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ENVIRONMENT AND ENERGY
Solar Thermal systems can be operated without electricity, relying on solar energy to provide a reliable supply of
hot water.
suggest that solar thermal systems could meet 70-80%
of low-temperature heating and cooling demands.
Comparing solar thermal and solar photovoltaic
systems
“Most South African plumbing contractors are familiar
with the installation of small solar thermal (ST) systems,
typically found in residential housing. These ST systems
can be operated without electricity, relying on solar
energy to provide a reliable supply of hot water. However,
these systems have evolved to include electrical
pumping systems and storage that makes them suitable
for larger installations.
“Solar photovoltaic systems (PV) produce electricity that
can be used to meet electrical requirements through an
August 2019 Volume 25 I Number 6
array of solar panels and even be coupled to batteries
as a storage means that makes this electricity available
when there is no solar resource. In other countries,
one can sell excess electricity back to the utility but in
South Africa this is not yet an option. It is possible to
use PV systems with storage to go ‘off the grid’ entirely
but owners need to consider energy security and
the availability of immediate maintenance and repair
should system problems arise. In addition, the owner
will still be paying to remain connected to the national
grid, so why lose that back-up?
“In terms of efficiency, however, experts agree that ST
systems can deliver approximately three to
five times more energy than PV systems of the
same dimension.”
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