I just bought this boat and was going to do a full charging system upgrade, but the insurance company balked at my plan to use LiFePO4, so we decided to go a different route and just add solar to what’s already there. We will fight the insurance company later.
As for what’s already there, it’s this:
I’ve asked for help on a few other forums, and everyone seems to want to tell me how to make the existing system better - but that’s not what I’m interested in right now. I have limited time, and the existing system worked fine for the previous owner for 26 years, so it will work for my plans for the next 12 to 18 months or so. All I want to do is add solar so I don’t have to run my genny so often if I choose to spend five or ten days at anchor. It doesn’t need to be enough to stop me from running it at all, but just cut down on the time I would otherwise have to.
This is the rough plan I came up with:
The inverter/charger is tied to an “inverter bank” with 2 8D24 200 AH FLA batteries. That bank is isolated from the three other batteries in the system - and those three batteries are isolated from each other. The inverter bank charges directly from the inverter/charger, as do the other three, but they pass through a diode that keeps them isolated from each other. When running, the engine alternators also pass through the diode to keep those three batteries charging. The three switches at the top are quick disconnects if you want to disco everything to any individual start battery.
The Generator battery stands alone - it’s the only one that will not be charged by solar.
The two 8D24 “Start” batteries double as house DC power and can be run individually or in parallel using the 1, Both, 2, Off switch at the DC distribution panel.
So, what I want to know is whether the solar plan above will work. Will it charge when nothing else is charging and otherwise sit there and play nice with other things that ARE charging? If that’s not enough solar for my needs, I can always expand - I just want to know if the design is sound.
Please read the MPPT manuals and look at the wiring diagrams. The negative from the panel goes to the MPPT input and then a negative from the MPPT output goes to the batteries. The solar panel negative DOES NOT connect to the batteries as you have shown. This suggests a lack of basic knowledge, consult a marine electrician if unsure.
You can not really have 2 MPPT controllers on one solar panel array. These work by adjusting the panel voltage to get the maximum power and you will have 2 independent controllers trying to control the panel voltage.
The simple solution is one panel per controller.
You could keep the panels as one bank with one MPPT and then split 3 ways but that would mean uneven charging if the banks are all at different voltages. You could put a single controller to charge the inverter bank and then 2 x Orion DC to DC chargers to charge the 2 secondary banks and do away with the ArgoFET. The DC to DC would be set to only charge when the inverter bank was perhaps above 13.8V.
The solar panels do not need fuses between the panels and the MPPTs. Solar panels can only produce a certain current, make sure the wiring and MPPTs are rated above this = no fuse required because there is no way that they can generate too high a current.
As said, consult an experienced system installer.
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Thanks for the response.
I’m definitely a beginner, but I have some experience with 12V systems in general, just not much with Solar.
I like the idea of a single controller with DC-DC chargers. Keeps it simple.
So I did some more reading, and I think this may be the correct config and equipment.
The Solar Array will charge only the Inverter Bank as it’s the most important. I will configure the Orion XS to kick in to charge the start/house batteries once the Inverter Bank reaches 13.8 volts.
I am using the Argofet to keep the house batteries isolated from each other and still only use one charger input. DC draw at anchor is minimal and mostly driven by the Starlink. The fridge and freezer on the inverter are the big draws.
The MPPT Control can monitor/configure the controller, and the batteries/banks will be monitored using the BMV700s.
If I find that the two 360W panels aren’t enough, I can add panels and upgrade the controller.
OK, that system will work as you expect. You probably need to reduce the charge current on the Orion XS otherwise it may cycle on and off a lot as it can take more current than the solar delivers.
The one error is between the inverter batteries negative and the inverter BMV you have the solar negative and the common negative. The solar negative and the common negative need to be connected to the inverter side of the BMV. Otherwise the BMV will not measure the charging currents from the solar and to the Orion XS.
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What would be the consequences of just running the MPPT output directly into a 3-bank Argofet and letting the bank and the two batteries charge directly from solar without using the Orion XS?
Just wondering if maybe I made things a little too complicated.
This would be simpler. Your layout with the Orion XS will always prioritise the inverter batteries but you will need to make sure that the XS current is limiting. With the Argofet whichever bank is the lowest voltage will initially take more of the charge current, so in a way that means the one you use more gets more recharge. It will also stop you getting the situation where your XS is cycling on/off or trying to control current is the solar is low. You could get a 3 bank Argofet and set the system up and then if it does not work, take 1 bank off the Argofet and add a DC to DC charger.
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Thank you.
I think I may do that.
The primary goal was to make this as simple and cost-effective as possible, leaving room to expand if necessary.
