Proposed Small Solar Setup

[Northstar1014]

Hello all,

I am adding a small solar panel to my Beneteau 343 -- my goal is for it to provide supplemental charging over the course of the workweek so that I have a fuller battery bank at the start of the weekends (I am on a mooring and have a 60 amp alternator that is known to not be the most optimal alternator for battery recharging)

Below is my proposed setup. For anyone with experience with solar, would appreciate any thoughts - I want to be sure it is wired appropriately and safe. Thank you!

 

[AaronD]

Good work planning and diagramming ahead of time!

Two things that weren't 100% clear (to me) in your layout. So, maybe you've already accounted for both, but just in case:
1) You want the 25A breaker next to the battery bank. It's to protect the wire from the possibility of huge amperage from the battery (the solar system is current limited, and can't ever produce enough current to overheat the wire). I believe ABYC standard is that it be within 7" of the battery terminal. If that's not practical with a breaker, you can use a terminal fuse block like https://shop.sailboatowners.com/prod.php?963/Battery+Terminal+Fuse+Blocks (fuses at https://shop.sailboatowners.com/prod.php?10499/Battery+Terminal+Fuses).

@Maine Sail has discussed this in a few places. You can search his forum posts and his site (marinehowto.com) for more details.

2) You want the negative lead from the solar controller connected to the shunt, so your battery monitor will see (and count) the current flowing from the solar system into your batteries. The shunt should be the _only_ connection to the battery bank negative.

Hope that helps (you or some other reader).

 

[MikeHoncho]

I'd plan for future expansion. That's alot of work and materials for 60 watts, it would be a shame to have to do it all over again if you wanted to increase to 200.

 

[BarryL]

Hey,

A few years ago I installed a small kit I bought from Defender.
https://www.defender.com/product3.jsp?path=-1|328|2290044|2290049&id=2708256
I ran the output from the controller directly to the 'house' battery. Simple and easy. If I want to charge all batteries I just sent my battery switch to 'all'

Barry

 

[AaronD]

I'd plan for future expansion. That's alot of work and materials for 60 watts, it would be a shame to have to do it all over again if you wanted to increase to 200.

According to @Maine Sail (https://shop.marinehowto.com/products/victron-75-15-mppt-controller), his Victron 75/15 should be able to handle 220 watts, and the AWG 10 wire should as well, at least up to a one-way wire run of ~12-15'. I think you generally want to size wire for <= 3% loss at your target current, and that looks OK (at least per my 30 seconds spent at https://www.calculator.net/voltage-drop-calculator.html).