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Hello all, My current solar array was coming up about 50% short every day while in Bahamas this winter. It's also not wired properly for current protection and no useful shutoffs. So I want to double my panels and wire it all properly. Attached is the design I came up with. The current system has 4/0 wiring from the house bank up to the fly bridge to power the 24 volt davit. This made the solar connection very simple to get back the the house bank. I will be using that again. It's not on the diagram but I'm also replacing my inverter with a Multiplus inverter/charger. The Multiplus will allow me to divert any over capacity solar to the 120VAC hot water tank heating element once the batteries are topped off. That will almost eliminate need for the gen other than air conditioning.

I'm looking for comments and any suggestions that I may have missed.

Thanks,

Joe

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adding better diagram

A couple of thoughts:

if you're using a Victron MPPT the MPPT needs to be at the same temperature (+/- 5 degrees C) as the battery to avoid temperature compensated charging issues at the battery. Perhaps the BMS handles this for you.

by connecting the ground at other than the boat's common ground terminal you are creating a ground loop. That's usually not desireable.

there are more connections and terminals than needed between the positive MPPT terminal and the battery. Each terminal/connection is a voltage drop point.

I would look at pulling wires from the panels to where the battery is, place the MPPT there, and take hot and ground straight off the BMS (or battery, if there weren't a BMS).

I don't like circuits where wiring is shared. If the davit motor fails and fuse blows, the solar array will also fail. That might work for you as the installer *and* designer/owner as you know that's the design. When I find that type of wiring I remove it and pull new wire all the way home to battery, common ground, or circuit breaker panel.

Hi Rob, Thanks for the comments. After reading them and looking it over, I realized I had all the grounds wrong. I actually showing how they are now and not what I wanted to do. I've changed the drawing around cleaning that up and keeping your comments in mind. I was able to remove a couple of extra connection points but I think I'm at the minimum and still have fuses and shut offs where needed. I took a close look at moving the MPPT's to the batteries but I think I would have to use 6AWG for the distance and current and there is no way I can route that down there.

I'm not really concerned with the temperature compensation since these are LifePO4 batteries. The BMS will deal with the temp extremes if it ever sees them.

The last thing is I isolated the davit motor and MPPT's with their own fuses in the Victron distributer. They still share the 4/0 common feed but the each can blow a fuse without taking the other out.

I attached the new drawing. I'll be getting to this next month, so still looking for comments from anyone.

Thanks

Joe