Don't understand

[Guy]

I am very new to this solar stuff and I am quickly becoming very confused. I have read many posts about either a 12 volt or 24volt system. I understand about hooking up 2 solar panels either in parralle or series. Same as with 12 volt batteries. But if my RV is a 12 volt negative ground system, then I have to leave the batteries in parallel. ( same volts-more amp hours ). But does this mean that I also have to leave the solar panels in 12 volt mode attached to my solar 12v/24v controller or can I put in 24 volts to solar controller and put out 12 volts to batteries?

 

[MrNatural22]

Here’s a good thread.
Thread 'How to go from 12V to 24V system in RV'

 

[FilterGuy]

I am very new to this solar stuff and I am quickly becoming very confused. I have read many posts about either a 12 volt or 24volt system. I understand about hooking up 2 solar panels either in parralle or series. Same as with 12 volt batteries. But if my RV is a 12 volt negative ground system, then I have to leave the batteries in parallel. ( same volts-more amp hours ). But does this mean that I also have to leave the solar panels in 12 volt mode attached to my solar 12v/24v controller or can I put in 24 volts to solar controller and put out 12 volts to batteries?

What kind of solar controller do you have? If you have an MPPT controller, you can pretty much do what you want with the solar panels as long as the voltage from the panels is higher than the battery voltage.

If you have a PWM controller, you can do what you want as well, but for it to efficently capture the energy you should not let the voltage get too much above the battery voltage.

 

[MrNatural22]

Oops ??‍

 

[Guy]

What kind of solar controller do you have? If you have an MPPT controller, you can pretty much do what you want with the solar panels as long as the voltage from the panels is higher than the battery voltage.

If you have a PWM controller, you can do what you want as well, but for it to efficently capture the energy you should not let the voltage get too much above the battery voltage.

I am getting 2-100w panels and a EPevers 20amp MPPT controller. That controller says max watt imput is 260. That leaves me no room for another panel. If I get a Renogy PWM Wanderer 30 amp it can handle 400watt imput. Cheaper that MPPT enough that I can add another 100W panel later.

 

[MichaelK]

I am getting 2-100w panels and a EPevers 20amp MPPT controller. That controller says max watt imput is 260. That leaves me no room for another panel. If I get a Renogy PWM Wanderer 30 amp it can handle 400watt imput. Cheaper that MPPT enough that I can add another 100W panel later.

Can you change that order, or get an upgrade? I think it's a mistake to limit yourself to 20A. I would NOT recommend buying 12V panels either. Grid-tie panels are much cheaper, and a MPPT controller will transform the higher voltage down to what your battery wants. Although the MPPT controller is more expensive, 12V panels are more expensive still. You'll spend the least money with a 40A MPPT and grid-tie panels.

 

[Dzl]

The role of an MPPT controller (well, one role) is to take the high voltage of your PV array and convert it into the lower voltage of your battery bank. You can think of the PV and battery side of your controller as separate circuits with regards to voltage.

 

[Guy]

Can you change that order, or get an upgrade? I think it's a mistake to limit yourself to 20A. I would NOT recommend buying 12V panels either. Grid-tie panels are much cheaper, and a MPPT controller will transform the higher voltage down to what your battery wants. Although the MPPT controller is more expensive, 12V panels are more expensive still. You'll spend the least money with a 40A MPPT and grid-tie panels.

Where do you find these cheap Grid-Tie panels? All I've found are expensive systems for home owners etc. I can get 100W Mono panels for $64.00.

 

[MichaelK]

Craigslist and Ebay. Where are you located? The key here is local pickup, even with Ebay. It's not a one-time deal. Over the last 3 years I've made purchases that amounted to 2.7W/$, 3.3W/$, 4.5W/$ and 4.2W/$. These were all 1000-2000W purchases each, that I made for myself, and neighbors. Looks like your getting 1.6W/$.