alt.energy.renewable

bill wrote:
>
> > >... 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.

Umm - two 6'x8' panels works out to 96 ft^2 on my calculator, and
I've only spoken about a farm shop building (not a house) because
that's the only installation for which I can provide both photos
and owner feedback.

With vertical panel orientation, winter output is considerably
more than double summer output - and when the ground in front of
the panels is snow-covered, output can increase by more than 90%
due to capture of snow-reflected energy.

I can't buy your 50% efficiency, but won't argue that until I've
actually got measurements to back me up - but I'll warn that I
think your number is much less than what I expect to measure.

I'm glad to just take your word for lousy weather where you are.
:-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/