but you are charged for transmission fees, need to include those as well....

[Ulbre]

Great info. This makes a difference as my preferred solar array, on top of a new carport, is a detached one around 60 feet (maybe 100 cable feet to inverter) from my house and I was wondering what losses I would have. This video shows me it will be quite okay. Thanks.

[Sylvan_dB]

In series where you doubled the voltage so half the current carries the same wattage, not only do you save because lower current means lower loss, but you also save because the loss is a smaller portion of that higher voltage.

In other words, at 36 volt you were getting approximately 10% loss (for ease of calculation) or 3.6v loss. If you cut the amperage in half, you will lose only1.8v. If you were still at 36 volt that would be 5%, but as you are now at 72 volt that is 2.5%. It's all math, and what that calculator is really doing for you is computing the resistance of the gauge and length of wire you specify. You can look up resistance per foot and do all the math yourself. Don't forget that the distance is double - the circuit includes the positive and negative wires.

amps = volts / resistance or volts = amps X resistance
also
power = volts X amps

I like to target no more than 3% loss but 5% is probably okay. 10% is a LOT of loss!

[jumemowery]

Thank you for the video. I'll be running about 120 feet of 10 gauge wire. I'm definitely going to go in series. I appreciate the information very much!

[hu]

Good vid! There is another consideration which few talk about. It will depend on your load, and I do not know what these charges controllers in this regard. But maximum power will only be transferred if the source impedance matches the load impedance. In this case, that would be the source resistance, and the load resistance. Just divide the voltage that you get at the load from your solar installation divided by the current that you are getting, and that is the source resistance of your solar panels plus the wire. Ideally, you want your load to be this same resistance for maximum power transfer. Those harbor freight panels have about three ohms resistance each. So, depending on how you wire them, and how much line wire length you have, you’re going to have a different amount of resistance. For a solar water heater element the resistance is also the specifications voltage divided by the specifications current, which is usually 7 to 12 ohms. So make your solar panel arrangement plus the wire resistance, the same as this and you can optimally heat water directly. If you have a charge controller, then I’m not sure what kind of load of presents to the solar panel. One would hope that it is adaptive and changes, its input resistance, according to what the panels are providing. But cheaper charge converters may not be so smart.

[tedrymarcsuk]

Very useful information. Thanks for running and explaining this test!

[davidanderson]

Thanks for the video, been following your work on both channels, very helpful and useful information - would really like to see how well any of those ecoflow's do in your outdoor shed during an IL Winter!

[MTNPANTS]

Great explanation and example. This helped me decide how to configure my eco flow set up.

[TomCee]

What I found interesting was reading a higher voltage at the Ecoflow than at the panels. That’s some good wire 😂.

[JanicekTrnecka]

simple rule: if its low voltage, its impractical to run long wires, its good enough to use it locally, few meters or ten-ish is maximum. If you can go up with voltage, longer cable runs are ok if you are not pushing the cables on their max current rating. If this becomes a limit, just bump it up and use next gauge cable...

[MegaCyrik]

Thanks for another interesting video.

May i suggest you take a look at the pzem watt meter models. The one called pzem015 can handle up to 200vdc and usually comes in 50, 100, 200 or 300a models.
The price range is about 10$ to 20$ for the 50a-300a.

The other pzem models may only support 100v so make sure you look at the correct version.
This is just a suggestion to the obstacle about max 100vdc you faced. I dont know if they are available in your place.

[garymeissner]

I have seen a lot of solar energy testing done using a Victron Smart Shunt. They even data log for you.

[chippyjohn]

You could just use a dc power supply to show an accurate difference over distance and cable diameter.

[mindbender]

This is why power lines are at 1000's or millions of volts to reduce the cost in wire (lower current higher voltage). Also at that high a voltage they can run for miles and lose very little energy..
The only problems with such long runs is they swing in the wind and can carry quite the static voltage charge even when powered down..
So when you buy an inverter always look for one that has a higher voltage ... That will save you on copper size and run (copper at 12volts has to be very thick) but at 500v which is the sweet spot for inverters right now the current is so low you can get away with smaller gauge wire ..(10-14 depending on length)..

[toom]

Why dont you just lay your cable in a U shape mate?

[JenkinsUSA]

I’ve watched a few of your videos, informative. I have a question, … how did you calibrate the two power meters? I was looking at doing something similar. Keep up the good work 😊

[manabouthome]

The NEC recommends 2%-3% voltage drop in your average power circuits. (That's actually a recommendation. Not a requirement.) But if you lose 3% of a 5000 watt array, that's 150 Watts! It's like wasting a 150 Watt pv module. How much does that cost? ...over time? It makes good long term sense to design for less than 1% voltage drop.

[CHB-Tuber]

Good video — 2 questions please …
I noticed the MC4 connector going into the meter from the panels ….. I believe you mentioned a thunderbolt connector on the panels — is there a “stock connector” for thunderbolt to MC4? … how did you do the connection on the panel side .. clip and replace with MC4 or install thunderbolt connector on the panel side of the extension wire?

Second question .. the series hookup to the EcoFlow … 77v and 72v shows on the meter… the input rating for EcoFlow is at 60v. I believe if amps are exceeded, EcoFlow just clips and allows the max of 15amos… But isn’t 60v the max before breaker kicks in? Could you please provide a bit of detail on this ..