# Diffferences between 12 & 24 Volt Solar



## KMA1 (Dec 9, 2006)

I need some help. I am totally new to solar, but looking at a small system. I have some questions :

1. What is the difference in battery requirements for 12 and 24 Volt system. Can I still use 6 and 12 volt batteries?

2. What about the charge controller and inverter? Any major cost differences?

3. Any reason to choose one (12 or 24 volt setup) over the other?

4. Any experiences or comments on Solar World SW265 panels?

5. Recommendations on equipment brands and models?

Thank you for any and all the help you can give me.

KMA1


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## biggkidd (Aug 16, 2012)

I'm not even gonna pretend to have all the answers. But I will say the higher voltage systems seem more efficient. Yes the 2, 6, and 12 volt batteries will work. Also higher voltages allow longer runs on smaller wire than lower voltages. So than can make quite a cost difference in setup cost.

Larry


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## Jim-mi (May 15, 2002)

Those SW 265's are very large panels . . .not easy to handle.
Those 60 cell panels are intended to be put in high voltage series strings.
High voltage DC is very dangerous . . . .You need experience to handle that voltage safely.
That high voltage needs to go into the more expensive controllers ..(6 to $700) if you are going with a 24v battery based system.
Over all those 265's are not really a good way for a beginner . . Unless . .you have some knowledgeable help.

Inverters . .You get what you pay for . . .the truck stop $100 stuff is junk...The Outback . .Magnum $2000 is the good stuff.


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## TnAndy (Sep 15, 2005)

KMA1 said:


> I need some help. I am totally new to solar, but *looking at a small system.*


What size system ? 

What do you plan to use it for ?  

Do you EVER plan to expand it significantly ?

Those need to be addressed before worrying about other questions.


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## KMA1 (Dec 9, 2006)

I am considering 5 panels to begin with. But I might expand to become more self-sufficient or even go off grid in the future. I was looking at running power to my shop from it. Also, if feasible possible putting freezer and refridge circuits on it in the house. I would pull whatever circuits I run in the house from grid and not hook up a grid tied system now. Our Electric Cooperative is dead set against solar net metering.

If this works well for me, then I might expand and go off grid altogether, or add additional solar only house circuits.

I am new to solar and DC electric, but I have basic AC wiring experience. Wired my own house among lots of other things.

Thanks for the responses so far. Looking forward to hearing more.


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## Nimrod (Jun 8, 2010)

The voltage that a bank of batteries puts out depends on how you wire them together.

If you wire 2 batteries of the same voltage in series it means that you wire the positive terminal on one to the negative terminal on the other and attach your load to the unused positive and negative terminals. If two batteries are wired in series their voltages add together. Two 6 volt batteries wired in series put out 12 volts. Two 12 volt batteries wired in series put out 24 volts. Think of a flashlight that uses 2 D cell batteries. Each battery puts out 1.5 volts. They are in series so the bulb gets 3 volts. 

If you wire 2 batteries of the same voltage in parallel it means that you wire the positive terminal of one to the positive terminal of the other and negative to negative too. To attach your load see the article on balancing below. Two batteries wired together put out the same voltage as one of them but you can store twice the electricity as one. Two 6 volt batteries wired in parallel put out 6 volts. Two 12 volt batteries put out 12 volts.

If you have 4 batteries of the same voltage you can really have some fun. If you wire all 4 in parallel the bank will put out the same voltage as what one would put out but you can store 4 times the electricity. If you wire all 4 in series the bank will put out 4 times the voltage as one of the batteries. If you wire 2 batteries in series with each other and the other 2 in series with each other and then wire the pairs in parallel you get twice the voltage as one battery.

Here is a link that shows pictures and explains.
http://www.solarray.com/TechGuides/WireDiagrams_T.php

This guy talks about balancing.
http://www.smartgauge.co.uk/batt_con.html 

The charge controller has to have enough capacity to handle the maximum output from your solar panel array. Many charge controllers can be set to charge several different voltage battery banks so you set it to charge the bank you put together. 

The inverter has to be big enough to handle the maximum load you put on it. Note that starting an electric motor can draw 2 to 3 times the amperage as it takes to run it. Many inverters put out modified sine wave electricity. This power may cause your electric motors to run hot and can damage sensitive electronics like your computer printer. Inverters that put out pure sine wave power are pricey but worth it if you need the clean electricity.

The higher your battery bank's voltage the smaller diameter wires you need to use to hook it up to your load. It can save you a lot of money.


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## topofmountain (Nov 1, 2013)

I'm just learning about solar & wind turbines. The first thing I was told by a company that sells the equipment that before I do anything I needed to fill out a load evaluation sheet to figure the amount of wattage I will use. If you have a power bill you can divide your wattage on your bill by 30 days to get your daily usage.

