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Advice on solar/photovoltaics/wind turbine (thank-you :0))

Posted: Wed Jun 20, 2007 8:23 pm
by Trinity
I'm very new to solar power. We are looking to go off the grid (at some point) and wish to have a small amount of electricity (for a laptop and a low energy lamp).

What sort of photovoltaic system would meet our needs. Ideally it would be portable and easily transportable.

Maybe we'd be better off with a small wind turbine? Perhaps it would be easier to maintain?

Any insight would be greatly appreciated!

Heartfelt thanks

Trinity

Posted: Wed Jun 20, 2007 8:47 pm
by Martin
The two are often used together - in summer you'll get around 6 times as much electricity from pv panels than you will in the depths of winter - which is when the turbine comes into it's own - there's usually more wind about in winter, and it should make up for the shortfall! :cooldude:
Siting the turbine is all important - you must have a clear run up to the turbine from the direction of the prevailing wind - no buildings, trees etc.....
The best way to decide what you'll need in the way of turbines and panels, is to start backwards! - decide what you will use in a day -
Example - one 18w energy saving lightbulb for 4 hours at 12v - 6amp/hrs, laptop through switched mode converter - 36 watts - for 3 hours - 9 amp/hrs-
so you could say that in a day, you'll use 15 amp/hrs - call it 20 to allow a margin - in a day, you should aim to take no more than 10% of the battery's capacity, so you'll need a minimum battery size of 200 amp/hrs. :geek:
THEN look at putting 20 amps a day back in - on a bright summer's day, you should get around 6 times the panel's rating per day - so the panel needs to be giving around 3.5 amps -multiply by 12 to give watts - 42 watts - ~SO, in this example, you could probably get by with a 60w panel for summer use, but you'll be sadly lacking in winter - you'd need around 300 watts of panels to do the job midwinter, and have loads to spare in summer..............that extra 240 watts of panels would cost around £900, so as long as the turbine site is good, it'd be cheaper to buy a small turbine for about £500 for a more "balanced" system. :geek:
Clear as mud! -hope it helps a bit!

Posted: Wed Jun 20, 2007 9:04 pm
by Trinity
Thank you for the prompt and clear response. I can just about get my head around the figures and really appreciate the info. 'Tis most helpful!

Also curious about the longevity of the pv and turbine? Are they easily transportable? and readily available in the UK?

Warm regards

Trinity

Posted: Wed Jun 20, 2007 11:01 pm
by Martin
longevity............pv panels must wind hands down! - some of the bigger companies are now guaranteeing 90% performance in 25 YEARS! Apart from cleaning them every once in a while, that's it - fit and forget! :cooldude:
Turbines longevity - very difficult to say - one chocolate teapot manufacturer said "10 years" with loads of ifs, ands and buts. You should check the turbines bearings and blades at least once a year, but there is no reason why a well-built one shouldn't be delivering electricity in 20 years time - it may have had a couple of sets of bearings, and three or four sets of blades, but it will probably still run! (aged Rutlands are to be seen on many boats, well into their second decade).
Yes, eminently transportable - I've just put together a package for someone who's off to live in Spain - turbine, tower and controller, pv panels and batteries - they'll be taking the lot in a small car! :cooldude:
And available..........well, inside a couple of weeks any package you choose can be put together and sent.......... :wink:

Posted: Thu Jun 21, 2007 5:30 am
by Trinity
Brilliant Martin!

That's given me a great start. I will check out your site too. Now I am armed with a few more facts I feel more confident. We are not quite ready to get these, although we are avidly preparing the details.

Warm Regards
Trinity

Posted: Fri Jun 22, 2007 2:30 am
by Wombat
One of the panels sitting on the roof of the garage has been sitting there for 25 years and seems to be charging away as well as the day it was put in!

Nev

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Posted: Sat Jun 30, 2007 8:26 pm
by onetoremember
We have a free ebook on our site - solar questions answered. It migh help........ :cheers:

Posted: Sun Jul 22, 2007 8:55 am
by Paul
Intreasting, Im all Electric, [No Mains Gas]
Heating & Hot water via wood burner stove, the rest is mains electric;
question, would solar/wind turbine give enouth power for cooking/PC/Stereo/washer ?

Paul

Posted: Sun Jul 22, 2007 9:13 am
by Martin
the short answer is "yes, if the turbine and size of panels is sufficient" - :cooldude:
BUT, it ain't that simple! Probably the best way is to look at your situation "in the round", and then decide the best balance of renewables.......
If you have no mains gas, and are dependant on electricity, you're paying top whack for your energy, so minimising it's use is very wise - I'd probably suggest solar hot water heating first - relatively swift payback, and means you can let the woodburner out from March - October, THEN look at replacing the electricity supply with renewables. At first glance, the "biggy" in your power consumption is probably cooking - it requires a heck of a lot power, which is expensive to generate and store, sometimes it can pay to look at avoiding the cost of electricity (bought-in or generated) by using other technologies (a wood fuelled "range" perhaps?), and then supplying enough for the lighter loads alone :cooldude:
If you're thinking of wind power, position of the turbine is all - IF you're in a good spot for wind it can pay back swiftly, if you're in the middle of an urban area, it could take a hundred years! PV panels are a lovely technology - fit and forget, and will probably be producing nearly as much power in 25 years time, but they are pricey to buy.
Many people use a combination of pv panels and wind turbine - to a great extent, the pv panels give a lot of power in summer, not a lot midwinter, the turbine will work best in winter......... :wink:

Posted: Mon Jul 23, 2007 4:30 pm
by Paul
Many thanks there Martin, Im going to look into this :cooldude: ,
I live in a small Rural Village, with a south facing back garden, & quite Windy, so its looking good.

Paul

Posted: Mon Jul 23, 2007 8:48 pm
by Paul
Think I must add, just had a look at your web site :cooldude: ,
Replacing my cooker with Alternatives makes a Lot of sense,
now working on Ideas & costs, will get back to you.

Paul