alt.energy.renewable

> >... here in upstate NY, no passive solar method will amount to anything in
> >the winter due to the almost constant overcast.
>
> Inexpensive active solar works well in Rochester NY. Simulations with TMY2
> hourly weather data indicate that 240 ft^2 of twinwall polycarb sunspace
> glazing and an auto radiator and a 1000 gallon unpressurized heat storage
> tank can 100%-solar heat a house in a typical year and provide most of
> the hot water, with a minimum tank temperature of 91 F in December.
>
> If cloudy days are like coin flips, a house that can store enough heat
> for N cloudy days can be 100(1-2^-N)% solar-heated, eg 97% for 5 days.
>
> Nick

At 100% collection efficiency with no heat losses whatsoever in the
full desert summer sun, 240 ft^2 will collect 700,000 btus/day.
That's roughly 30,000 btus/hour, so we're sort of in the ballpark. In
reality, upstate NY gets half the average daily insolation (4 kwh/msq/
day) (480 ft^2), winter can reasonably be expected to be half of
summer (960 f2^2), and efficiency cannot be expected to exceed 50%
(2120 ft^2). That's quite a difference from the 64 square feet that
morris is claiming will heat a house.