250W Solar Panel 24v to 12v batteries

[skasambo]

Team

I have a solar panel of 250W , 24 V system. Again I have two batteries of 12v both at a capacity of 100Ah. All my bulbs and investor are 12v system. I keen to know which batteries configuration will help me to achieve maximum power. Series or Parallel? What are the advantages and disadvantages of each configuration?

Please assist.

[Amy@altE]

Are you saying the solar panel is 24V? Are you sure? What is the Voc on the specs, or how many cells (squares) does it have? If it has 60 cells, and a Voc of around 38V, it is a 20V solar panel and cannot be used to charge a 24V battery bank in hot weather. If it is 72 cells and Voc of around 44V, then it is a 24V solar panel and can charge a 24V battery.

However, since you have 12V loads, it makes sense to have a 12V battery bank, with the 2 batteries wired in parallel. Regardless of if you have a 20V or 24V solar panel, you will need an MPPT charge controller to charge it with a higher voltage solar panel. Outback Power has a 20A MPPT charge controller that would do it. SCCM20-100

[skasambo]

Thank, I meant 250W with almost 39W on measuring, however my system is 12v for bulb and investor. Kind need to know should the batteries be in series or should I make them on parallel. Which is the best practice and why?

[Amy@altE]

Wiring two 12V 100Ah batteries in parallel will result in a 12V 200Ah battery bank, which is what you need for your 12V load. Wiring them in series would result in 24V 100Ah, which is too high voltage for your loads. A solar panel that is almost 39V is a 20V solar panel, not a 24V and will not charge a 24V battery bank well in the heat when the voltage of silicon solar panels goes down. As I said, you need to wire the batteries in parallel with an MPPT charge controller to drop the voltage down and current up to charge the 12V battery bank.

[skasambo]

Some people say wiring two batteries in parrallel for 12v system from that solar panel which is 24 v system will let the the batteries not to charge..Is this theory correct??

[jflorey2]

Some people say wiring two batteries in parrallel for 12v system from that solar panel which is 24 v system will let the the batteries not to charge..Is this theory correct??

No. Certainly not ideal but the batteries will still charge.

[SunEagle]

Some people say wiring two batteries in parrallel for 12v system from that solar panel which is 24 v system will let the the batteries not to charge..Is this theory correct??

Actually it may be depending on the Charge controller.

It doesn't really matter if your panel voltage is much higher then your battery system. Your charge controller will regulate the output for the correct battery charging voltage.

The problem is trying to charge a 24 volt battery using lower voltage "12v battery panels". The only way to do that would be to wire at least two of those panels in Series to boost the voltage above the 15volts needed for charging.

Most people get all mixed up with battery voltage and panel voltage. The key is getting the correct Charge Controller to that will utilize as much of your panel wattage as possible and provide the proper charging volts & amps for your battery system.

[skasambo]

Guys, if i get you correct for my case i should rewire parrallel for my two battery 12v and my 250w solar panel 39w .I have charge controller of GP5024

[Amy@altE]

Guys, if i get you correct for my case i should rewire parallel for my two battery 12v and my 250w solar panel 39v .I have charge controller of GP5024

That is a PWM charge controller. You have to have the nominal voltage of the solar panel and the battery bank the same, or you will lose most of your power. Since you have a 20V solar panel and a 12V battery bank (once you rewire them), you cannot use that charge controller. You need an MPPT charge controller that will lower the voltage of the output of the panel and raise the output current.

[jflorey2]

Guys, if i get you correct for my case i should rewire parrallel for my two battery 12v and my 250w solar panel 39w .I have charge controller of GP5024

That will work but you will only get about 80 watts out of that panel. You will lose most of the power to the severe voltage mismatch, and the rest to the usual difference between STC output and real-world output. If you want to get more power out of the panel you'll need an MPPT charge controller.

[skasambo]

With MTTP,how much Watt will get

[skasambo]

Solar queen,what best configuration i can go with my system....rewire battery in 24 series battery bank and tap each battery for 12v load..say tap one battery for 12v invertor and other battery for 12v lamp??or how i should go with???

[LETitROLL]

rewire battery in 24 series battery bank and tap each battery for 12v load..say tap one battery for 12v invertor and other battery for 12v lamp??

NO, don't do that, Whenever you use 2 or more batteries, no matter which way you wire them it is VERY important to battery life for them to be equal and balanced, are you starting with 2 exact same batteries, same brand, same age, same amount of use each so far?

[skasambo]

LeTIrol
I understand you. Batteries are new and same brand...is that okay..or I will still kill them.From all above my concerns how best I can make my configuration you think

[LETitROLL]

LeTIrol
I understand you. Batteries are new and same brand...is that okay..or I will still kill them.From all above my concerns how best I can make my configuration you think

As jflorey said , parallel is not ideal, but it is okay, just keep the batteries as equal as possible (cables same size, type, length etc.) Series is much better, but you need 72 cell panels for best results with that (with your current batteries), and it does not sound like you have that (yours most likely 60 cell), unless you have 72 cell panels (42+ volts open circuit) then the best you can do with your system would be to get a "real MPPT" controller (not a cheap one) for maximum harvest and it will best regulate your panel to your 2 batteries in parallel, since you need 12v for your load(s)