Solar wiring size

[SPLETS]

I just purchased a Maxeon 415w solar panel for my boat with a Victron 100/50 charge controller. The wire run should be about 27 feet, what sized wire should I run, 8awg or is 10awg sufficient? I have read several articles online, but they have just confused me

Here is the info on the panel.

Thanks

 

[Stu Jackson]

I have read several articles online, but they have just confused me

What confused you?

 

[SPLETS]

Ha, I should have mentioned that. Figuring out how many amps this panel puts out to determine the gauge size. One website says to divide the # of watts by the voltage. So in my case 415w divided by 40.7v = 10.19amps. So according to Renogy's website, they say 14awg is fine, but it sounds too light?

 

[Davidasailor26]

Are you wondering about the gauge from panels to controller or from controller to batteries? From the panels to the controller the voltage is pretty high so the amperage is quite low (under 7A), so that part is not very demanding. If 27 feet is the total round trip 10 AWG should be fine for that.

If you’re asking about the run from the controller to the batteries and that’s 27’ round trip the requirements will be more demanding. For that you’d be looking at 8 AWG if you don’t mind a 10% voltage drop, or 4 AWG if you want to stay under 3% drop.

Here’s the table with all of the recommendations - http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

Also, the two pictures you posted in your original post have pretty different specs in a key measure - one says the open circuit voltage is 80.5V and the other says 40.7V. Are they for the same panel?

Edit: Don’t use the Blue Seas chart for the high voltage side. The percent voltage drops are for 12V only.

 

[Hello Below]

Also, the two pictures you posted in your original post have pretty different specs in a key measure - one says the open circuit voltage is 80.5V and the other says 40.7V. Are they for the same panel?

This calculator works for whatever DC voltage and current you are considering,
DC Wire Size Calculator (omnicalculator.com)

 

[jssailem]

Confusion is normal.
What does the 27ft represent. On a 46ft boat I assume that is the distance from the panel box connection to the batteries. If this is this is accurate than you need to consider the total run as being 54ft when addressing DC wiring. The BlueSea chart is a reliable tool.

Looking at the Installation manual for the Maxeon panels they suggest 15amp fuse for the X series panel and 20amp for the MAX3 panel. This is based on the wire and I am guessing that is the wires of the panel.

The maximum series fuse rating is 15A(X-Series), for MAX3 and MAX6 modules it is 20A.​

https://maxeon.com/us/sites/default/files/2024-01/Safety%20Installation%20Manual%20UL%20Certified%20product_%20544753%20Rev%20E_combined.pdf

​

The manual also provides more detail regarding the electrical characteristics of the panels they build.

​

Solutions are in the details. Identify the specific panel rating and it will lead you to the correct performance of the panel (power out put). This will identify the required wire specifications you need for your install.

 

[SPLETS]

I was looking for the wiring from the panels to the controller.. Are you asking round trip, panels from the panel to the controller and back to the panel, that measurement would? If so that would be 54'.

This is the mfg's specs. https://es-media-prod.s3.amazonaws.com/media/components/panels/spec-sheets/Maxeon_405-420_watt.pdf

This is the sellers website info.

 

[SPLETS]

thanks

 

[dlochner]

I was looking for the wiring from the panels to the controller.. Are you asking round trip, panels from the panel to the controller and back to the panel, that measurement would? If so that would be 54'.

In DC wiring the wire distance is always the round trip, the length of the positive and negative wires, in your case from the panel to the controller an back again.

The Panel produces about 6 amps at 61v under load and 6 amps at 81v open circuit. Using the ABYC Ampacity chart 18ga Marine wire rated at 105°c wire can handle 20 amps. So in theory, you could use wire that small. In practice, it would be nuts to do that.

The Blue Sea Voltage drop calculator does not give the option for 80v or even 60v. The closest the Blue Sea calculator can get is 15a @ 32v which is 480w. The calculator says 10ga for a 3% loss. You should be fine with 10ga.

The reason this works, is wire is rated for amps, not watts. The higher the voltage the lower the amps required to get the same wattage. The math is simple for DC, volts * amps = watts. With higher volts smaller diameter wires are required.

The controller will take the high voltage low amperage current and convert it to low voltage high amperage current. So it will be necessary for the installer to calculate the wire sized from the controller to the battery.

 

[Davidasailor26]

Here’s the table with all of the recommendations - http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

I need to correct myself on that. The Blue Seas chart is only good for the 12V side of the system, despite it not having that caveat made clear. At higher voltages a 3% voltage drop is a lot more forgiving. The other voltage calculators posted above are more appropriate for the higher voltage side.

 

[SPLETS]

Thanks for clarifying that.

 

[billjoye]

Easy: 10 awg. default size of mc4 solar connectors are 10 awg.