We have a 120 watt portable solar panel -- it almost always generates enough power to top off our battery every day.We usually park the trailer in the shade and put the panel in the sun. We have a 30 foot cord -- heavy gauge (I think 12 gauge). Very little voltage drop.But there are times when we wish we had a longer cable -- 50 feet would do the job for sure.So that is my question – I know that a ten gauge cable would be ok, but it is thick and heavy and awkward to deal with. Would a twelve gauge cable cause a significant voltage drop? Are there reference tables that indicate how much of a drop is caused by a cable of X gauge at Y feet?Thanks in advance for your expertise!

Worse case scenario based on the specs below.100 watt panelOutput 18 volts, 5 ampsDistance 100 feet (12AWG)11% voltage drop10AWG would be about a 6% drop

A gauge 10 cable with a length of 15 m, 50ft, has a maximum current of 5 Amps. This is for DC wiring. https://www.engineeringtoolbox.com/amps-wire-gauge-d_730.htmlThis has a user chart you can put in your numbers. https://www.renogy.com/calculators#tab_solar-cable

If you want some cables that are easy to handle, rolls and unrolls nicely, and has a flexible, durable jacket, buy some fine strand welding cables like these. I’ve made a lot of custom length cables from this, crimping my own lugs on the ends and it’s a joy to work with. You’ll need the appropriate size lugs and a crimping tool that can handle the size. 6 Gauge 50’ Welding Cable:):)

Luckily the panel operates over a wide range of voltages.I use 12g landscape wire

Lots of good tips so far -- keep 'em coming! I had not thought about welding cable -- I bet that is available at Harbor Freight -- they have a whole welding aisle.

Need advice on 50 ft cable to portable solar panel

Bobbo
Explorer II
Oct 13, 2021
profdant139 wrote:
I am going to display my ignorance here, so be ready to laugh. How do I tell what kind of controller I have?? It is built in to the portable panel -- but I bet I could un-attach it, with enough brute force. ;)

I'd be willing to bet it is PWM since it came on the panel. My recommendation, get a good MPPT (I chose Victron SmartSolar) and put it at the batteries. Then disconnect your panels from the OEM controller and run them directly to the MPPT controller.

One caveat. I have not been able to find a good weatherproof MPPT controller. You will need to protect it if it is going to be exposed to the elements.
jaycocreek
Explorer II
Oct 12, 2021
What portable solar panel do you have?
profdant139
Explorer II
Oct 12, 2021
I am going to display my ignorance here, so be ready to laugh. How do I tell what kind of controller I have?? It is built in to the portable panel -- but I bet I could un-attach it, with enough brute force. ;)
jaycocreek
Explorer II
Oct 12, 2021
I don't think you will notice any difference,the way there aimed is far more important for incoming amps/watts...

Two 100 watt portable panels laying flat on my truck camper roof..

Minutes later,standing on the roof aimed at the sun..
ktmrfs
Explorer II
Oct 12, 2021
time2roll wrote:
profdant139 wrote:
Very interesting points about moving the controller -- I will have to experiment with that to see how much difference it makes.
Panel is probably 18 to 22 volts and is cut to 14.x at the controller.

If the 18 volts drops to 15 through the wire to the controller it may not matter much as the controller will still put 14.x on the battery.

If the controller is at the panel you have 14.x going through the long wire and limiting power to the battery.

for a PWM controller at the battery, as long as voltage drop doesn't get down to below around 15V drop will have almost no effect on charging current. For a MPPT controller output may drop some due to the power loss in the cable that the MPPT controller normally could use. Worst case MPPT controller will end up delivering the same power as a PWM controller when the voltage drop gets big enough.
time2roll
Nomad
Oct 12, 2021
profdant139 wrote:
Very interesting points about moving the controller -- I will have to experiment with that to see how much difference it makes.
Panel is probably 18 to 22 volts and is cut to 14.x at the controller.

If the 18 volts drops to 15 through the wire to the controller it may not matter much as the controller will still put 14.x on the battery.

If the controller is at the panel you have 14.x going through the long wire and limiting power to the battery.
Tom_M1
Explorer
Oct 12, 2021
ktmrfs wrote:
buy a 12Ga 3 wire extension cord, cut the ends off it and solder the green wire to either the black or white on one end do the same at the other end soldering to the same color you did at the first end.
Another approach is to make adapter plugs to go on each end and jumper the wires at the adapter. This way you have a dual purpose cable. Remove the adapters and use it as a regular 120 VAC extension cord.
2112
Explorer II
Oct 12, 2021
How about making a 20ft 10AWG extension cable. Place your panel where you want it. Add the extension if the existing 30ft doesn't reach the camper.

Do you have a PWM or MPPT controller?
profdant139
Explorer II
Oct 12, 2021
Very interesting points about moving the controller -- I will have to experiment with that to see how much difference it makes.
time2roll
Nomad
Oct 12, 2021
I would get some #10 and accept what it is. You may not get full power but certainly more than fighting the shade.
Controller should be near the battery.