On Mon, 10 Dec 2007 15:26:15 -0800 (PST), Pete C
wrote:

You need to read on a little, quote:

"Actual cost saving works out to around £120 year-on-year. But, also
consider that as part of the package I spent a further £300 to improve
the exisiting CH/DHW controls to meet full Part-L specification so not
alll the saving can be attributable to the solar installation. However
this included dual cylinder stats on separately timed zones to
maximise the solar gain vs boiler operation."

Of the 5,400kWh saving no more than about 20% of that can be
attributed to the solar collector, there simply isn't enough energy
falling on the panel to produce significantly more. This is nothing
to do with how good or otherwise the solar panel may be - the energy
isn't there to collect.

If 80% of the saving came from the relatively modest (in cost)
alterations to the controls this obviously represents a far better way
of spending your money but is a lot more than most authorities would
estimate you would save. Its simply impossible for the panel to
produce more energy than it can possibly collect so I'm interested in
what did produce the observed effect.