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Post by brookstrb on Feb 14, 2013 14:27:45 GMT
Hi,
I'm moving to an old smallholding with a barn (no electricity) and an old house (mains hookup). I will be living in the barn and converting some rooms in there before the house. I want to move to be completely off grid but due to financial limits need to do it in stages.
I want to first wire the barn to be a glorified caravan. I have a 80w solar panel, 125ah batter, 10A regulator, and 300w inverter, which I used last year to live in a caravan. My electrical needs are small and this will do me for most of the year. My wife however would like a mains backup until our reusable supply is a bit bigger.
My question is how can I build a system starting with the solar I have, 12v lights, 240v inverter etc, but with some kind of mains backup, and which will enable me to build more panels into it as I go. I've seen something about Grid tie inverters, but I'm not sure how they work, and it needs to be something I can wire in myself.
My hot water and cooking will come from solid fuel as we have plenty of trees, so its just lights, charging laptop batteries, hand tool batteries etc.
I'll leave it there. If this is the sort of thing people can help with I can give more details.
Any help appreciated.
Regards,
Terry
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Post by Firefox on Feb 14, 2013 14:46:52 GMT
I'd go for another couple of 100W panels and another couple of batteries at least. Probably about £300 worth.
But initially on a budget, why not go for a cheap genny? A 1 or 2 kw one will only set you back £200 which will give you the back up you need to power your kit and charge your battery back at the same time.
If you have diesel vehicle you could even use that to begin with, running the engine on idle to charge your battery off the alternator. OK, it's not the best, but diesels are relatively efficient on idle and you wouldn't have the initial capital outlay.
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Post by Etienne Le Croq on Feb 14, 2013 15:05:54 GMT
Panels are cheaper now, so as Mr Fox says buy another panel and battery,that will add to what you have now and a gennie will get you out of trouble.You could wire a caravan 240 volt consumer unit in with an input socket outside and plug a gennie in,then you could use a mains charger on cloudy days.
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Post by n brown on Feb 14, 2013 15:58:55 GMT
hopefully someone else will know more,but back in the mists of time i messed around with this sort of thing and got hold of a lot of large glass wetcell batteries,each one was 1 1/2 volts,so had them in banks of 8. the terminals were nuts the same size as on my bedford,about 1 3/8 ".massive.the point is that i seem to remember they came from british telecom,and like traffic light bulbs were changed regularly whether necessary or not,then disposed of. now i don't know if these type of batteries are still around but i bet batteries from solar powered signs are changed long before they die,and are available cheap or free. i got the idea from Mother Earth magazine,check it out
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Post by Firefox on Feb 14, 2013 16:14:42 GMT
Diesel car/van on idle - could be free if you have one? Running costs £2.00- £2.50 an hour? 12V cabling. Could be a couple of sets of old jump leads if battery is near the car. Park close to wall/window and feed leads through. Jump clips off car battery. As short and as thick as possible. £25
Genny - could be second hand £150 ? Running costs £1.00 an hour Caravan hook up inlet £30 Consumer unit £50 Smart charger £40 Cabling £30 £300 set up - Very ball park figures. Probably could do for < £200 if you get some bargains/second hand
2x 110Ah Batteries - £150 2x 100W solar panels - £150 Running costs free. May still need Gen or car back up for bad weather. 30A regulator - £40 Cabling/connectors - £40 £380 set up - probably the best long term option. Could add even more panels if a barn.
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Post by brookstrb on Feb 14, 2013 19:05:24 GMT
Thanks for all your help!
I think the generator is a good idea. In the short-term I need some extra power to run an electric shower, this seems to be our easiest way to get hot water until we sort out a solid fuel system. I can either use a generator for this or run just one main cable from the old house to the shower, maybe with a plug attached to charge the batteries of the lighting system, which could easily be 12v.
I suppose it might just be easier to run the whole thing off the house electric in the short-term, and wait for off-grid projects till later. I am worried though that when we get the electric we'll suddenly end up with a fridge and washing machine and then there will be no getting rid of the mains.
I wonder if anyone has an example a wiring diagram, or knows of a place that has them, for running a grid tie inverter alongside a solar, wind, and other sources, system? If I can do this it sounds like I can just plug the mains in and get it too all work automatically, might be a bit naive!
I'll keep working on it, if I can make it look worthwhile I might be able to persuade everyone else its worth it.
Cheers,
Terry
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Post by Firefox on Feb 14, 2013 19:56:44 GMT
I'd check rating of your shower. Some of them are 2KW or 3KW and a genny may struggle unless it's a big one. May be better to run a cable if the house 240v is still on.
Easiest way to get hot water may be propane cylinders and small 2 gas burner camping stove. If you use 6kg cylinders and buy an adapter off ebay you can fill them at LPG stations for £8 or £9 rather than £23 for an exchange cylinder. (not strictly "allowed" but I do it)
You can run a small fridge full time off-grid using about 300W of solar panels and 3 batteries to store charge.
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Post by brookstrb on Feb 14, 2013 20:04:38 GMT
Cool! Nice to know.
Thanks for your help!!
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Post by Firefox on Feb 14, 2013 20:18:04 GMT
No problems I should mention that you'd want a 240V/12V compressor camping type fridge one of the new efficient ones about 40-50W. Alternative is absorption fridge running off solar panels some of the time when you get enough sun, and cheap propane otherwise, or even from Genny if that is on. Expensive to buy new though 90 litre 3-Way fridge is about £600!! Caravan breakers better bet maybe.
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Post by tommy on Feb 16, 2013 17:05:24 GMT
Keep an eye out for 20 x 55w amorphus panels on ebay for £395 which is an absolute steal of a price for 1.1kw and still generate in poor conditions... you could knock up a nice "awning" with a couple of poles and cross beams and use them for the roof !
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