Bear in mind that it takes practically as much energy to heat your water from 15 degrees Centigrade to 20 degrees Centigrade as it does to heat it from 40 to 45 - so even if you let the solar do the basic legwork and then give it an hour-long blitz with the electric heater when you get home, you are saving relative to using electricity the whole time. This means you effectively do get some heating on a chilly-but-sunny winter's day, as long as the whole family times their showers nicely so the water temperature in the bottom of the tank is more than 5 degrees below the temperature in the collecting tubes (there's an electric display in the airing cupboard) for the longest amount of time. Of course electricity vs gas is another question, electricity seems quite an inefficient way to heat water to me!
I point out that a grant from the Low Carbon Buildings Programme would reduce the payback period considerably, and I'd happily bet on gas price hikes over the next 20 years. In short, I'd probably apply for a grant for my own solar passive water heating if I owned a house with a suitable roof (unlike photovoltaics, I don't think the price of solar water heating systems is going to fall dramatically in the next 2-3 years), but of course I'm renting too. And renting, with all the sharing of space and heat and such, is possibly more environmental and economic than owning.
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timeasmymeasure
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Date: 2008-07-01 06:00 pm (UTC)I point out that a grant from the Low Carbon Buildings Programme would reduce the payback period considerably, and I'd happily bet on gas price hikes over the next 20 years. In short, I'd probably apply for a grant for my own solar passive water heating if I owned a house with a suitable roof (unlike photovoltaics, I don't think the price of solar water heating systems is going to fall dramatically in the next 2-3 years), but of course I'm renting too. And renting, with all the sharing of space and heat and such, is possibly more environmental and economic than owning.