Anybody here off grid?

[caithnesscrofter]

Would be interested to hear about off griders set ups. We will officially be off grid in March and are looking at different options for our power needs. I read so much conflicting information about alternative energy it makes my brain crazy. Would appreciate any experienced users advice.

So far, we've got two lights that are solely powered by solar. (two is all we need)

We need to power...

laptop
printer (10 mins only a week)
speaker system for computer
modem
blender (5 mins a week)
occasional charging of power tools and digital camera
I also suspect we will want a small fridge too.

anybody got a recommendation for example what size wind turbine I might expect to need? or anyone have similiar energy needs that has a reliable system?

we are also thinking of getting a double battery system in the truck that we can hook up an inverter to to charge stuff like the camera and power tools. ideas for the cheapest set ups welcome! :-) we are also looking to have various types of systems instead of depending on just one type.

[Martin]

how long do you need to power the laptop for per week? - they soak up a lot of power, and if you're looking at running it for several hours a day,you'll need quite a lot more power than if it's only intermittent use.
The problem with the wind is that it doesn't blow to order - we've just had several days of flat calm, and we now have wind gusting to 54mph!
With very modest needs you could probably get by with something like one of the "cheapie chinese" turbines for around £300, but don't stint on batteries - at the very least, you'd need 4x110amp hr deep cycle batteries (car batteries just don't last)
I've been faffing about using various different chargers when caravanning, to keep things like lanterns, cameras and computers charged - generally, if you can get a 12v charger, it uses a heck of a lot less current than using the mains charger powered from the same battery by an inverter. Mobile phone mains chargers are particularly "energy guzzling", the 12v "car" version taking about a tenth of the current!
On the subject of inverters, you can get cheapie "modified sinewave" ones for around £25 - they will power many things quite satisfactorily, BUT it's very difficult to know in advance if a particular piece of equipment will work well - I've got a TV that hates it - you get a furious buzzing from the transformer, which doesn't augur well. I'd suggest lashing out on a true sinewave inverter (from about £85) - the extra is well worth it, you're far less likely to "fry" anything electrically delicate.

With turbines, position is all - in simple terms, if you live in a town, you are extremely unlikely to get a good output - surrounded by open countryside, with no obstructions, it should go like a dingbat!

You could certainly "do it cheaper" by buying secondhand, building yourself etc, but I'd give the following very rough budget -
Cheapie turbine, mast and modified sinewave inverter kit - £300
Batteries £200 (MINIMUM)
Charge controller £100
Cabling etc. £50
-to which I'd be very tempted to add -
150w True sinewave inverter £85
AND, if the budget allows - add around 120w of photovoltaic panels and a controller - another £450
Hope that helps a bit!

[Martin]

forgot the fridge - my suggestion is to go for a "three way" camping fridge - run it off bottled propane, or 12v in emergency (fridges use a LOT of electricity)

[caithnesscrofter]

forgot the fridge - my suggestion is to go for a "three way" camping fridge - run it off bottled propane, or 12v in emergency (fridges use a LOT of electricity)

we are gonna start off without one and see how we get on. maybe we will just learn to live without one in the summer... don't need one in winter so...

[caithnesscrofter]

so, if I charge up my laptop battery with a 12v instead it will sook alot less power? that sounds great if that is the case.

I use the laptop alot because it is the internet, phone, stereo and very fuzzy BBC, video player and part time job all in one! :-) I suppose an estimate of 8 hours is good.

what size turbine are you talking about? and yes, the turbine will be in open countryside.


thanks for your reply Martin.

[Martin]

