INSTALLATION – SOLAR COLLECTORS
11
INCLINATION OF SOLAR COLLECTORS
To help maximise system performance, solar collectors should be installed with
an optimum inclination. This is equal to 90% to 100% of the local latitude angle
when collectors are oriented within 60° of true north or true south, and between
10° and 20° when the collectors are oriented between 60° and 90° from the
optimum orientation.
Generally, improved summer performance is obtained from an angle of
inclination less than the optimum angle and improved winter performance is
obtained by an angle of inclination greater than the optimum angle. If the angle
of inclination varies by 20° from the optimum angle, the solar collectors will
receive about 10% less total annual solar radiation. The
are listed on page 12.
However, the optimum inclination of solar collectors is not always practical or
achievable. Solar collectors may be installed at the roof angle for simplicity of
installation and appearance, but must never be flat for a pumped solar open
circuit water heater installation. Although the solar collectors can be installed with
an inclination of less than 10°, this is not advised. The risks include:
the collector glass not 'self-cleaning', leading to dirty collector glass reducing
solar performance, and
condensation on the underside of the glass taking longer to clear, and
condensation droplets falling onto the absorber plate potentially causing
discolouration.
The collector kit is suitable for installations with an inclination of up to 45°. Where
the solar collectors are installed at inclinations greater than 45°, a With Pitch
frame is necessary. Refer to your local Solar Distributor for details.
A Variable Pitch frame can be installed to increase the angle of inclination of the
collectors used in a pumped solar water heater installation. This type of frame
should be used if the roof pitch either varies by more than 20° from the optimum
angle or is less than 10°.
The use of a Variable Pitch frame should be discussed with the system owner. If
this option is neither possible nor acceptable to the system owner, it may be
possible for an additional solar collector to be installed to help make up for the
reduction in solar performance compared to the optimum inclination. This option
should be discussed with the system owner.
If these options are neither possible nor acceptable to the system owner, then
the system owner needs to be made aware of, understand and accept that
increased boosting may be required to meet their hot water requirements.
