I've fallen into the solar arena

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I've fallen into the solar arena

Postby crazyk » Sun Jun 29, 2014 8:33 am

Hey all. This is my first post so go easy!! And my electrical knowledge for acronyms is quite slim.

Where I'm currently living we are consuming an average of around 10Kwh/day running the house with a wife that likes to light it up like a Christmas tree.... Let's no go there.

I'm building a new house and was toying with the idea of putting solar at some point in time. I have approx 70m2 (I think) of North facing roofing available to install panels.
The major difference will be that there I'll be installing a 20KW ducted AC 3Phase unit. So don't know how much juice we will use from that.

Q1. I would most likely have to put a grid connect system in, but could I also have the battery bank? So that during the day I would produce and consume then at night consume from the batteries and if needed switch to grid ( say if the AC is running)

Q2. Also it just so happens that I scored myself around 40pcs of Brand New 12v 100ah Narada Polymer Gel batteries (and no they are not stolen) and I'm not sure if I should hold onto them or get rid of them because by the time I use them they will be getting old and also a 48V 1000w pure sine wave inverter.

Q3. If I did install the battery bank it would be approx 30-40m from my solar panels. Could this be a problem?

Anyway it's all probably a bit heavy for a first post so I'm eager to see the responses.
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Re: I've fallen into the solar arena

Postby Gordon-Loomberah » Sun Jun 29, 2014 9:21 am

Welcome to the Energy Matters Forums Crazyk :)

1: Yes you can use batteries in a hybrid system

2: They are the wrong batteries for your hybrid system, sell them if you can. For anything other than small portable camping systems, 12V batteries are a poor choice. You should consider a Lithium battery if you want to set up a hybrid system. There is lots of info on the forum about LiFePO4 cells, and hybrid systems.

3:Not really a problem, you just have to use suitably sized cables for the current
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Re: I've fallen into the solar arena

Postby bpratt » Sun Jun 29, 2014 9:27 am

crazyk wrote:Q3. If I did install the battery bank it would be approx 30-40m from my solar panels. Could this be a problem?


Welcome to the forums here crazyk !

As already mentioned, as long as the cables are thick enough it shouldn't be a problem. All the more reason to be on a 48v battery bank, as the cables required for a 12v system would be as thick as godzilla's tail by comparison ! :)
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Re: I've fallen into the solar arena

Postby crazyk » Sun Jun 29, 2014 9:40 am

I hear and read a lot of folk using 12v batteries. Without sounding ignorant , why would they be the wrong choice?

I thought from the research I've done that I would just configure them into a 48v system.

I have seen a lot of recommendations to use 6v also.

Lithium is an option if the numbers stack up.
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Re: I've fallen into the solar arena

Postby bpratt » Sun Jun 29, 2014 10:40 am

crazyk wrote:I hear and read a lot of folk using 12v batteries. Without sounding ignorant , why would they be the wrong choice?

I thought from the research I've done that I would just configure them into a 48v system.

I have seen a lot of recommendations to use 6v also.

Lithium is an option if the numbers stack up.


12 volt batteries have the issue of needing much larger cabling to handle the currrent being dragged through them, than say a 48v system, which is pretty much the standard voltage on a offgrid/hybrid system these days.

Bundling your standard 12v (multiple cell) lead acid/gel battery in series to get 24 or 48v is very difficult to cleanly and properly do to give the battery bank a good reliable life.

The better way is to have the capacity in individual cells joined together in series.

Lithium Iron Phosphate (LiFePO4) is the current technology gaining a lot of popularity, as it can be drained down lower than lead acid batteries by quite a margin, and still not lose a long life, where lead acid will drastically shorten their life if you take them down too far. As you can discharge lifepo4 much lower, you won't need to have as big a battery bank as you would with lead acid.
Kaco 6600
26 x Trina Honey 250w panels. (wish I could work out how to upload to pvoutput.org)

New house build :-
http://bandlnewhomebuild.blogspot.com

My weather station :-
http://jimboombaweather.com
bpratt
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Re: I've fallen into the solar arena

Postby crazyk » Sun Jun 29, 2014 10:55 am

Thanks BP

I think I'll try to sell them and later invest in Lithium.
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Re: I've fallen into the solar arena

Postby Gordon-Loomberah » Sun Jun 29, 2014 10:58 am

Have a read of this thread for a comparison between Pb-acid and Lithium battery performance: solar-wind-gear/topic5108-60.html

Using 12V batteries maximises the number of cells you need to make up a large battery - the more cells you have, particularly when in parallel, the greater the chances of having a problem. The aim is to use the minimum number of cells. With paralleled batteries, especially ones where you can't measure Specific Gravities, a bad cell is just about impossible to detect before it has started affecting other individual batteries, which leads to a shorter battery life overall.
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Re: I've fallen into the solar arena

Postby crazyk » Sun Jun 29, 2014 11:23 am

Thanks will read into that to get a better understanding.

BTW I have polymer gel batts
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