On 10 Dec, 23:15, Peter Parry wrote:
On Mon, 10 Dec 2007 21:52:49 +0000, David Hansen

wrote:
A 23% saving in gas. Most interesting.

Most interesting indeed. He has a single solar collector virtually
identical to the Thermomax one used in the DTI test (DTI/Pub URN
01/1292) tilted at a similar angle and with slightly less optimal
alignment yet managed to get 5,400kWh in a year wheras the Energy
Monitoring Company Ltd for the DTI could only manage 1,010 kWh from an
identical panel in one year.

It would be really useful to find out how he achieved the fivefold
increase in performance over a fully instrumented and monitored system
especially as it appears to be about twice the amount of energy even
falling on the panel in one year (from Navitrons figures which are
similar to the DTI ones).

Global warming must be much more advanced than we thought.

A Navitron 20 tube panel is about 2.5m2. The average insolation on
2.5m2 in the UK is about 0.25kW. Over the year that gives about
2.2MWh. The very best possible yeild from such a panel, attached to a
system designed to absolutely minimise losses will be half that. Thus
1.0MWh is a believable figure, giving a reduction of 40 pounds on your
annual gas bill, so long as you can store the energy with zero losses,
and don't have to dump any heat.

It is beyond the laws of physics to claim 5MWh from a 2.5m2 panel in
the UK. At 40 quid a year, it will only take 30 years for the 1.2k
system to pay for itself, by which time it will be scrap.

T