Solar Panel Extension Gauge

System

This discussion was created from comments split from: Anyone Carry a Spare Battery?.

rkj__

ScottG said:

Alas, the real-world verdict on the emergency charge cable will have to wait. With mostly decent weather I kept up just fine for nine days with solar alone. However, I did have to deploy my nearly 40' of cable to get the suitcase into full sun for a few hours each day! I do like my trees, but I can see the advantage of the extra wattage @Ratkity mentioned when conditions are less than optimal.

Moving that extra wattage around, now that's another story...  :-)

What gauge wire is your extension cable?

ScottG

rkj__ said:

...

What gauge wire is your extension cable?

My cables are 12g. One is almost 30', the other is ~10'. I made them out of lengths of industrial power cord I already had lying around. Yes, I know about voltage drop. If I were plunking down actual coin (and the cable I'm talking about is very expensive and not readily available at the happy homeowner big box) I would have used something heavier.

That said, it works fine. I have my controller mounted at the battery and still get upwards of 18V from the panel in full sun (most of which goes to waste anyway with a PWM controller).

Engineer-types can fret over voltage drop all they want, but 40' of 12g that gets your panel into the sun always trumps 39' of 8g that keeps it in the shade!  ;-)

rkj__

ScottG said:

rkj__ said:

...

What gauge wire is your extension cable?

My cables are 12g. One is almost 30', the other is ~10'. I made them out of lengths of industrial power cable I already had lying around. Yes, I know about voltage drop. If I were plunking down actual coin (and the cable I'm talking about is very expensive and not readily available at the happy homeowner big box) I would have used something heavier.

That said, it works fine. I have my controller mounted at the battery and still get upwards of 18V from the panel in full sun (most of which goes to waste anyway with a PWM controller).

Engineer-types can fret over voltage drop all they want, but 40' of 12g that gets your panel into the sun always trumps 39' of 8g that keeps it in the shade!  ;-)

12ga sounds plenty nice.

I wanted an extension as well, with the SAE connectors for my pannel.  All I could fine were 16 or even 18ga.  I went with 25ft of 16ga.  Sure, there will be losses, but in full sun, I think I'll still be doing more than zero charging.  I'll keep the controller on the battery side of the extension. 

I used this calculator for doing the math:

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=5.211&voltage=18&phase=dc&noofconductor=1&distance=40&distanceunit=feet&amperes=5&x=62&y=24

rcuomo

I purchased these 20’ 10 gauge extension cables to work with my Renogy suitcase. 

Ratkity

I like the 10g cables with the ready-to-go MC4 connectors (or if you need, Zamp connectors). I say that about the factory connectors because they are usually crimped better than I can do.

ericnliz

@rcuomo, & @Ratkity, I have the same cables & really like the connectors. Basically plug & PLAY!

jkjenn

Ratkity said:

I like the 10g cables with the ready-to-go MC4 connectors (or if you need, Zamp connectors). I say that about the factory connectors because they are usually crimped better than I can do.

I have been using 8# cable but I am tired of the bulk. If I go back to FT, I will go back to 8# but for vacation, I think 10# is more than sufficient and easier to deal with. I bought Windy Nation because they were as little less expensive. 

rkj__

Now that I have a multi-meter, I should be able to check the voltage reading with and without the extension.  If/when I get around to it, I'll share the results.

Verna

@jkjenn, I have a 20’ marine 10 gauge cable that I made up with SAE connectors for my solar panel suitcase.

I have checked it only to tenths of a volt and any loss in voltage was not noticeable at that length.  This gives me 35’ total in length if I need it.

The only bad thing about the cable is that the insulation is white and passerby’s think it is 110V Rolex wiring, which it is not.  

The weight is less than that of a 25’ water hose, by the way. And being a marine cable, it is very flexible in any type of weather. I bought the length of cable from a marine shop outside of San Diego 4 years ago. 

jkjenn

Verna said:

 
The only bad thing about the cable is that the insulation is white and passerby’s think it is 110V Rolex wiring, which it is not.  

The weight is less than that of a 25’ water hose, by the way. And being a marine cable, it is very flexible in any type of weather. I bought the length of cable from a marine shop outside of San Diego 4 years ago. 

My 8" had the white insulation and the same look. It is about 50'. I had a trolling motor connection on one end and MC4 on the other. Crimping 8# wire is a real hassle, too.