Solar ACs can be a great low emissions alternative to traditional
cooling. Essentially, they refer to any AC system that is powered by directly by solar
outlay: High upfront cost for the time being given the immaturity of the
technology, but cost is expected to come down & energy efficiency to
increase in coming years as the tech improves. Currently, the system costs around
$4,000 to install, including having solar panels fitted –four to power a small
unit, and up to eight for a larger unit.
Solar ACs can bring your cooling bills down to about 10c a day, and don’t
require an existing PV system (similar to solar hot water). There's no need for inverters or charge controllers as they work directly and will
power on during the day when there’s sunlight, and power off when the light
fades, and it becomes naturally cooler.
Because they work independently of the grid, you can leave them on all day
without worrying about the cost. Savings over the lifetime of the units could
be between $8000 and $30,000 (reportedly)
The tech explained:
There are 2 types of solar ACs
Solar Powered Cooling System
Conventional solar air
conditioners utilise a standard vapour compression refrigeration cycle to cool
or heat the building in question. The principle is that heat in the
building is transferred to a refrigerant gas, which is then circulated out to a
condenser where the excess heat is dumped. The now cool refrigerant then
circulates back into the building to repeat the cycle. A conventional solar AC
system draws operational power from a solar array rather than the electricity
grid, in an effort to increase efficiency and lower costs.
- Open-loop cooling (both cooling and heating)- pilot pioneered by CSIRO
begins with a typical solar hot water system. A portion of that hot water would
be diverted into the solar AC unit, which is divided into 2 compartments. The
hot water enters a heat exchanger in the first compartment (similar to a car
radiator, the heat exchanger uses the hot water to heat outside air that has
been drawn into the first compartment through the vent.) At the same time,
outside air is being drawn into the 2nd compartment into a “dessicant
wheel” which dries out the air, cooling it down before being released back into
is required, the hot air is instead used to directly warm the house.
If there is no sun or heat to
drive the dessicant wheel process, you can mitigate this intermittency by
switching into indirect evaporative cooling mode.
systems require some electricity from the grid in order to operate: the conventional
Solar Powered Cooling System uses it to power the compression and circulation
of the refrigerant gas, and the open loop cooler uses it to power the cooler
for the incoming air. With either, you’re drawing less power from the
electricity grid, and will therefore use less electricity when you utilise
solar air conditioners – provided the unit you invest in isn’t
particularly energy inefficient.