Environmental
breakthrough in solar water heating. Inventor "thrilled" at DTI report
on his new design.
A newly published government-funded study
of eight solar water heating systems confirms what has long been suspected by
Heavens Solar Technology: that the environmental benefits of a solar water
heating system can be substantially improved simply by eliminating the use of
mains electricity to run it.
In a nutshell, around 20% of the supposed
environmental benefits of using solar water heating are negated by using mains
electricity to run the system. This energy is referred to in the report as
"parasitic energy consumption"
As an alternative to these losses, it also reported that replacing the
mains power supply to the panel with locally generated solar electricity is now
a commercially viable option.
This 100% solar approach is used by our
Solartwin system. The solar electric pumped solar water hearing system, which
was included in the study only at the last minute because of its relative
newness, uses no parasitic mains power at all. Also important to customers
interested in saving money as well as the environment, Solartwin incurs no
electricity bills either, thus improving payback.
Background
Nearly all solar water heating systems use mains electricity not only
for measuring water temperatures but also for pumping the water through the
solar panels whenever the sun heats it. Of the eight solar water heating systems
tested, only, Solartwin, which generates its own solar electricity for these
purposes, did not suffer from this drawback.
The environmental impact of the systems was assessed in terms of how
each one reduced carbon dioxide emissions from burning gas in a boiler, carbon
dioxide being the main cause of global warming. What was remarkable about the
report was just how much of the potential environmental savings of each system
(apart from Solartwin) had be scaled
back after their use of mains electricity was taken into account.
Results
from the report
(Side by side testing of eight solar water heating
systems. October 2001 Funded by the DTI sustainable energy Program, Contracted
by The energy Monitoring Company, Written by Chris Martin and M Watson. Document
numbers: ETSU S/P3/00275/REP/2 and DTI/Pub URN 01/1292 2 Page 35 of the report,
first paragraph.)
Typically, this "parasitic" use of electricity meant that
global warming savings (CO2 reductions) had to be scaled back by 17% for “flat
plate” type solar collectors tested and 23% for “evacuated tube”
technology.
Cutting parasitic electricity use to zero is important to users of
solar water heating systems. Not least because people use solar precisely
because of its environmental benefits. A realistic way to get to grips with a
20% “parasitic electric effect” is to imagine you have used a conventional
solar water heating system for five years. During that time, one year's worth of
your system's potential environmental benefit will be negated, due to the mains
electricity needed to run it. Electricity consumption is damaging to the
environment because mainly "high carbon" fossil fuels are used in its
production, and furthermore, they are used rather inefficiently, as well.
Kerr MacGregor, inventor of the patented Solartwin solar water heating system
at Napier University in Edinburgh commented: "Not only does mains
electricity cost the environment dear in terms of contributing to global
warming, it can also cost the solar customer consumer money, year after year via
their electricity bills. Not so with Solartwin, which generates its own free
electricity to power its pump and control system. I am thrilled that the
benefits of solar pumping have finally been independently verified and that my
100% solar powered water heating system is now manufactured in UK and installed
here, and in Ireland.
Summery
calculations of results