there are a few laptops that have a "12v" power pack, but most demand something around 20 volts, so it's usually easier to use an inverter with the mains charger! If you run one for 8 hours, it'll probably be drawing 6 amps, so that'll be 48 amp hours a day - add in your other bits and pieces, you need to be able to draw probably 70 amp/hrs/day - classically you'd need ten times that capacity MINIMUM of batteries - 7x110 amp/hrs (you should design it to only use around 10% of it's total capacity per day)
In short, there are two schools of thought on batteries -the first is to buy some deep-cycle flooded lead-acid batteries as cheaply as possible (usually around £50 for 110amp/hrs), and don't discharge too deeply, and accept the fact that they will need replacing quicker than some - they are relatively tolerant of overcharge, not in the least tolerant of deep discharge (you need to ensure NEVER to take them really low, or you can end up with a duff battery bank) - they will also need topping up from time to time (gloves and goggles job). For most uses, I prefer advanced glass mat gel batteries - they require no topping up, have a much longer predicted life, and can be occasionally deeply discharged without killing them stone dead (useful when becalmed) - you have to make sure your charging circuitry is spot on - they hate over charging! They cost around 50% more, but are well worth it!
£300 will buy you a 200w Chinese turbine - if funds allowed, I'd probably go up to a 500 watter for around £525 - then when the wind is blowing, you can grab so much more power quickly!
The problem is with the "peaks and troughs" - get becalmed for 10 days, you've used 700amp/hrs -flattening your batteries completely if you've gone for the "minimum" seven 110s! (which you mustn't do!) - SO you then either need a much bigger battery bank, or to supplement with pv panels - or both!
Which is when most people decide to "cheat".......keep a small generator for getting you over the troughs, it's a lot cheaper to run that occasionally, rather than cream crackering your battery bank!
(If you're a tinkerer, howsabout a Lister diesel running on waste vegetable oil?)

[camillitech]

hi caithness,

i've lived off grid for 20 years and would pretty much agree with what martin says though i don't think a chinese windmill would last very long in caithness. personaly i would go for a proven 600w on a good homemade mast. if you can't afford that then i would get an ampair hawk. only 50w but indestructible.

we have a proven 2.5kw which has stood up to 100mph winds no problem. though we did run a rutland 910 for 15 or so years, however i would not recomend one of these. we only managed to keep ours going because i had about half a dozen scrap ones to cannabalise. like martin says good batteries are important.

good luck paul

[Martin]

You may well be right - in an exposed spot, the Chinese ones wouldn't be at their best - they are better in lowish wind areas!
Provens are damn good, but they are blessed pricey - there are some new English turbines rumoured at a keen price sometime soon, designed for heavy work, but there is a shortage of good turbines of "domestic" size., and at an affordable price - these are certainly worth a look! - http://www.fortiswindenergy.co.uk/index.asp?id=10

[camillitech]

yes martin could not agree more. i love my proven but it is hellishly expensive for what it is and i think better production methods and competition may well lower the price. i took mine down after a year to service it and it still looked just like new inside and it has stood up to some ferrocious weather. our island suffers regular power cuts for days on end but we are never without power at our house

[red]

maybe with the fridge you should think of alternatives - like a gas powered one as Martin suggested, or I remember once coming across this old fashioned set up - it was a box surrounded by porous materials - like pumice stone - and had a bowl shapein the top - you poured water into the bowl bit - and it soaked into the pourous material, then cooled the box through evaporation.

Evaporation works very well - when we are camping - often soaking a towel and throwing it over drinks etc makes a huge difference. just a thought

[Chickpea]

Lehman's have all kinds of weird and wonderful non-electric devices such as fridges, washing machines, driers, all kinds of things. The trouble is the cost of shipping them from the States is enormous. Is there a British supplier of similar things?

[caithnesscrofter]

I think we will have to learn to live w/o a fridge until we can build our cold store/cellar. Great idea about the evaporation method too. I will be experimenting with this!

Our neighbour has the Proven 2.5 but, it is run into the grid... I don't see much point in this myself. A Proven 2.5 with the battery system is £11,000 WITH a grant! sheesh. A bit out of our budget. :-) I will be looking into some of the others suggested here.

Aye... the Lehman's catalogue... what I would do for one of the concave cast iron dutch ovens!

[camillitech]

i quite like the look of the samray wren caithness but i dunno much about them. perhaps martin could enlighten us. it seems a rugged enough piece of kit to me.

[Martin]

The Wren is a nicely built little turbine that works very well - they've been tested out in Montana, and are well up to coping with a hefty wind!
-follow the link in my "sig" for further details!

[caithnesscrofter]

aye... let's hear about the Samrey Martin. :-) How many batteries would you need for the Wren?

back to the evaporation fridge.. I see Nev wrote an article on the zeer pots.. do both pots have to be unglazed?