Solar Energy Storage

Solar, wind, hydro and other non-fossil sources of electricity.
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Speedracer
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Solar Energy Storage

Post by Speedracer » Feb 02, 2014 6:46 pm

Hi All,

I'm thinking of building some type of energy storage for my solar system. Heres what I have planned...
using 20 12v 250AH deep cycle batteries in series to provide 240v
Mains connected directly to the batterys
1 charger connected to the solar system with a timer system to charge batteries during the day
1 charger with a relay system that when the battery bank goes below a certain output, it will charge off the mains.

From what I have worked out, I could build something like this for around the $8500 mark. I have been quoted close to $25k for a similar system.

Has anyone else done anything like this and care to share your thoughts?

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Dauntless
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Re: Solar Energy Storage

Post by Dauntless » Feb 02, 2014 7:15 pm

I have high hopes for sulfur/sodium, apparently already on the market and in use for power backup. But I'm not aware of a good link to help you get started.

http://www.extremetech.com/extreme/1575 ... ithium-ion
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Re: Solar Energy Storage

Post by amberwolf » Feb 02, 2014 7:33 pm

Speedracer wrote:using 20 12v 250AH deep cycle batteries in series to provide 240v
Mains connected directly to the batterys
That should be interesting, unless y'all have DC for your mains instead of AC. ;)

I think you're gonna need a rectifier and current limiter, and something to cut off charge once the batteries are full--something that checks *each battery* for it's voltage, not just the top of the stack, cuz otherwise when a cell or more fails, and it still tries to charge it all up, something may fail in a way you don't want.

I presume that the below:
1 charger with a relay system that when the battery bank goes below a certain output, it will charge off the mains.
is intended to do at least hte most important part of what I describe, but just in case, I thought I'd better point that out. ;)

Speedracer
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Re: Solar Energy Storage

Post by Speedracer » Feb 03, 2014 5:05 pm

Dauntless wrote:I have high hopes for sulfur/sodium, apparently already on the market and in use for power backup. But I'm not aware of a good link to help you get started.

http://www.extremetech.com/extreme/1575 ... ithium-ion

Nice one, ill have to look into this. Thanks :)

Speedracer
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Re: Solar Energy Storage

Post by Speedracer » Feb 03, 2014 5:18 pm

amberwolf wrote:
Speedracer wrote:using 20 12v 250AH deep cycle batteries in series to provide 240v
Mains connected directly to the batterys
That should be interesting, unless y'all have DC for your mains instead of AC. ;)

I think you're gonna need a rectifier and current limiter, and something to cut off charge once the batteries are full--something that checks *each battery* for it's voltage, not just the top of the stack, cuz otherwise when a cell or more fails, and it still tries to charge it all up, something may fail in a way you don't want.

I presume that the below:
1 charger with a relay system that when the battery bank goes below a certain output, it will charge off the mains.
is intended to do at least hte most important part of what I describe, but just in case, I thought I'd better point that out. ;)
Lol yes very valid points.. such as a dc to ac inverter, i forgot to add that to the list. If i use an inverter, i could use use batteries with a smaller AH rating and bind them in parallel as opposed to series and utilise the storage.. so very good point.. I saw they have 240v 3.5kw inverters on ebay for $339 (with some interesting photos on the ad http://www.ebay.com.au/itm/3500w-Power- ... 4897.l4275 )which is cheaper than the batteries and I could run a couple to supply different areas of the house.

The charger system is the key, I'm not too sure on how to build the solar charger to balance across the batteries but it wouldnt be too hard. The whole concept is feasible and will need a bit of tweaking.

I have learnt my electricity company apparently doesn't credit back the power you put in, only charge for the power you take out (according to their overseas call center). Therefore I'm still getting bills for the nightly use. :/

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granolaboy
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Re: Solar Energy Storage

Post by granolaboy » Feb 03, 2014 6:08 pm

Speedracer wrote:20 12v 250AH deep cycle batteries in series to provide 240v
Most solar setups are 24v. Maybe hook em up as 2s10p?
2010 EVT 168 @ 69v

Speedracer
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Re: Solar Energy Storage

Post by Speedracer » Feb 03, 2014 6:10 pm

granolaboy wrote:
Speedracer wrote:20 12v 250AH deep cycle batteries in series to provide 240v
Most solar setups are 24v. Maybe hook em up as 2s10p?
good call. Thanks

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Re: Solar Energy Storage

Post by Samd » Feb 03, 2014 6:17 pm

Many off grid houses stay 12 volt DC and forget the invertor.

