Solar Powered Shed

With the stables fit out finished it was time to finish off the solar power project for the shed. This is our first foray into solar power so we started small, modular and scalable. We really just wanted the ability to run lights and the occasional small appliance (like horse clippers) from the 3-bay shed. It’s about 40m from the house so it wasn’t worth the effort and disruption of digging cable from the house.

The panel on the roof of the shed is just 10w – enough to trickle charge a battery. I’d calculated our use to be fairly small, and with a reasonable capacity battery, there was no need to charge it any faster than 10w. That said, there is room on the roof stand to mount another panel in future if we need more power. The panel is incredibly effective and even produces power on an overcast, showery day.

The panel faces North and is set at an angle of 42 degrees. Interestingly, the optimal angle to maximise your solar absorption is the same as your latitude – in our case 42 degrees.

The battery and charge regulator are the smallest capacity I could find, but still with some room for expansion. The setup is pretty straightforward – energy comes from the panel into the regulator and then to the battery. The battery is wired to a switch to control the lights.

With such a small solar panel, a charge regulator isn’t strictly required as it would be almost impossible to overcharge the battery, but I never miss a chance to buy a box with blinky lights on it…and we can add more panels in future without worrying about cooking the battery. When the battery is full, the regulator stops charging it.

The battery is a bog standard car battery. You can spend a fortune on deep-cycle batteries, designed to discharge and recharge many times over, but as our battery will never be less than around 95% charged, a cheaper car battery is fine. It has a capacity of 32AH (or approximately 1 amp of current draw for 32 hours).

I’ve used standard TPS house wire for all the wiring and it seems to work fine (although it might be slightly less efficient). With 12V systems you want to use the thickest gauge wire you can, but we’re dealing with short distances (and I happened to have a roll of house cable lying around).

The lights are 12v LED spots with 48 white LEDs in each cluster. They draw 1w of power and put out a lot of light for their size. Three of these at the front of the stall allow more than enough illumination to change a bandage, feed the calves etc. Now that I’ve tested them, I’ll put another strip of three in the middle of each stall.

The inverter is a cheapie from Dick Smith. It is only 300w so it will run a 240V radio, clippers etc. We could replace it in the future with something more substantial if we needed to use power tools out there for example.

Finally, a nice chunky waterproof swith to control all that solar power.

Future plans for the shed include 12v sensor lights and possibly a small wireless repeater to extend the farm wi-fi network, but that’s definitely for another day…


9 Comments »

  1. Rob Says :
    1 October, 2008 at 10:55 am


    Nice work! :)
    Remote farm cams coming soon?

  2. John Says :
    1 October, 2008 at 11:20 am


    You’d better ask she-who-controls-the-to-do-list on that one :)

  3. Robin Says :
    1 October, 2008 at 11:27 am


    Wow – wish my todo list contained that job. Nice one John! What was the total cost of the project if you don’t mind me asking?

  4. John Says :
    1 October, 2008 at 3:57 pm


    From memory (bought the bits over several months)

    10W Solar Panel from DSE – $120
    Mounting Frame for Panel from TradeMe – $50
    5A Solar Charge Controller from TradeMe – $50
    Battery from Repco – $80ish
    LED Bulbs from TradeMe – $15 each
    Switch from Trademe – $30ish
    I already had the inverter so didn’t include that (about $120)

    All up about $400ish – so not too bad for a first foray (and everything is reusable as I upgrade bits and pieces)

  5. Peter Says :
    8 October, 2008 at 12:18 pm


    This is a most useful posting and one that I will getiing my son onto (our electrician).
    We have just purchased a small holding (1 1/2 acres) between Carterton & Greytown on the Matarawa Road.
    http://www.kiwihyde.com/?p=13

    I’m looking at getting ourselves ‘off grid’ to a certain extent – to the point where we could be independent of ‘services’ for a month or two.
    This solar/battery setup looks like a good way to get started at a resonable cost.

    Reading through your website, we are are of a like mind with what you and your family are doing at Lifeboat Farm, particially the article on ‘hedging’ – right on the money there.

    Cheers
    Peter (Matarawa)

  6. John Says :
    8 October, 2008 at 3:28 pm


    Thanks Peter. Your place looks lovely – well set up for orchards and gardens. This was our first toe in the water at off-grid living but we have quite a few more plans. Our new wood range has just arrived so we’ll be cooking with wood soon and with the amount of wind we get, a wind turbine is on the cards soon too.

    I’ll keep an eye on your blog for progress.

  7. Russ Says :
    20 February, 2009 at 11:27 am


    Hey John, you followed me on Tw(a|i)tter and so I checked out your site. As Peter says above, we have much in common (I guess you mus ave checked me out – so to speak – too.

    We’re going Semi-off grid in Kapiti (http://kapiti-off-grid.pbwiki.com) with a grid-tie system to come as we save up the el-dosho. Like Peter said too, def good to stat small. I might wire up our shed (when we build the darn thing, this year with luck) similarly to you.

    I’ll prob use drills and saws instead oh and a CB if I can get around to buying one..(I can’t help it, I’m a bit of a survivalist…not even a conscious decision)

    Oh that’s what I was going to ask – who is your range made by? We’re looking at Wamsler but are open to suggestions and 1st hand experience..

    Cheers,
    Russ

  8. John Says :
    20 February, 2009 at 11:55 am


    Hi Russ, thanks for stopping by.

    Our range is a Heritage by Homewood Stoves – http://www.homewoodstoves.co.nz/

    We have not regretted buying this stove one bit – it really has turned into the heart of the home. We’ve left our hot water turned off since Xmas and have hardy noticed. I’ll do another blog post soon on our newly halved power bills :-)

  9. Rose Says :
    13 August, 2010 at 10:09 pm


    Hey great site!!very fancy!
    ive been trying to work out what wcan do solar wise so this article was great. I am the she-who -controls-the-to-do-list at our place so solar is back on the plan!

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