R&D is still ongoing and the prices will drop accordingly when packaged
solutions are available.

There's a limit to how much cheaper it can get, it'll always be a
complex motorised thing.

There's a lot that can be done with
simple materials. You might
achieve a collector efficiency of only
60% compared to maybe 80% of a
vacuum tube collector

In this case use more collectors.

Indeed. This is my preferred this idea.



Sun trackers get 3 times the suns energy than flat plate collectors. So
much so they are powering Stirling engines.

This doesn't add up. The amount of energy available per square meter
is the same for any collector. At the height of summer, this is about
800-1000W per square meter. A suntracker maintains alignment with sun
so it's exposed area does not diminish as the sun moves. It might also
be 10-20% more efficient than the cruder panels but this doesn't add
up to 3 x difference...


Active solar in the UK is viable. The solar closet can be an air heater
inside a conservatory facing south.

An air heater?

A solar closet has a high thermal mass and high insulation. It's
basically a cube shaped room. A 1 meter cube would have 10cm of (say)
rockwool insulation, the rest of the space would be occupied by water
filled containers which can hold a lot of heat energy. A conservatory
is filled with air and even good double glazing is not a great
insulator.

Nick