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re: solar power efficiency pv vs heat collector
25 jun 1997
ruppert georg wrote:
>nick pine wrote:
>>...if we really need seasonal storage, how much would it cost to build a
>>5 meter cube full of water drums, sitting outside on the ground, with a
>>flat rubber roof, surrounded by strawbales?
>good idea, but not very feasible in austria where local authorities will not
>allow such "buildings" in general.
i wonder why. our building codes usually only talk about safety and health,
vs aesthetics, and the front of the code has a statement like "no matter what
the code says, if you can convince the building inspector to let you do it,
it's allowed." in this case, there might be a nice ecological reason. perhaps
it would help if the walls were made of used tires filled with compost :-)
>>or maybe a small insulated box full of water to store heat for a cloudy week.
>
>what is small for you? take a typical low-energy house from my country:
>assume 5kw necessary heating power * 10h operation during the day giving
>an energy consumption of 50 kwh per day which is roughly equal to the
>energy you get from a 1000l (250 gallon) when you cool it down from 90°c to
>45°c. so for a week we need a 7000l (1750 gallon) tank without even
>considering isolation loss. a rather substantial "small isolated box".
i guess i shoulda said "smaller," eg 32 vs 256 55 gallon drums. or maybe
just a couple of uninsulated drums, if the heat is stored by concentrating
a lithium chloride solution in a solar still, and recovered by condensing
water out of ground-heated house air at 1000 btu per pound of water.
nick
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