Need the solar/power pros to weigh in

luthj

Engineer In Residence
You can just put the meters probes on both ends of the run. If the panel is making 16V, and the voltage at the solar controller is 14V, then you have a 2V drop.

If you know the current and wire gauge, you can plug it into this calculator Remember to include the full round trip distance, not just one leg.
 

TantoTrailers

Well-known member
I'm not sure the current that my panels will be outputting so I'm not sure what values to enter. The round trip from PV- on controller to PV+ on controller will be about 30' (10 to panel 1, 10' between panel 1 and panel 2, and 10 foot back from panel 2 (connected in series). 12gauge or 14gauge? Need anything beefier than that?
 

dwh

Tail-End Charlie
#12 is fine with plenty of extra margin. Low-voltage landscape lighting cable has a pretty tough insulation and is also quite flexible.

The MPPT is going to adjust the operating voltage of the solar loop to get the most watts, so voltage drop doesn't matter anyway.
 

TantoTrailers

Well-known member
^thats the panel I am looking to use 2 of. Not sure if these details help: High performance: light transmittance up to 93%. Cell Efficiency: 22. 3% (one of the highest). Module Efficiency: 19. 2% (one of the highest). Maximum Power: 120W. Tolerance Wattage (e. g. +/- 5%): +/- 5%. Maximum System Voltage: 600V DC. Open-Circuit Voltage (Voc): 26. 4 V. Short-Circuit Current (Isc): 5. 9 A. Power Tolerance: 0=+3W. Max Fuse Rating: 10 A. Fire Safety: Class A. Temp Range: -40F to 185F. Charge controller PV Wire: 10 AWG with spade connect easily connects to various charge controllers each wire is 76 inches long. Certifications: CE, ETL, TUV and RoHS.
 

dwh

Tail-End Charlie
High performance: light transmittance up to 93%.

Anti-reflective coating on the cells.


Cell Efficiency: 22. 3% (one of the highest).

How much of the light actually makes electricity.


Module Efficiency: 19. 2% (one of the highest).

Cell efficiency plus losses from the internal wiring.


Maximum Power: 120W.

Rating at STC (standard test conditions).


Tolerance Wattage (e. g. +/- 5%): +/- 5%.

More or less.


Maximum System Voltage: 600V DC.

Can string them in series to a max of 600v, which is way more than the 75v a Victron 75|15 can handle.


Open-Circuit Voltage (Voc): 26. 4 V.

No load voltage.


Short-Circuit Current (Isc): 5. 9 A.

Dead short max possible amps.


The rest is standard boilerplate stuff.
 
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dwh

Tail-End Charlie
#18 would carry the load, but will reduce your power harvest by some percentage.

And will break easily. Like by being stepped on. Or rolled/unrolled too many times.

Doable. Not recommended.
 

TantoTrailers

Well-known member
I was afraid of that answer....anything that can potentially result in reduced output from my panels is definitely not what I want. I will see what connectors I can find for the 12# wire. TY!
 

dwh

Tail-End Charlie
Those connectors are for the ballasts of florescent light fixtures. As in very high voltage, very low amperage, connect/disconnect once every 10 years when a ballast fails and needs replacement.

Plus, push-in wiring - like what is called "backstab" on a receptacle - is utter crap. Prone to various failure modes.
 

TantoTrailers

Well-known member
Thanks man this is exactly the info that I need! Any good connectors that you know of that are smaller than the beefy Anderson battery connects?
 

luthj

Engineer In Residence
18 gauge at 30Ft would be around 5-6% loss with 6A current. You can decide if that loss is acceptable. I know you are asking for easy answers, but we are trying to provide you with the instructions, so you can teach yourself how to calculate voltage drops.
 

TantoTrailers

Well-known member
Easy answers asap is the name of the game in my (current) industry! I do appreciate all of the input, it has been extremely helpful and I am learning a lot. I am more of a monkey see monkey do type of learner than here is the steps figure it out kind. All the same in the end I suppose. I will be playing with the power loss tips to see how different gauges and connectors affect things BUT for my end game setup I am going with 12# landscape wire with 30A Anderson Powerpole connectors. Those seem small enough to fit inside my case when its closed up and stowed away. Looking forward to getting all of this tested out. I will have everything by mid week next week and I have a shakedown trip planned next weekend in a fairly open space where I will get plenty of sun if the clouds allow.
 
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