# Solar panel charging my batterys



## smitty32303 (Jan 30, 2010)

New to solar. I have eight 6v golf cart batteries. each are 221 ah. Set up as a 12v output. I want to find out how many watts of solar panels it will take to recharge this battery bank over the course of a days sun light. Can anyone walk me threw the formula. I only want it for an emergency power supply and running a 2500 w inverter during black outs for basic lights, Radio, and such, but on heavy use, would like to know I have enough charging power to recharge it quickly.


----------



## bunkerbob (Sep 29, 2009)

smitty32303 said:


> New to solar. I have eight 6v golf cart batteries. each are 221 ah. Set up as a 12v output. I want to find out how many watts of solar panels it will take to recharge this battery bank over the course of a days sun light. Can anyone walk me threw the formula. I only want it for an emergency power supply and running a 2500 w inverter during black outs for basic lights, Radio, and such, but on heavy use, would like to know I have enough charging power to recharge it quickly.


Here is one of the tools I use on my system... http://www.outbackpower.com/resources/string_sizing_tool/

My system consists of 24 panels, two charge controllers, two inverters, 36 T-105 batteries, 10 AGM batteries. This runs a normal 2200sf house for about 2 days with limited(cloudy) sunlight, with full sun runs everything and charges the batteries in about 1 day.


----------



## mosquitomountainman (Jan 25, 2010)

bunkerbob said:


> Here is one of the tools I use on my system... http://www.outbackpower.com/resources/string_sizing_tool/
> 
> My system consists of 24 panels, two charge controllers, two inverters, 36 T-105 batteries, 10 AGM batteries. This runs a normal 2200sf house for about 2 days with limited(cloudy) sunlight, with full sun runs everything and charges the batteries in about 1 day.


What kind of charge controllers do you have?

Steve


----------



## bunkerbob (Sep 29, 2009)

mosquitomountainman said:


> What kind of charge controllers do you have?
> 
> Steve


Outback, one MX60 and the other a Flex80, split the panels between them.

BB


----------



## tnelsonfla (Feb 24, 2012)

*Solar power*

I just this year started playing around with solar panels and such. There is alot to learn. The good thing is from what I've seen there seems to be a "right" way to do most solar & wind systems. The guess work seems to be done once you know what you want to run.


----------



## mosquitomountainman (Jan 25, 2010)

bunkerbob said:


> Outback, one MX60 and the other a Flex80, split the panels between them.
> 
> BB


Thanks. Been thinking of going to Outback next time we upgrade.


----------



## trkarl (Jun 16, 2010)

bunkerbob said:


> Outback, one MX60 and the other a Flex80, split the panels between them.
> 
> BB


Exactly how I had mine set up but the fan on my MX60 finally died. That was a good excuse to get a new cc. Now I have a Midnite Solar Classic 150 in it's place.

So far I prefer the simplicity of the Outback CCs.


----------



## bunkerbob (Sep 29, 2009)

trkarl said:


> Exactly how I had mine set up but the fan on my MX60 finally died. That was a good excuse to get a new cc. Now I have a Midnite Solar Classic 150 in it's place.
> 
> So far I prefer the simplicity of the Outback CCs.


My fan also died, they covered mine, the first generation of fans were defective, contact them for replacement. The Flex80 has two now.

BB


----------



## Tex (Oct 31, 2008)

Your golf cart batteries are set for 12V @ 884AH. That is roughly 12x884=10608Watts. If you divide that by the number of sunlight hours in a day, that will tell you how many watts worth of solar panels you will need. That number varies throughout the year. You may have to consider the humidity and cloud cover, as that takes away some of your usable sunlight. For that much expense, I would add a good charge controller and an inverter for everyday use. That's the only way you will get your money's worth.

You may want to rewire the batteries for 24VDC or even 48VDC to minimize line losses.


----------



## bunkerbob (Sep 29, 2009)

Tex said:


> Your golf cart batteries are set for 12V @ 884AH. That is roughly 12x884=10608Watts. If you divide that by the number of sunlight hours in a day, that will tell you how many watts worth of solar panels you will need. That number varies throughout the year. You may have to consider the humidity and cloud cover, as that takes away some of your usable sunlight. For that much expense, I would add a good charge controller and an inverter for everyday use. That's the only way you will get your money's worth.
> 
> You may want to rewire the batteries for 24VDC or even 48VDC to minimize line losses.


 I've wired mine for 24vdc...


----------



## Tex (Oct 31, 2008)

bunkerbob - Those C&D batteries on the floor look very familiar. I'd guess 7 year old UPS12-270FRs.

Are you grid-intertied or stand alone?

Is your battery system grounded to the rack? I never see that on the UPS systems that I work on, but it makes sense when your system is modular with charge controllers, inverters, etc....


----------



## bunkerbob (Sep 29, 2009)

Tex said:


> bunkerbob - Those C&D batteries on the floor look very familiar. I'd guess 7 year old UPS12-270FRs.
> 
> Are you grid-intertied or stand alone?
> 
> Is your battery system grounded to the rack? I never see that on the UPS systems that I work on, but it makes sense when your system is modular with charge controllers, inverters, etc....


 Good call on the batteries and yes they are about that old, my wife's company was dumping them and I helped helped out disposing of 25. They still work great, by the way, I have another bank in the 'pit'.
We are off-grid. And yes I grounded the rack, makes the wire run shorter, it is then grounded to a UFER in the concrete.


----------



## Tex (Oct 31, 2008)

They quit making those batteries about 6 years ago and went to an internal post. I'm surprised that they still have a Liebert/Emerson AP340 UPS. (Tan unit with red led display and a rotary switch) They are about the only unit with a 340VDC bus. Good units. When I'm ready to build, the batteries will be cheap as I can sometimes get them for free.  They are going for $.30/lb for scrap when you are done with them.


----------

