1. www.plumbingafrica.co.zaVolume 16 I Number 6
Our government sees Solar Water Heaters (SWH) as
the ideal way of providing hot water to communities
with no burden of monthly bills, and for Eskom, SWH
are a means to reduce the ever increasing power
generation requirement.
For many however, their recent bad experiences with
SWH have led them to ask the question: "Are SWH really
the solution?” There is no doubt that SWH are the solu-
tion and that they are here to stay. Indeed it is surprising
that it took South Africa so long to realise their potential.
The systems have been widely used throughout the rest
of the world even though, for example, most of Europe
cannot harvest more than 1600 kWH/m2 per year. Most
of South Africa, by comparison, can harvest in excess of
2000 – 2400 kWH/m2.
It makes so much sense that SWH should be widely used
in South Africa, but it is important to make sure that
these systems add value and do not end up costing
more in the long run. This is where the SABS plays a
critical role. There are a large number of standards that a
SWH must comply with and the SABS is well equipped to
deal with them. The 'parent' specification is SANS 1307
“Domestic Solar Water Heating Systems”. This standard
contains a list of requirements including up to 23 addi-
tional standards that might have to be verified, depending
on the design and construction of the system.
All requirements are equally important – no single
requirement is more important than another – but the
requirements listed below are regarded as some of the
main areas for testing.
Mechanical Tests – SANS 6210
These include a variety of mechanical tests to ensure that
the system is of sound construction and will be able to
withstand the physical demands of water pressure and
extreme weather conditions. The stagnation test involves
exposing the system to the sun for about 15 days, with
no water in the system. During this test some metal
Solar Water Heaters –
enduring South African conditions
Solar water heaters are a hotly debated topic at present. As homeowners,
we are in search of ways to use less electricity and keep costs down.
By: Herman Stauss and Karel Deist
components might reach temperatures of over 200°C.
Inferior design or materials result in distortion, damage or
malfunction during this test.
During the hydrostatic pressure cycle test, the sys-
tem is subjected to 250 000 cycles between 0 kPa and
the maximum working pressure of the system. A system
experiences these cycles in real life because the heating
of the water causes thermal expansion of the water. After
the cycle test it is subjected to twice the working pres-
sure. A typical failure that is revealed during this test is
weakness around welded areas.
To test resistance to rain penetration, water is
sprayed in a controlled manner over the system. If for
instance any seals or the glass cover were compromised
during the stagnation test, this test would allow water to
enter the panel and reduce its efficiency.
A system that is at the mercy of nature must be
able to withstand the sizable hail storms experienced in
various parts of the country. During the hail resistance
test, 12 ice balls are shot at the system with the energy
being 11 J ±1 J.
The aim is to target the weakest spot. In the cold ar-
eas of our country the temperatures drop below freezing
point in winter. When water freezes it expands and some-
thing has to 'give', for example, the pipes or the panels
themselves. The resistance to freezing test involves
subjecting the system to a temperature of -20°C for a
period of four days to test that the SWH freeze protection
system functions effectively. The test for resistance to
dezincification is commonly performed on all plumbing
components to ensure that the corrosion resistance
properties of the brass components are up to standard.
1. Karel Deist is Head of
Laboratory and technical
specialist, plumbing, pipes,
mechenical, water meters
and solar laboratory.
2. Herman Strauss is
Manager: mechanical,
fluid and pipes.
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68 Did you know...from the SABS lab
Plumbing Africa

2. www.plumbingafrica.co.za Volume 16 I Number 6
Did you know...from the SABS lab
Plumbing Africa
69
Thermal performance
test - SANS 6211
The basis for this test is that the system is filled with
water of a known temperature. It is left in the sun for a
day while the solar irradiance is recorded and at the end
of the day the water temperature reached is recorded.
This information is then used to calculate how much of
the available solar energy was transferred to the water.
The process is carried out over a six day period, while
various conditions are simulated.
The end result is a formula that can be used to predict
the performance of the system for any expected weather
condition. For the Eskom rebate program, a “Q factor” is
calculated. This is the amount of energy that the system
would absorb on a day with a solar irradiance of 16 MJ/
m2
and a difference between the ambient temperature
and the water temperature of 10°C. This test provides
information on the efficiency of the system in heating
the water and is an indication of the energy saving that
will result.
Ongoing test improvements
The measurement standards used by the SABS are
developed by a technical committee comprising experts
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The outer casing of this system
was cut open to identify the
area where a leak occurred
Karel Deist of the SABS with
the hail test machine
A freeze test in progress
Systems on thermal
performance test.
from industry and academic institutions. These
standards are seen as dynamic and are regularly
reviewed and updated as new field information
becomes available.
The SABS test laboratory is responsible for
performing the tests accurately and without ques-
tion to ensure that good quality, safe products are
distributed to the benefit of the consumer, and to
promote use of sustainable energy.
Ongoing test improvements
The measurement standards used by the SABS
are developed by a technical committee compris-
ing experts from industry and academic institu-
tions. These standards are seen as dynamic and
are regularly reviewed and updated as new field
information becomes available.
The SABS test laboratory is responsible for per-
forming the tests accurately and without question
to ensure that good quality, safe products are
distributed to the benefit of the consumer, and to
promote use of sustainable energy. PA
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