I’ve been sent a scan of a one page article in the Clean Slate publication by the Centre for Alternative Technology (CAT, www.cat.org.uk) that has the title:
Think Twice about thermodynamic panels
Compared to an air source heat pump, a Thermodynamic panels is a heat pump connected to a flat panel instead of the heat exchange unit.
The article is concerned that:
- Panel collectors might work well in some conditions, but badly in others.
- That air flow can be poor around them,
- That they can ice up.
- That there are no studies on year round performance to back up marketing claims.*
- They don’t qualify for the Microgeneration Certifciation Scheme (MCS). So, pending any updated clarification as what they are (heat pump?) they won’t qualify for the Renewable Heat Incentive (RHI).
* I’ll have to check, but a few companies and Internet sources do seem to have put their year round data on-line. OK these aren’t independent studies, but there is data about.
If the panel is running at low efficiency, then you have a low or zero coefficient of performance or COP. The article points out that consequent running costs at such times could be more expensive than gas (or even oil).
The report quotes an “Energie” thermodynamic system consuming 4.1 kWh of electricity to heat 250 litres of water from 10°C to 55°C with 15°C ambient temp. The 2.7 COP is “no better, financially or environmentally, than a modern gas boiler).
They say a conventional solar water heating system would use less energy and so cost less. The report references the Energy Saving Trust field trial ( I Google found the link).
The reports concern is that:
- In winter a boiler would be more cost effective.
- In summer a conventional solar water heating system will be better.
A conventional solar hot water heating system uses almost no fuel.
The CAT advice sheet on conventional solar water heating systems is here.
Confused Conclusion for Silver Spray Water Heating
The end solution for Silver Spray isn’t clear.
- No mains gas.
- Next to the sea (so an air source unit will fail and need major component repairs and replacement within 5 years.)
- Cliff top and narrow plot, plus slope etc means ground source by buried pipes or vertical drilled holes both seem unrealistic.
- There are going to to solar elec PV panels.
- The house is going to be highly insulated and sealed, so there will be a low space heating requirement.
So if Thermodynamic panels can have a good chunk of their winter electricity from the PV panels, they could still be the best solution.