Need help with wire and fuse size on solar install

[keysbottles]

I'm in the process of buying components and misc. parts for a solar install on my RV.  I plan to attend the 2020 RTR and hope to find someone to install it for me.  I'm too old (73) to be climbing on the RV roof.  I have been reading your comments on this site to try to educate myself but solar seems to bounce off my thick skull, so I need some help. 

Below is a list of what I have and what I need.
What I have
(2) 250 watt, mono,24 volt, sunpower panels (Santan)
 (1) ECO-WORTHY 40A 12V/24V MPPT  controller w/ monitor
(2) 12 volt marine batteries  I know these are not ideal but are in good shape so I will use them for now. They were in the RV when I bought it.

What I need
Wire sizes between controller and batteries, and the panels and controller
Where do I need fuses and what size
best voltage to wire the panels
What else do I need?

15 feet panels to controller
15 feet controller to batteries  Will this be an issue?

I'm open to any suggestions and information you may offer.  Thanks in advance  Don

 

[keysbottles]

Hey folks,  why no help?  Am I asking for too much information?  Did I say something in the post that offended Y'all? :s

 

[highdesertranger]

yeah that's weird. usually a lot of members chime in.

1. 10 gauge PV(photovoltaic) wire between the panels and controller.
2. I would run the panels in series because with the MPPT controller you will get more amps into the batteries. also the higher voltage makes the 15ft run more efficient.
3. I would try to move the controller closer to the batteries.
4. I would run the largest wires the controller allows from the controller to the batteries.
5. fuse as close to the batteries as possible fuse size depends on overall use
6. fuse or switch at the controller from panels this is mainly for servicing.
7. a battery monitor comes in handy

highdesertranger

 

[keysbottles]

thanks highdesertranger

 

[tx2sturgis]

If you can get the controller 6 feet or closer to the batteries, then probably 8 gauge wire will be fine for that section.

I recommend marine style battery terminal fuses (MRBF) if you have the room. They protrude a couple of inches above the battery terminals. This is what they look like:

https://powerwerx.com/mrbf-terminal-fuse-block-300a

These fuses are expensive but they provide fail-safe protection in the event that something bad happens in your wiring or a component downstream. Then you can also use smaller, less expensive ATC fuses in a fuse panel, for your various branch circuits.

A 50-80 amp fuse should be sufficient for normal stuff, unless you are planning on an inverter. Then you will need to use a much larger fuse, depending on the recommended amp rating of the inverter.

 

[AuricTech]

For wire sizing, you can use the Voltage drop calculator in my .sig file.

 

[regis101]

There is also a Sticky at the top of this forum that will most likely help you out.