12v or 24v

[Jeff in Ferndale Wa]

After a couple years of "thinking about it" I purchased two Renogy 100w solar panels and a 40w MPPT controller back in November.
I finally installed the panels today and am ready to wire it.
Currently running 2 6v LA batteries, with thoughts of going to lithium in the future.
The controller literature says it automatically detects 12v or 24v systems.
I assume that means 12v or 24v into the controller, and the controller will automatically send 12v to the batteries.
My question: is it better to connect the panels for 12v or 24v input into the controller?
Thanks in advance for the help.

 

[Mark_K5LXP]

A 40W controller is entirely too small for 200W worth of panels. Series vs parallel will depend a bit on what kind of panels they are, and running some numbers regarding the wiring you have going to them. There can be some efficiencies gained by going with the higher voltage but they're not universal, in all use cases.

Mark B.
Albuquerque, NM

 

[Jeff in Ferndale Wa]

A 40W controller is entirely too small for 200W worth of panels. Series vs parallel will depend a bit on what kind of panels they are, and running some numbers regarding the wiring you have going to them. There can be some efficiencies gained by going with the higher voltage but they're not universal, in all use cases.

Mark B.
Albuquerque, NM

Sorry Mark, meant 40A controller....
Wiring is what came with the panels, and i will make them as short as possible.

 

[DonTom]

I assume that means 12v or 24v into the controller, and the controller will automatically send 12v to the batteries.

Since the VOC (Voltage Open Circuit) is usually ~21 volts for a single panel, I wouldn't think 12V would be included in that for input to the controller.

What is the make and model of the controller? Perhaps we can find the actual specs.

-Don- Redcrest, CA

 

[Jeff in Ferndale Wa]

Since the VOC (Voltage Open Circuit) is usually ~21 volts for a single panel, I wouldn't think 12V would be included in that for input to the controller.

What is the make and model of the controller? Perhaps we can find the actual specs.

-Don- Redcrest, CA

It's a Ronogy Rover 40A.
to clarify, I'm asking whether it's better to hook up parallel or series.
Since I posted this question, I've done some more Googling, and I think it's better to wire parallel vs series and I wonder if you all agree or disagree?
"

Parallel Wiring: Pros and Cons​

Advantages:

1. Shade Tolerance: In a parallel setup, shading on one panel has minimal impact on the performance of the others. This makes parallel wiring a better choice for locations with variable shading.
2. Stable Voltage: Parallel wiring maintains a consistent voltage that matches the output of a single panel. This makes it easier to align with the voltage requirements of inverters and battery banks.
3. System Redundancy: If one panel fails in a parallel system, the other panels continue to operate, ensuring continued energy production and increased system reliability.

 

[DonTom]

I wonder if you all agree or disagree?

I chose series. And in both of my motorhomes. See the thread here.

Series is best for my setup for several reasons. But no matter which you choose there will be advantages and disadvantages, and you have to decide what is best for you.

Kinda like do you want a Class A , B or C motorhome or do want to tow something with a truck? Should it be small or large? What works best for one may or may not be the best for somebody else.

-Don- Redcrest, CA

 

[DonTom]

This one?

 

[John From Detroit]

When it says 12 or 24 volt systems it is talking about the batteries.. Voltage in from the panels depends on sunlight a "12 volt" panel can put out less than six or more than 30.

 

[Jeff in Ferndale Wa]

This one?

View attachment 1324283


View attachment 1324282

yes,this one.

 

[Jeff in Ferndale Wa]

When it says 12 or 24 volt systems it is talking about the batteries.. Voltage in from the panels depends on sunlight a "12 volt" panel can put out less than six or more than 30.

a light came on in my head this morning, and I understand this now.
Thanks