On Sun, 14 Oct 2007 06:12:46 -0700, Jonathan
wrote:
The big problem with the CAT is that it is ALTERNATIVE not MODERN
technology. The last time I looked, they were using inefficient flat
panels from the 70's.
Actually the "modern" vacuum tubes being sold at inflated prices
pre-date the 70's by a considerable margin and were in domestic use
in the mid-70's at least. They are not exactly "high tech", their
advantage from an salesman's point of view is they look it and can be
used to fool the gullible. The problem is that in the UK they are
not all that much more effective than the flat panel.
For some unbiased data the DTI report ETSU S/P3?00275/REP/2 DTI/Pub
URN 01/1292 gives the figures for vacuum tube and flat panel systems
which were monitored over 7 months. They found little difference
between the overall system performance of flat panel and evacuated
tube systems.
In general the systems produced 75% or more of the domestic hot water
requirement during May Jun and Jul, between 50 and 75% in Aug and
Sept, Less than 30% in Oct, and about 10% from Nov to Jan rising to
20% in Feb and 40% in Mar. For most people that doesn't produce a
saving of £75 per year much less "many times more".
Indeed your favoured Energy Saving Trust in their report "Potential
for Microgeneration Study and Analysis Final Report 14th November
2005" say
"[Solar water heating is] Currently the largest microgeneration
industry, installing 2000 units annually. Generally, solar water
heating is not cost effective at present. The technology is most
effective if replacing electric heating systems."
"Solar water heating (active solar): reductions in generated energy
cost are required for break even with electrical water heating.
Break-even is not predicted for gas (or oil) boiler water heating.
This is because of high capital costs combined with low oil and gas
prices. Approximately 50% capital cost reduction is necessary for
break-even with electrical water heating by 2015 –2020."
"Solar water heating does not break-even with gas boiler water
heating, and will require large cost reductions to break-even with
electrical water heating by 2015 –2020."
--
Peter Parry.
http://www.wpp.ltd.uk/