Joe Fischer wrote:

"cynic" wrote:

I installed a system a few weeks ago. My vacuum tube array collector is
vertical on the gable end. I was faced with a cylinder replacement and
decided to go solar rather than stay limited to fossil.
The whole batch of kit and pipes came to £1100.

How many square feet did that 1100 pounds buy?

The array is approximately five feet by five feet but this is
interspaced by the gaps between the tubes so meaningless really. The
tubes are about five feet long and 2.5 inches diameter

I was dubious about
the effectiveness of having the panel vertical so I have used 4 "L"
brackets to mount it to the wall. If I find it lacks performance when
the spring comes round I can simply extend the bottom brackets with
mild steel bar.
with the present dull weather we do notice an elevation of the
temperature of the cylinder bottom by about 15 to 20 degree C on many
days (the sensor is about 300mm above the base of the cylinder) It will
be interesting to see what happens to our energy bill over the next
twelve months.
Obviously I would like a decent saving but its an experiment with a
potential for economy
John

It sounds like excellent planning, you might even
want to make the angle adjustable for each season.

I'm not so much concerned about the angle of incidence of the solar
radiation since the net effect of having the tube angled or square on
to the sun is minimal, its still illuminated. What I was concerned
about was degradation of the convection currents within the reduced
pressure fluid inside the fairly narrow copper collector core tubes.
As I said I am treating this as an experiment and may alter things
around to see how it responds

Vacuum tube arrays could possibly be produced
fairly cheap, just as 4 foot fluorescent tubes only cost
99 cents the last time I bought them, but I don't have
much hope of seeing them sold to the DIY gang in
small quantities at a good price.

e-bay is your friend!