Solar panel wiring setup

[SteveOO]

Hello, I'm about to upgrade my solar/battery system from a couple old panels and batteries to 800watts of 4 bifacial panels and 560ah in 2 lithium batteries. I'm just hoping to double-check my basic wiring plans here to make sure I'm not way off on some parameter.

The panel stats:

Max Power at STC	200W
Open Circuit Voltage	28.1V
Short Circuit Current	9.12A
Optimum Operating Voltage	23.4V
Optimum Operating Current	8.55A
Operating Temperature	-40°F to 194°F (-40℃ to +90℃)
Maximum Series Fuse Rating	15A

I'm planning to wire the panels in two groups of two panels panels in a series, and then in parallel to the charge controller. I believe this gives me a max voltage of: 56.2V and a current of: 18.24A at the charge controller.

They will go into a single Victron 100v/30a charge controller, and I believe power coming from the panels in full sunlight will be well within the range of that charge controller. But... am I off on any of this?
Going full parallel or full series are of course the other options, but this middle ground felt right to me.

Some extra info incase it helps:
The batteries will be directly charged via the main bus by the charge controller (starter battery will be in a separate circuit with the alternator and a small solar panel to keep it topped up).
I'll later add a DC-DC charger from the starter battery to the house bank. I'll have a switch to allow shore power directly to my 120v panel when at the dock, but am not wiring up batteries to charge through shore power at the moment. The inverter does not have 120v pass through, but I want to see if I can get by without shore power charging for now. If needed I'll bite the bullet in the future and swap that inverter out for a victron multiplus.

Sorry for the dense information dump, and thanks for any input!

 

[southofvictor]

The first question that comes to my mind is why not give each panel its own controller and parallel them after the controllers? You’re running a 12v system not 24v correct? What’s your reason for doing the 2s2p configuration?

Seem like you’d get better performance by wiring all in parallel with individual controllers. That way one shaded panel isn’t hurting any of the others.

If it’s lack of space there are smaller form factor controllers than Victron, Genasun makes good ones.

 

[Bolo]

The first question that comes to my mind is why not give each panel its own controller and parallel them after the controllers? You’re running a 12v system not 24v correct? What’s your reason for doing the 2s2p configuration?

Seem like you’d get better performance by wiring all in parallel with individual controllers. That way one shaded panel isn’t hurting any of the others.

If it’s lack of space there are smaller form factor controllers than Victron, Genasun makes good ones.

Thinking of a smaller solar setup on my E32 and so I’ve been doing some research. The one point I do remember reading is to try and have a controller for each panel because if the only controller you have craps out then you can’t charge but if you have one controller for each panel then on breaking only looses you part of the whole.

 

[SteveOO]

The first question that comes to my mind is why not give each panel its own controller and parallel them after the controllers? You’re running a 12v system not 24v correct? What’s your reason for doing the 2s2p configuration?

Seem like you’d get better performance by wiring all in parallel with individual controllers. That way one shaded panel isn’t hurting any of the others.

If it’s lack of space there are smaller form factor controllers than Victron, Genasun makes good ones.

Thanks for the input. Yeah it's a 12V system but a single panel can put out 28v.
My thinking in doing the 2S2P vs 4 panels in parallel in is that:

• the higher voltage (56V vs 28V) in the cable run to the charge controller is more efficient
• I'm still 1/2 covered by shading drops (vs doing a 4s setup)
• only need to run 1 cable through the hull
• 1 charge controller and less wiring below deck

But yeah the main tradeoff being that I'm 50% more vulnerable to shading drops vs going all in parallel, as you pointed out

 

[Kenneth K]

When I installed my solar, the gist of it that I took away was: Any panels with the similar orientation/sun-blockage issues can be wired to the same controller (multiple panels acting like a larger panel). Any panels with differing orientation/sun-blockage issues should be wired to separate controllers.

My stern-mounted portside panel goes to one controller and my starboard side to another. Victron charge controllers will also "talk" to each other to optimize output between the two. Blog here: https://ericsonyachts.org/ie/ubs/battery-systems-upgrade.921/

 

[SteveOO]

When I installed my solar, the gist of it that I took away was: Any panels with the similar orientation/sun-blockage issues can be wired to the same controller (multiple panels acting like a larger panel). Any panels with differing orientation/sun-blockage issues should be wired to separate controllers.

My stern-mounted portside panel goes to one controller and my starboard side to another. Victron charge controllers will also "talk" to each other to optimize output between the two. Blog here: https://ericsonyachts.org/ie/ubs/battery-systems-upgrade.921/

Good points. I should have mentioned that all of my 4 panels will be mounted together on the solar arch. I don't expect much partial shading in general, should be fully in sun or fully shaded.

 

[SteveOO]

Thinking of a smaller solar setup on my E32 and so I’ve been doing some research. The one point I do remember reading is to try and have a controller for each panel because if the only controller you have craps out then you can’t charge but if you have one controller for each panel then on breaking only looses you part of the whole.

Yeah with my one-controller plan, I'll definitely be bringing a spare charge controller on any long trips.