12v lighting, 12v camping fridge (there are some nice units on ebay these days), 12v television. And just use small invertors for any items that are an exception. You can run your laptop charger with a car adapter...
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Speedracer
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Re: Solar Energy Storage

Post by Speedracer » Feb 03, 2014 10:09 pm

Yeah im not exactly off grid though as I live 5mins from the CBD. Plus I would like the flexibility of pluggin in whatever I like without worrying if its too much load or oops i need another plug in inverter, it sucks even trying to find an unused extension board in my place lol..

John in CR
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Re: Solar Energy Storage

Post by John in CR » Feb 09, 2014 3:49 pm

Instead of having all that electrical storage just sitting there, I'd much rather have most of my storage in some kind of vehicle. Of course that works best when you have a vehicle that's typically at home during peak sun hours, but at the kind of costs you're talking about I'd look toward an extra vehicle. I'm not talking about just using the solar to charge the vehicle, but also to have the battery pack in the vehicle supplying electricity to the house when the sun is off peak.

20x12Vx250ah is 60kwh, though with lead you're looking at more like 40kwh or so. How much solar power do you have in panels? I take it that you have a grid tie now. How many kwh are you feeding back into the grid each month?

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Re: Solar Energy Storage

Post by LockH » Feb 09, 2014 4:06 pm

Ummm... Perhaps see also the ES thread "Stationary lead-acid batt cases", here:
https://endless-sphere.com/forums/vi ... 14&t=57046

So, multiple 2V batts in series/parallel, and combo wind/solar energy generation.
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Re: Solar Energy Storage

Post by veloman » Feb 11, 2014 2:08 pm

I have two main ebikes, so I can always have one solar charging while out on the other. One bike uses a battery that is 3 different chemistries cobbled together for 50v 15ah. Part old lifepo4, part really old milkwakee tool packs, part laptop lico, part Currie lithium ebike battery.

It's great having two bikes/batteries always ready to ride. I didn't spend much money on them either. Under 2k total.
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LockH
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Re: Solar Energy Storage

Post by LockH » Feb 11, 2014 2:19 pm

"... always have one solar charging while out on the other."

Ummm... EVen when Planet Dirt spins around, enough that the sun appears to "drop below the horizon"??? Ya might want to add "wind" generation (the "wind", created by sunlight creating atmospheric areas of diff "pressure", tends to flow ("blow") better "at night").
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Kmob1
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Re: Solar Energy Storage

Post by Kmob1 » Apr 03, 2014 6:36 pm

Interesting discussion, I'd like to hear from anyone in Australia who has such an off grid system up and running

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Re: Solar Energy Storage

Post by Hwy89 » Apr 03, 2014 7:39 pm

Solar charge controllers are fairly inexpensive and do a good job of taking care of the battery bank. On the output side of the battery bank a good quality inverter charger in 12, 24, or 48 volt will provide 120 or 240 volt AC which is much easier and cheaper to distribute. Put in an approved transfer switch and wire into your existing panel and you can utilize your solar when it is available or switch to commercial power when it isn't.
I recommend you read up on solar power systems and talk to some solar installers before you commit yourself to a system.

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Re: Solar Energy Storage

Post by Hwy89 » Apr 03, 2014 7:49 pm

Take a look at my home built solar trailer at http://www.rimstar.org/renewnrg/mobile_ ... system.htm
There is a diagram of how all the parts are wired together

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Re: Solar Energy Storage

Post by cycleops612 » May 15, 2017 4:40 pm

Thing is, its often forgotten, that a stationary battery is a whole other debate to the usual ev context.

Weight, & sometime space, is irrelevant. there is no need for expensive light cutting edge stuff. The tesla 18650 power wall seems stupid to me.

As well as charge, why not also hunt up suitable daytime power consuming domestic jobs, and power them direct.

