Wednesday, March 25, 2009

What's the best solar energy solution for a garden office?

A reader of Shedworking has written in with the following query. I've suggested a couple of possibilities but please do comment with your own thoughts:
"I read your Ingalls Street Studio post with interest as we’re getting closer to starting my outbuilding project. Basically, we have a brick outbuilding that is about 10ft x 12ft and is ripe for conversion to a home office.

One of several things that needs doing is sorting out a reliable electricity supply with fuse box etc, so that all my gear isn’t running off an extension cable, or some other hazardous setup. I will be getting a sparky in to do an armoured cable in a trench, but I spotted the mention of solar power that could supply the bulk of power requirements, with the remainder coming from the mains.

What sort of panels are required for this? Do you know anyone in the solar business that could impartially advise me on this?"
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6 comments:

  1. Hi Alex,
    I had a look into this a while ago and the results are at http://www.secrets-of-shed-building.com/solar-shed-light.html . In summary, there is quite a long period to repay the initial outlay if you are looking to power office equipment etc. So mains power could be the best if demands are above those of simple lighting.

    On a different tack using solar power for heating can be installed in a diy fashion quite cheaply as passive solar. This uses the suns rays to heat the air directly. This can be a good way to reduce heating costs fo a garden office, I have an article coming up on this in the near-ish future.

    All the best

    John

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    1. John,

      I would be really interested in reading your article regarding the solar for heating, please can you let me know where I can find this.

      Many thanks

      Paul

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  2. I've seen lots of solar powered lighting and ventilation solutions but the size of the cells used is hopelessly under powered and the amount of light from a single LED is barely enough to find your office let alone work in it.

    I found this chap making 15W panels on the cheap the other day, it gives you an idea of the wattage for a given surface area.

    http://www.workshopshed.com/2009/03/making-low-cost-solar-panel.html

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  3. Hi Alex,

    I recognise that email! Thanks for throwing it open to your readership, much appreciated.

    Thanks too to John and Andy - I'll read those pages now.

    I like the idea of using solar for heating; that might be a more sensible first option, given the other costs of getting the outbuilding insulated, re-reoofed, decorated, hooked up to mains, etc, etc...

    Cheers

    Austen.

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  4. Anonymous10:02 PM

    Here's a process that you may follow...

    (1) The key thing is how much roof space can you spare, and how much sun does that roof get? Let's assume you're in Southern California and you get on average 5.5 hours of sun per day. Let's assume you have enough room on your roof for four 200 watt panels (each panel is roughly 3' x 5' and costs $800).

    (2) Next buy inverters. These convert the electricity from the panel into electricity you can use and tie the panels into the main power grid. I'm going to suggest a new product called micro-inverters. They cost $200 each, you need one for each panel.

    (3) Mount the panels on some racks and tie the microinverters to the grid. This will likely cost $1000 and entail hiring an electrician to run some conduit. Those 4 panels produce, over the course of a year, 1284 kwh, in S. Cal. Your computer, a lamp, a printer, and a few other small appliances (no heater, no stove, nothing that just burns electrons outright) likely consumes about 1/2 a kwh per hour of use. Over an 8 hour work day, 250 days per year, you will consume 1000 kwh. If you use a laptop, i bet you could drop that by 2/3.

    Either way, in S. Cal, that system would oversupply your shed so much so that with a laptop, you could do it with half as many panels. The cost for a system with only 2 panels would be not much more than an expensive computer cost a decade ago... and it'd be fun to know you were sorta independant!

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  5. By using different kinds of alternative energy sources you’ll also be able to save money being that the required equipment is becoming more available (the one that makes things work!), revolutionizing the way we use energy!

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