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[PVpost] Small-scale (home) generation
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Joined: 05 Sep 2007
Posts: 14262
Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Mon Jun 08, 2009 3:36 pm    Post subject: Reply with quote

The hot weather of late has made our SolarTwin a worthwhile project. If there's no sun here in Ireland, you tend to put down a fire in the evening anyway, so the combination of wood fire heated water or solar heated water is fine for us, reducing our immersion heater use to an absolute minimum.

I'm currently working out exactly what power is acquired by the solar panel (based on 200 litres raised by 1 degree = 200,000 calories of heat: would that be right?) just for interest's sake.

Also, this is another quandary: although the tank of water itself rarely gets to 60 degrees, the water passing through the panel has been reaching 74 or 75; as this is the actual water eventually drawn at the tap (as opposed to antifreeze mixture), does this eliminate the chance of legionnaire's disease?
"Buddhists say we come back as animals and they refer to them as lesser beings. Well, animals aren’t lesser beings, they’re just like us. So I say fụck the Buddhists" - Bjork
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Joined: 02 Jul 2007
Posts: 6777
Location: North Somerset

PostPosted: Mon Jun 08, 2009 5:10 pm    Post subject: Re: solar water heating Reply with quote

billbrooks wrote:
We have looked inot the cost of running the solar water heating pump on mains and it is very low. Firstly the pump only runs intermitantly when ther is 6 degree temperature difference between the solar heating collector and the hot water cylinder and because ther ar no retrisctions in tthe circuit (which you usually find in a central heating circuit) the pump has to do a lot less work and can be left on the lowest power setting see

Welcome, the cost of running a solar heating pump on grid power is indeed very small, and has the advantage of simplicity and least first cost.

For various reasons though, many prefer a PV powered circulating pump.
Firstly there may be no grid supply available
Secondly, one may desire protection against power cuts
Thirdly, every little helps in reducing ones grid power useage, and a circulating pump is an ideal load for PV since it is required only in sunlight.

Finaly the more doomerish members here fear TEOTWAWKI and therefore want a completly self contained system not reliant on even a little grid power. Since spares might be problematic one should store a spare pump and PV module in that case.
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
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