Solar panel battery charging

[DAVE HEARSON]

Hello all
Could members who have knowledge of charging large banks of batterys please reply, I am going down the road of finding the best way to charge 12V 180AH batterys, this is for our farm house in Spain (off grid).
What I need to know is what size output do the solar panels need to be to give resonable charge to the batts?
The amount of time it takes to fully charge batterys via solar panels?
What are the best types of solar panels to do the job?
I do understand it would depend on the load on the batterys- the charge state-ect-ect
All I need is a rough idea where to start from.
The batterys are brand new items.
Regards Dave H.

 

[PV Martin]

Hi Dave,

Are you running a genny too as backup or is it purely going to rely on the PV?

 

[PV Martin]

how many batteries in the bank and how are they configured?

 

[DAVE HEARSON]

Hi Martin,
I have a genny as backup, which I am using to charge the batterys through the day for an hour or so, so that we have power at night time, we do not live in Spain but go there every two months or so, but think it would be better if the batterys were being in a state of charge all the time, regards Dave H.

 

[DAVE HEARSON]

Hi Martin
I have 2 banks of four, 1 bank of four = 48v to power a 48 volt ups
and 1 bank of four=12v which power low voltage lighting and anything else I can get hold of that runs on 12volt
regards Dave H

 

[PV Martin]

Dave,

i will have a chat with a guy i work with as he knows all about batteries charging/discharging etc he will know best. i will reply soon.

Cheers

 

[rose68889]

hi, we have the solar home system can produce up to 12V 200MH,if you are interested in it,
Then we will offer more details and best price to you,
looking forward to hear from you soon,
Best Regards,
Rose

 

[john999uk]

If you have a look at motorhome forums you might find some good info although they normally run 12v dc. They use a regulator between the solar panels and the batteries to ensure they are charged correctly. I believe you can now get regulators that take a higher voltage input and enable more of the power to go to the batteries, I think they are called MPPT regulators. Basically a 100watt solar panel can generate upto about 8amps. So if you get very good sunlight on a 100watt panel that is angled optimally you might get a total of 80amps in your battery on 10hrs of sun. Obviously you have to get good bright sun otherwise the output will be lower.
You say you are using 4 batteries to create 48v to run a ups. If you are running a ups as a 240v power 'transformer' it might not be great efficiency wise. A ups is normally designed to keep computers running during a power out. I would suggest you look at inverters. They tend to be more efficient at converting 12vdc to 230vac. It also makes it more simple just having a 12v battery system rather that 1 x 12v system and 1 x 48v system.
Hope that gives you a few clues.

 

[Maisie Bolton]

The point is any storage battery (accumulator if you are English) slowly goes dead. With a 12V (okay 13.8V+) solar pannel attached across the terminals even 25 mA for 8 hours a day cancels out the slow discharge and maybe even adds a little charge.

Ask your local VW dealer if he has a few small pannels that he would sell you.

 

[Worcester]

Check out the SMA Off-grid Solutions - Sunny Island SUNNY ISLAND 6.0H / 8.0H and a normal SMA PV inverter.

Sunny Island controls the battery charging / conversion to AC and automatically kicks in the Genny when needed.

Batteries are usually made up from 2V cells.