Should I buy thermodynamic panels?

Thermodynamic panels are a form of renewable heating. They basically work similarly to air source heat pumps, but are less bulky and don’t require fans.

The panels work by circulating liquid coolant which absorbs heat from the atmosphere and turns it into gas. The gas then goes through a compressor, which boosts its temperature so that it is hot enough to heat water. In theory they take the best elements of solar thermal and heat pumps and pull them together into one technology.

If you know how your fridge works, imagine that in reverse and you’ll get the general idea…

The theory behind thermodynamic panels

The technology hinges on the difference in temperature between the coolant and the air around it. Because the refrigerant going round the panel is at a very low temperature of between -20°C and -30°C, it can absorb relative warmth from the air even on cold days.

The water reaches a max. temperature of 55ºC, meaning it can be used for showering, swimming pools or to supplement central heating. Systems include a built-in immersion heater that occasionally spikes the water temperature to 70ºC to kill off bacteria such as Legionella.

Unlike solar PV or solar thermal systems, these panels are apparently unaffected by weather. Proponents claim they heat just as effectively in windy, wet or freezing weather as they do on hot or sunny days. Thermodynamic panels are normally installed on a roof or a wall, so they can be fairly discreet, unlike bulky heat pumps. Solar gain will help their efficiency, but the panels are designed to work without it, so the direction the panels are facing is not an essential consideration.

The reality of thermodynamic panels

Thermodynamic panels sound like a pretty exciting development – but do they live up to hype? Claims of free, clean, unlimited energy currently seem unsubstantiated.

Most manufacturers suggest that one or two panels will be sufficient to heat sanitary water for a family of four. Each panel costs £5000 to buy and install, so not cheap. It’s also hard to accept that the hot water they produce is ‘free’ when you consider that the compressor runs on electricity. Electricity costs for a domestic system are estimated at around £8 to £10 per month.

Thermodynamic panels have been around for a few years now, and it’s tempting to suggest that if they were all they were cracked up to be, they would have been more widely adopted by now. One issue is that they are pretty complicated, and complicated equipment tends to go wrong more often, and be more difficult to fix. When it comes to home heating, reliability is very important, and unreliable systems are going to fall to the bottom of the pile when it comes to a customer choosing to buy a new system.

The basic idea behind the technology makes sense, but studies have been somewhat underwhelming when it comes to results.

What is the future for thermodynamic panels?

There were hopes that they would qualify for the Renewable Heat Incentive, which pays homeowners for installing renewable heat technologies. Although RHI rates are not as high as they were, the scheme is still an incentive and a reassurance for those installing systems included in it.

Thermodynamic panels have not been made eligible in the latest wave of changes to the scheme. The fact the Government does not recognise the technology doesn’t reflect well, as it suggests a lack of belief in the benefit of thermodynamic panels for homeowners.

The bottom line is that there is currently no clear guarantee of their performance, so we would maybe suggest waiting for this before adopting the technology. The systems need to make financial sense without Government funding, because – as adopters of solar PV have found out – this cannot be relied on.

Who knows what the future will hold for thermodynamic panels? Maybe with some refinement they could become a viable heating option. Have you had one installed? If so, comment below and let us know your thoughts!

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