Thermodynamic Solar Panels

[fred]

How effective are these ? Are they much of an improvement over the old types ?

[Tim Streater]

What are "Thermodynamic Solar Panels" ??

[dkol]

[Bob Minchin]

I would imagine you can get a bit more energy transfer but a much more complex system. Once the panel has got frost on it then that acts as an insulator and the efficiency will drop off until the frost has melted. I have solar thermal tubes and these do very well for 7 months of the year giving me most of the hot water I need. The remaining 5 months the gas boiler runs for about 15 mins twice a day for DHW. I suspect the improvement offered by thermodynamic panels would have a much higher capital cost and only save a bit of gas and you still need the power to run the heat pump. All my system needs is a central heating type pump and temperature difference controller consuming a watt or so.

[Max Demian]

Not if the "old types" are PV. ;->

[Brian Gaff]

So how is this any different to the hot water heaters for roofs that many already have. A friend of mine has one and it seems to save money, but of course there is the capital outlay, the need to keep them clean and any possible issues when they go wrong.

Brian

[charles]

On some newish houses in this village, hot water creating panel were fitted on the roofs. But they hadn'r been fitted properly. When it snowed all the panels were completely clear - the snow melted off them!

[Andy Burns]

I see comparisons where the payback for gas vs thermodynamic hot water is 30 years, so they make it look justifiable by assuming the boiler needs replacement after 15 years, they seem to assume the thermodynamic system won't need replacing inside 20 years.

But then, their understanding of power vs energy is summed up by "uses

360 watts an hour"

[invalid]

Because its a heat pump it can work in the dark, but you get better efficiency when the sun shines on them.

If you just want hot water then normal passive solar panels are somewhat easier.

[newshound]

Maybe that is what you want, once they are clear of snow they stand a chance of picking up some solar heat. And presumably you don't want them freezing. I wonder if a smart heat pump system would manage this automatically?

[Martin Brown]

It is able to take more low grade heat but at an enormous increase in complexity and plenty of moving parts to go wrong. I'd expect price performance to be risible (much like with ground source heat pumps when you include all the capital costs and ongoing maintainance work needed).

What is the payback period for your thermal solar tubes?

Presumably one of the variants that uses a heat pipe in a glass tube silvered on the back half and plugged into a manifold.

[fred]

Given all the above would photo electric panels (or whatever they are called) be more cost effective ?

[invalid]

They were better because you got a lot of payments for the electricity even if you used it all yourself.

As for being green then passive solar water heating is probably greener than solar PV.

[invalid]

Doesn't need to. My solar hot water never get lying snow on them and they are installed correctly. The glycol stops them freezing.

[newshound]

So the angle and surface finish stops snow settling? Always? Do you perhaps have a "cotswold" slope?

[Bob Minchin]

Without RHI the payback calculations would make it a total non starter. My basic capital costs of the solar thermal are covered by the RHI. I did a one day training course for around £200 enabling me to do the installation myself and get it MCS certified - mandatory in order to get RHI. I did it as an interesting retirement project together with a PV dumping diverter - home made. The overall project has covered its costs over 6 years and now is in profit after all my household energy has been paid for.

Yes exactly that. An array of 30 vacuum tubes each with a water based heat pipe.

[invalid]

about 30 degrees

[alan_m]

The figures assume that the panels generate enough hot water for the average family 365 days a year without any need for a top up from any other source.

Reference their "unit" figures why would an electric boiler be 12 pence per kWh and an electric immersion heater be 30 pence per kWh?

Quote thermodynamic water heating systems may cost over 10 times less to operate than other common types, such as electric immersion heaters /Quote

It's only 10x because they have used the wrong figures and so their quoted break even point of 5 years is some what bogus.

As for boiler replacement, wouldn't it still be needed for central heating and if so the ability to also provide hot water comes for free (or just for the cost of the fuel).