When I did mine it showed I use 1350w avg & 1830w max. So now I know I need a min. of a 2000w pure sine inverter. 
In the area I'm in it was figured that I needed 2-220w panels 
Most companies that sell solar & wind will help you by providing you with an estimate of equipment needed based off a load evaluation sheet. Mine was based off of using propane refrigerator. Which after more research have figured that added solar needed to run a refer was cheaper than propane.
Just what I have learned. I have been studying options for a few months now.


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## lynnemabry (Dec 28, 2013)

Ok, solar for the person that doesn't understand it and has to go with it works out like this.

First, change how you live.........
Second, we have panels in my case 6 (we had 7 but things happen) they make power and send it to the charge controller. Get the best you can afford. Match it to the largest size your system will ever be. The charge controller feeds the power to the batteries by deciding what the batteries need. So not to over charge your very expensive batteries. 

The batteries store the power and unless you use the first rule you will never have enough. Get big expensive batteries and take good care of them. And don't mix old and new ones. They don't like it.

The inverter takes the batteries and make 110v for the house. 12 or 24 I don't think was the big deal as long as the batteries are wired right. But, our 2000watt inverter just barely handles the fridge, freezer and washer. Peak load and all that. Do not try the microwave at the same time or you will be hitting reset. 

Most of this is just active participation in your power life. And the first rule. Only LED bulbs, almost no microwave, no vacuum, no blow dryer, heck no dryer, no big screen tv, nothing that makes heat. Most people are not prepared to make enough changes to be able to do it. And you can't just have it sitting there just in case. 

Good luck.


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## kycrawler (Sep 18, 2011)

If this is for a house that you intend to live in go48 volt and don't look back I thought I would be fine with 24 but now I have to either live with 24 or buy another expensive inverter and rewire everything and take a loss on the 24 volt inverter I bought


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## hickerbillywife (Feb 28, 2014)

Is there a particular brand of inverter that is best or any that I should stay away from.
I'd like the security of having a backup for a large freezer at the very least. I'd also like to get the right equipment the first time, meaning get as large a system as I can afford.
Hoping we could ad on as we go along. Would I be better off to get a solar freezer as to get a solar set up to run the freezer I already have.? It is only a couple of years old.


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## lynnemabry (Dec 28, 2013)

For an inverter I think as long as it is pure sine wave and a large enough total watts for all intended uses you are ok. I think we have xantrex. Also find a local company to deal with if possible. That way they can steer you toward parts that go with your system. 
It won't do any good to buy things online if you are not sure if it will go with your system. We paid a little more, but that way we get their knowledge too. 
A lot of people hodgepodge systems together and make it work but we wanted a power system not another project. My husband still had to have the skill to install it and needed to understand all the basics of working with electricity. (He is a mechanic.) 
We looked at fancy DC and propane appliances but found that putting money into a total system was more cost effective and more flexible. A solar freezer is only a freezer. Six grand in with a self install and we can power everything.


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## lynnemabry (Dec 28, 2013)

Also, most of it you can't buy as you go along. You will need it all in the beginning. Also you should not just keep adding batteries since mixing old and new is bad for some reason. (I don't need to know why, I leave that to my husband.)


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## hickerbillywife (Feb 28, 2014)

Thanks a lot. 6000 is not as bad as I thought.


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## kycrawler (Sep 18, 2011)

Outback inverte s are hard to beat. I still reccomend 48 volt.


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## Gray Wolf (Jan 25, 2013)

We run our place on 24 volts. There is no reason to go with 12 volt inverters these days.

We have had Trace and Magnum inverters. Magnum now but both good brands.

We have had Xantrex and Outback charge controllers. Outback now but both good.


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## Alaska (Jun 16, 2012)

I would start with contacting as many installers as you can find in your area. If you can find one that will speak english not just solar/computer jibberish and will work with you and your budget you will be way ahead of the game.
I have done a lot of stuff myself but now after finding a guy who I can work with I have him do more than me. Its nice to have someone to call if/when you have an issue.
WE have a 24v system. Started with the bergey XL1 because we overestimated our wind. Added 3 sw175 panels thinking the bergey controller would also handle them. After advice from a tech at bergey we added a outback fm 80 to handle the panels. First solar guy was an idiot put wrong ends on cables on one panel, no power. 
We abused our first set of trojan t105 batteries. 
6 years later in the morning we will connect panels 13 through 22 to our second fm 80 and our rolls batteries. 
We are totally of grid.
I would start off with a cheap set of batteries, maybe some sams club golf car. ruin them and learn before you invest in the big boys.


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