24v from panels stepped down to 12v

[jimmyh]

My inverter is 12v, my water pump is 12v. With that said, kinda need ultimately a 12v supply. Batteries can be configured any wich way (8, 6v)

I have a Xantrex C40. Can I input 24v to controller and output 12v? Or use something to step down volts after controller, or after battery bank?

My panel to controller run is about 40ft, a bit worried about loss and the need for larger gauge with the 12v from panels.

[SunEagle]

My inverter is 12v, my water pump is 12v. With that said, kinda need ultimately a 12v supply. Batteries can be configured any wich way (8, 6v)

I have a Xantrex C40. Can I input 24v to controller and output 12v? Or use something to step down volts after controller, or after battery bank?

My panel to controller run is about 40ft, a bit worried about loss and the need for larger gauge with the 12v from panels.

First off the Xantrex C40 can accept up to 125vdc input from the panels and charge a 12volt battery. So depending on what your pv panel specs are and how many you have will determine how they can be wired.

With the higher input voltage your wire size can be calculated based on that 40ft run.

The battery system will depend on your pump wattage and starting spec. Without that info it would be very hard to size them for your needs.

[Naptown]

What and how many panels
Please give spec's
You can use it but will require expensive 12 v panels.
Otherwise you will lose a large portion of the output as that is a own controller and to use higher voltage panels you would need to go to an mppt controller.

[jimmyh]

First off the Xantrex C40 can accept up to 125vdc input from the panels and charge a 12volt battery. So depending on what your pv panel specs are and how many you have will determine how they can be wired.

With the higher input voltage your wire size can be calculated based on that 40ft run.

The battery system will depend on your pump wattage and starting spec. Without that info it would be very hard to size them for your needs.

Excellent. So I can run my panels in at 24v and set the C40 jumper to 12v output. That sounds perfect.

[jimmyh]

What and how many panels
Please give spec's
You can use it but will require expensive 12 v panels.
Otherwise you will lose a large portion of the output as that is a own controller and to use higher voltage panels you would need to go to an mppt controller.

I have several 12v panels that I currently run in parallel that I could easily wire in series to 24v. With 24v I could run smaller AWG with less loss.

[SunEagle]

Excellent. So I can run my panels in at 24v and set the C40 jumper to 12v output. That sounds perfect.

First off you did not read my entire post.

Second off, I am not sure what you mean by "run my panels in at 24v".

If you have two "12volt" panels wiring them in series gets you about 35V (Vmp ~ 17.5v) not 24volts

So what are your panels rated and how many are you going to use?

[sdold]

His controller is PWN, so shouldn't he be running all panels in parallel? With two panels in series he's only going to get maybe 30% of the array's STC power.

[jimmyh]

First off you did not read my entire post.

Second off, I am not sure what you mean by "run my panels in at 24v".

If you have two "12volt" panels wiring them in series gets you about 35V (Vmp ~ 17.5v) not 24volts

So what are your panels rated and how many are you going to use?

I did read your entire post. All I really needed to know you answered. Thank you and have a great day.

[SunEagle]

His controller is PWN, so shouldn't he be running all panels in parallel? With two panels in series he's only going to get maybe 30% of the array's STC power.

Yes.

With a PWM CC the highest output would be to run all the panels in parallel. That gets you the most charging amperage.

Although depending on what he needs to charge his battery sometimes going with the higher input voltage (panels in series) and lower amps allows the use of smaller wire which could be less costly then what is lost in charging amps.

You almost have to do the math for each system depending on; wire run distances, battery Ah rating and panel specs. Cerainly using more than 200 watts should make you consider a MPPT CC again depending on the end result that you need.

[SunEagle]

I did read your entire post. All I really needed to know you answered. Thank you and have a great day.

But what you haven't told us in this thread is that you want to convert your 8 x 6v 12volt 1740Ah battery system into a 24volt 870Ah system.

Wiring those panels in series using a PWM CC will not get you enough charging amps. And depending on what your panels are rated I am not sure if wiring them in parallel would be enough since you only have a 40A CC and a very big battery system.

So what does you final solar / battery system look like and what are the specs of your panels?

[Naptown]

Excellent. So I can run my panels in at 24v and set the C40 jumper to 12v output. That sounds perfect.

Yes you can do that but you will lose 1/2 of the power your panels produce.
That controller is not designed to step down the voltage efficiently.
To do that you would need to replace the cc with an mppt or wire the panels in parallel.

[Amy@altE]

My inverter is 12v, my water pump is 12v. With that said, kinda need ultimately a 12v supply. Batteries can be configured any wich way (8, 6v)

I have a Xantrex C40. Can I input 24v to controller and output 12v? Or use something to step down volts after controller, or after battery bank?

My panel to controller run is about 40ft, a bit worried about loss and the need for larger gauge with the 12v from panels.

I think you need to be more specific about your panels. Some people here are reading 24V as actual measured output (Voc) and some, like myself are reading as nominal. What panels do you have? I'm guessing they are 36 cell panels with a Voc of about 22V. What wattage and what Isc (short circuit current) are they rated at?

The C40 charge controller is PWM, which means to not lose 1/2 of your power, you need to wire the panels at 12V, so in parallel for a 12V battery bank for your 12V loads. If you wire them in series for 24V and run it through the charge controller to a 12V battery bank, you will lose half of your power, which defeats the whole purpose. TO run them at 24V into a 12V battery bank, you need an MPPT charge controller.

[jimmyh]

Actual bank is 240amp x 8 = 1120, not 1740. image is example, Array is currently wired in parallel 12v.

Panel specs: (4) 100 watt 12v. Max volts: 17.4 Max amps: 5.75

Just trying to figure out if it is worth going to 24v on panel wiring or just keeping it at 12v. It has worked flawlessly for 3 years with a cheapo controller, but I am upgrading to the Xantrex C40 and a better pure sine wave inverter. The old wiring was so mickey mouse that I fried the inverter when trying to move my water pump....don't ask!

This is in a beach house in Mexico that gets uses 1x per month for 5 days. Since weather is an issue I like having a larger bank as security in case of poor charging days with rain and cloud cover.

[Naptown]

That controller you bought will lose half the panel power if you re wire in series for 24 volt to feed a 12 volt battery.
Keep panels in parallel with that new controller. When your inverter fries from old age then consider going to a 24 volt system. For now just replace the controller and leave everything else as is

[Amy@altE]

That controller you bought will lose half the panel power if you re wire in series for 24 volt to feed a 12 volt battery.
Keep panels in parallel with that new controller. When your inverter fries from old age then consider going to a 24 volt system. For now just replace the controller and leave everything else as is

Yup, what he said ^