thermodynamic panels

[JimK]

anyone got em yet? any good?

Jim K

[Tim Streater]

Hard to say, although the adjective "thermodynamic" is meaningless as applied to these panels.

[Martin Brown]

Actually it is very indicative of a liberal application of snake oil.

Caveat emptor!

[Andy Burns]

£5500 to install plus 33p/day to run, vs sticking with my 60p/day to run? It might be nice to think I'll live the 57 years to break even, but ...

[JimK]

questions+answered/

what do you get for 60p a day though?

Jim K

[fred]

In article , Martin Brown writes

If that stuff leaks out it can make a hell of a mess of your carpets :-/

"Having heard quite a few outrageous claims made for these panels at trade shows last year, my advice would be for buyers to be wary of investing at this stage, until there has been some testing in the UK, and standards for performance are set by MCS."

sounds like a good summary.

[Andy Burns]

Traditional H/W tank heated twice a day, one of which will generally be a minimal top-up, their system might be sized for showering a couple of teenagers I suppose ...

[Bob Minchin]

PV panel efficiency drops off with increased panel temperature. Standard PV panels are normally mounted a few inches off the roof surface where natural convection currents help cool the back of the panel. Putting a solar thermal panel behind defeats this. By the time the thermal part of the panel is up to a useful water heating temperature say 80c or more, the efficiency of the PV is well down the slippery slope.

Also the proportions are all wrong. For a domestic installation, 10-15 sq m of PV is about right but you only need a solar thermal aperture of say 2sq m to get more than enough hot water.

[Andy Burns]

The way I read it, there's nothing photovoltaic about them, they're a heat-pump version of solar water heating panels ...

[Bob Minchin]

Yes Apologies, I jumped to a conclusion that they were the same as I saw at an exhibition last year.

I don't think these have anything to offer. I have 30 x 58mm evacuated tubes (about 2 sq m) and a 357 litre store. I collect so much from this system that in peak summer, I'm sending excess heat to bathroom towel rail once the store has got to 93 degrees C

[Alan Braggins]

Many many years ago I read a book which said heat pump plus solar was the most efficient heating system, but the capital installation costs made it impractical. It's got somewhat cheaper since, and the principle is still sound, but the vendors do seem prone to hyperbole.

Bob's objection sounds more like hybrid ("PV-T") panels. cf.

"It is possible to imagine a solar heating application which would keep the temperature lower for more of the day. For example PV-T panels heating water in a swimming pool would operate at 30-40 degrees all the time." Since I have a swimming pool with a failing gas heater....

However, there is an obvious connection between heat pumps and hybrid panels - the PV part of the panel will be more efficient at temperatures which are lower than you want for hot water. But if you use some of the PV electricity to run a heat pump, you can have panels producing luke warm water, and the output of the heat pump producing hot water (i.e. same as the "thermodynamic" panels, but with added PV, in less roof space than separate "thermodynamic" and PV panels, and with the PV cooled for better efficiency).

You can even make the initial system cost even higher, by combining it with a ground source heat pump, and using surplus solar heat to warm up for subsoil to be recovered at night, or even in winter..... e.g.

[meow2222]

estions+answered/

"How much hot water do they produce?

They claim to provide 100% of the hot water requirements for domestic and c ommercial premises, swimming pools, underfloor heating and can make a contr ibution to traditional central heating. They come with a built in immersion which uses electricity to boost the water to 60 degrees every so often to avoid any risk of legionella."

anyone spot a slight contradiction?

NT

[Tim+]

Yes and no. Isn't an immersion for legionella eradication good practice and fairly normal for cylinders running as sub-60 temperatures most of the time?

Tim

[dennis]

I am not convinced that you need to run at a high temp in a sealed system but they tell you that you should. If it were true then the chlorine in the pipes wouldn't make tap water safe either.

[Andrew Gabriel]

I considered a few things for hot water, until I eventually collected enough data to show that the spend on hot water heating was negligable compared with central heating, and nothing would ever pay back the investment.

I'm not convinced legionella eradication is a good idea. Exposure to it whilst you are healthy generates immunity. It only started to become a problem when we started trying to create super-hygenic water systems, which may have prevented regular exposure and immunity for some people.

[charles]

As someone who has suffered from legionella, I'd say you don't know anything about it. Exposure, when you are healthy results in a severe fever from which many people die; I know that my lung capacity was permanently reduced by over 50%. Future immunity is not guaranteed; I certainly wouldn't want to risk getting again.

[Fredxxx]

I understand immunity can last up to a year.

But most people are unaffected by Legionella, and seemingly only affects those with a poor immune system such as the old. Healthy people are generally unaware they may have the disease.

[JimK]

/....system that in peak summer, I'm sending excess heat to bathroom towel rail once the store has got to 93 degrees C /q

Sounds useful....

What do you get out of them in winter when you really need all you can get?

Jim K

[JimK]

/The way I read it, there's nothing photovoltaic about them, they're a heat-pump version of solar water heating panels ... /q

Precisement

Jim K

[charles]

I wasn't old when I got it, which is probably why I recovered. The outbreak that affected me also killed 3 people and seriously affected one of my colleagues - he is younger than me. Legionella is a particularly nasty variant of pneumonia which does not respond to regular antibiotics.