Off grid connection for a shed.

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Off grid connection for a shed.

Postby Grakat » Fri May 22, 2015 6:29 pm

Hello everybody,

I have just purchased 2.5 acres of land in the Hunter Valley, NSW on which I one day plan to build. Until such time as I am able to build the house I will be putting up a shed and converting part of it into a weekender. As such I would be interested in taking the shed off grid. This would serve two purposes. Firstly I would not need to connect to the grid and pay the connection fee for just a shed, but rather wait until the house is built. Secondly it would be a great opportunity to learn for when I do build the house, for I am interested in at least a hybrid system for the house.

The loads that I am considering running would be LED lights, a 12v fridge, which can also run on 230V, a small water pump (12v or 230v) and in the future maybe a small LED TV. The idea is to put a system together without it costing the earth to help me learn and fill a need.

I have seen what appears to be charge controller/inverters in one box, usually on eBay, which appear to take an input from a PV panel and charge a battery. These inverters appear to then supply 230v from them. However to get MPPT charging from them they usually start at 24v for the batteries.

What do you recommend the best way to go would be for this project. Would it be better to go for 24v or 48v in the batteries (which would cost more in batteries) or would it be more beneficial to go with 12v?

Regards
Graham
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Re: Off grid connection for a shed.

Postby davidg » Fri May 22, 2015 11:46 pm

Hi, welcome.

Most of the cheap "fleabay" all-in-ones are pretty horrible products in reality. They have disappointing results most of the time. Sorry to say. Off-grid and hybrid system is really a place where you only get what you pay for, so if its cheap it typically is crap.

The first question, how far is the Grid from your site and what voltage are the lines that are available?
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Re: Off grid connection for a shed.

Postby lantern » Sat May 23, 2015 9:20 am

Re the fridge do not get what is known as a three way one.
ie gas/ 240V/ 12/24V. It will use way too much power.
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Re: Off grid connection for a shed.

Postby Grakat » Sat May 23, 2015 3:16 pm

I already have a 12v compressor fridge. One is an ARB fridge, the other is a Waeco. Both are 50L and can run on 12v or 230v.

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Graham
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Re: Off grid connection for a shed.

Postby Grakat » Sun May 24, 2015 9:44 am

davidg wrote:Hi, welcome.

Most of the cheap "fleabay" all-in-ones are pretty horrible products in reality. They have disappointing results most of the time. Sorry to say. Off-grid and hybrid system is really a place where you only get what you pay for, so if its cheap it typically is crap.

The first question, how far is the Grid from your site and what voltage are the lines that are available?


Hello Davidg.

The power is three phase and available at the corner of the block. I don't want to connect to the grid until after the house is built. This could be a few years away. I don't want to dig 50m of trench under the potential house building site. In the future, as mentioned above, the shed could be a power shed feeding back to the house.

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Re: Off grid connection for a shed.

Postby davidg » Sun May 24, 2015 7:01 pm

Grakat wrote: power is three phase

What voltage? 3 phase is the standard for most transmission of grid power, the voltage however varies dramatically.

For instance we have 3 phase right outside our house here in dandenong the power lines are STD 400V LV power. The upper ones are 22kV.

The lines outside our farm are 33kV 3phase primary feeders to the next town down the road about 30km's from us. So if we wanted power from the grid then not only do I have to install under ground cabling but we also have to pay for transformer/substation as well, which adds another $25k on the cost according to ausnet services as they now want to be known (SP Ausnet)

Grakat wrote:I don't want to connect to the grid until after the house is built.

Sounds good to me.

Grakat wrote:I don't want to dig 50m of trench under the potential house building site. In the future, as mentioned above, the shed could be a power shed feeding back to the house.


If the intention is to connect to the grid, I suggest finding out to start off with the up front cost from the distributor. Once you have that then plan how power is going to ultimately be supplied, it would afterall be a cost that may need to be factored in or you may plan to be permanently off-grid from day one, keeping in mind that if you want a really decent off-grid system that behaves much like being on the grid budget around 40-50k installed.

For us with the transformer and the materials to get the power underground to house meant we had a good budget for going off-grid which we will, there's no benefit to being on grid for us. At about 40k for the underground materials I would have done the installation. The result a farm that will run permanently offgrid and that's way the budget has been planned, the house had some changes as well to reduce energy consumption considerably, such as substantially improved insulation for one, LED lighting throughout and a heating system of my own design based on hydronics leveraging excess PV power from the off-grid system, will still have a combustion heater as well but that should only because we want use it not because we need to.
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Re: Off grid connection for a shed.

Postby Tracker » Mon May 25, 2015 9:47 am

..
I agree with the presented comments..

If planning a system, then try to start with good components.. separate the charging and the power inverter.
See if you can find a second hand quality inverter on gumtree or ebay...

Definitely 48 or 24v at the minimum..

Providing led lighting is not an issue.. running the fridge will need some consideration of battery capacity ..
..
.
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Re: Off grid connection for a shed.

Postby Grakat » Mon May 25, 2015 5:36 pm

My apologies

The 3 phase is the smaller 400v connection, rather than the 22kv stuff. Namely it's the three phase that is fed directly to a house.

As mentioned above I will look at separating out the charging and inverter side to avoid the eBay rubbish. The fridge can run on 230v or 12v. However if I go to a 24v system my fridge won't like it unless I run on 230v AC.

LED lighting is definitely not a problem. I use it camping and have some already that is suitable. I am assuming 12v LED or are you suggesting 230v LED with the controllers like you find in LED Downlights?

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Graham
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Re: Off grid connection for a shed.

Postby Gordon-Loomberah » Mon May 25, 2015 6:30 pm

You can still run your 12V fridge at 12V if you use a DCtoDC converter between it and your battery. 24 or 48V is a much better option for your battery (26 or 52V if using LiFePO4). Brands like MeanWell produce good quality reliable gear.
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Re: Off grid connection for a shed.

Postby jules » Mon May 25, 2015 6:51 pm

If it helps in your decisions, there's plenty of good 24V DC LED lighting available.

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Spares; 5 x 12V, 1,000 Ah batteries plus a couple of regulators
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