For much of the year e.g., when the sun is shining, the fridge and freezer are busy. If a mildly smart fridge/freezer could set its min temp say 10C lower when pv output suffices, and switch to solar power, then you have done useful work w/o the waste and cost of storing the power first - by over cooling ( within recommended ranges), you have stored solar power using the fridge/freezer~. add bladders of water to u freezer for extra power storage~ - a cool sink. Maybe the post breakfast dishwasher cycle?

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Re: Solar Energy Storage

Post by craneplaneguy » May 16, 2017 9:19 am

Not really relevant, but after 28 years off grid, now 10 grid tied, I remain very happy to have gotten the hell away from the large battery systems required for any significant home energy storage. I am lucky of course to have a utility that acts as my battery, 1 watt in, 1 watt out. Infinite size, no maintenance, and 100% efficiency with no standby losses! I still have to laugh, when on a sunny summer day I throw clothes in the electric dryer because it's easier and quicker then hanging them on a clothes line, I mean is that the height of energy inefficiency or what :shock: But I make it faster then I can use it, so screw it.

As to battery bank voltage, the last several off grid systems I've set up for others have all been 48 VDC. With almost all loads ran through a modern sine wave inverter charger. Simple and effective, and then you can use any consumer type 120 VAC blender, coffee maker or other small appliance. Paying more for a specialized lesser featured 12 VDC thingie just to "keep it simple", is tripping over a dollar to save a dime. 30 years ago it was the way maybe, not now with cheap PV and modern inverters.

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Re: Solar Energy Storage

Post by Hillhater » May 16, 2017 5:02 pm

CPG... i suspect you are more fortunate than most to be able to get grid storage without a significant cost penalty. :)
And I get the idea of using common 120v appliances with an inverter from a 48v storage, ...
But is it practical to run a storage system with dual 120v AC, and 12/24v DC outputs ?
Im thinking that for low power systems such as lighting (LED these days) , bore water pumps, Ebike chargers, USB chargers, etc ,...it could be more efficient running direct from DC rather than the "double switch" of the inverters if used from the AC supply ?..and avoids the need for all those nasty little electronic transformars at each lighing point !
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mxer
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Re: Solar Energy Storage

Post by mxer » Jun 23, 2017 7:14 pm

I ran a 12/24v dc lightning usb had some great results, you'll be amazed of what runs on DC voltage nowadays.

https://youtu.be/esg3N9mfNHY

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Re: Solar Energy Storage

Post by Hillhater » Jul 04, 2017 3:52 pm

With the present cost of domestic solar panel systems so low ( and going lower ?) , i cannot see a battery storage system making sense if grid connection is available..
Note:.. i am referring to Australia primarily...YMMD.
For $3000 i can get a 5 kW system installed. ( tier 1 panels , 10 year warranty, etc etc)
That should generate 25-30 kWh per day
Currently I use 12kWh per day month (average) , and pay $0.25 per kWh flat rate, from the grid. ( =$3.0 per day)
i can get $0.09 -$0.15 per kWh back from the power company for the surplus power i feed back into the grid.
So say i use 6kwh in house, during sunlight time, and feed back the surplus 19-24kwh , ( earning between $1.70 -$3.60 per day) ...which even at the minimum $1.70 is more than enough to buy back the 6kwh needed to get through the "no sunlight" hours !
That means i have eliminated my $3.0 per day power bill, which pays off the cost of the solar in under 3 years !
why would i spend an extra $10k to have a 10kWh battery installed ? ( needing a 12 year payback !)
Am i missing something ? , im sure its not all roses, but i do not see a case for a battery here.
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Re: Solar Energy Storage

Post by LockH » Jul 04, 2017 11:10 pm

To OP "Speedracer"... Can't recall you mentioned your location? But MY fave "battery" involves "pumped hydro". In other words you use solar-etc generated electricity to store "energy" "up hill"/against gravity. Then use the liquid (eg water) flowing back down hill to run a generator. So horribly "lossy"/inefficient... but with near zero costs to generate to start with. :wink: "Large scale" involves lakes and rivers... (and generators) but "smaller scale" might employ water storage tanks in the attic and pipes (and a generator)? Water pumped "up" will involve electricity "generated" by solar (cells/"panels") or "winds". So. Beyond chemical cells ("batteries")... watts up re your location?
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