Solar thermal air conditioners a "gimmick", finds government testing

Models pulled from sale in Australia.

Powering an air conditioner using the sun might sound like an ideal way to lower electricity bills, but a new report has found some solar powered air conditioners cost more to run.

The Department of Environment and Energy tested two types of solar-powered air conditioning systems in 2016. One category failed testing and was subsequently removed from sale in Australia.

The two categories tested include solar thermal and solar photovoltaic air conditioners. Unlike solar photovoltaic (PV) air conditioners, which convert sunlight captured by a solar array into electricity, thermal systems use the sun's heat to turn an electric generator.

All three of the solar thermal air conditioners failed to pass the department's testing. None passed the Greenhouse and Energy Minimum Standards (GEMS) standard for heating and cooling and, worse yet, all three operated between 4% and 21% less efficiently with the solar power technology enabled.

The report slammed solar thermal boosting as "a marketing gimmick that offers no improvement in the performance or amenity of the air conditioner".

"As a result," it continued, "these models can no longer be supplied in the Australian market."

In 2012 CHOICE tested a solar thermal air conditioner and found that it wasn't any more efficient or better performing.

The photovoltaic air conditioner, by comparison, passed all of the government department's tests, delivering "significant improvements in efficiency".

But it had its own drawbacks. Using solar energy proved advantageous until the air conditioner operated at 75% of its solar array's capacity, where it became 'unstable' and would switch between solar and mains power.

A lot of stored electricity is wasted by PV air conditioners, the report found. A solar air conditioner will only use the energy it captures when it's in operation during the daytime. Energy captured would be wasted otherwise as it can't be used to power different household appliances.

There are two easy things people can do if they want to run a household more efficiently, says Chris Barnes, head of household at CHOICE.

"Most households will be better off in the long run by buying an efficient air conditioner with a high star rating.

"But if you want to reduce your electricity consumption further, look at installing a solar PV array."

See our reviews of small air conditioners, medium air conditioners and large air conditioners – or if you're thinking of going solar, see our solar panel reviews.

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