Looks like it's a heat pump with a solar-assisted air to liquid heat exchanger on the outdoors end.

This sounds like a good idea. Coupled with a well-insulated, fairly high thermal mass building it should be possible to gain enough heat during daylight hours to sustain demand through the evening/night, as well as provide DHW.

It also has the advantage of not needing (potentially noisy) fans, which is one thing that has put me off using an ASHP.

The only potential problem I can see is the possible need for periodic recharging with refrigerant, although this is probably no worse than that needed for something like an air conditioning system.

How does this technology stand with MCS and SAP?

we're about to start installing new form energy's PVT / Heat pump systems. Somewhere on here there's a thread about PVT panels from a year or so ago where I said I didn't see the point unless they had a heat pump attached, now someone's done it, so we'll now be able to offer 4kWp solar systems which generate approx 15-20% more electricity per year, plus hot water all year round, and maybe something like 50-60% of the household heating.

I reckon these systems will work very well for use with either a small ground loop for the heat pump, plus a big buffer tank, and biomass boiler for the peak heat demands in the depths of winter, with the heat pump supplying most of the heat the rest of the time.

Posted By: JSHarrisI'll be very interested in seeing how this works out, although using a biomass boiler seems odd, in light of the non-sustainable nature of burning biomass for heat.

yeah, but that's only perceived wisdom according to this forum, rather than reality, so I'll not worry overly about that other than specifying high efficiency, low polluting gasifying log boilers.

anyway, let's keep at least one thread on topic eh.

Posted By: JSHarrisHow many acres of woodland are needed to heat a single house, assuming that the wood is sustainably managed? Is it realistic for every home to own and manage such an area of woodland? No, is the simple answer.

you're making the same basic mistake that lots of people here seems to make.

nobody I'm aware of has ever seriously suggested trying to heat every home via biomass, and making that point on a thread where we're discussing solar/air sourced heat pumps as a source of heating is particularly odd.

UK heating is currently supplied by gas, oil, electricity direct and via heat pumps, and to a small extent coal and biomass. In future biomass will hopefully move up that list a bit, probably mostly replacing oil, and electric, and probably matched in varying degrees with solar water heating, and heat pumps, with the biomass providing top up heating.

Biomass is (or at least can be) a sustainable fuel source when used as a part of the overall mix of available lower carbon fuel sources, in situations where it is sensible to use it - ie mostly in the countryside in areas where local fuel supplies are available, and for the time being at least, where mains gas isn't.

I dont know about anyone else but I'm interested in the new thermodynamic panels and how they work in practice, not another rant against biomass, which incidentally confuses domestic and commercial biomass. Please can the thread stay on topic. Start another thread if that is what you want to discuss.

Presumably installers would have to be MCS accredited in all three disciplines,- more upfront fees for the workers? I've only just nicely got the PV installed and about to start the ST and along comes this, and the goalposts start to move again, "C'est la vie".

Guys, we are currently getting pricing for 4KW PV system and Solar System and one of the installers suggested these combined PVT pannels as the better approach. He didn't mention anything about heat pumps though, we have gas boiler and are going to have a thermal store and I assumed the water heated from the PVT panels would simply heat the ST in same way as tradditional solar but is the issue that the return temp from the panels is much lower? Would we have to have a HP or they just suggesting its an option for complete heating solution?

The statement "The chart above shows PowerVolt panels absorbing energy at -10°C in the dark, meaning that the system will perform at higher efficiencies than air-source heat pumps in similar sub-freezing overnight conditions.". Can someone explain this? Why will the panels provide anymore heat in the dark @ -10°C than an air source HP?

I don't like the idea of installing such a new technology, although I guess its just a combination of very established and proven technologies!

Phil - without the heat pump the PVT panels will need to operate for a large part of the time at 50-70 deg panel temps in order to get the water in the tank up to 60/65degrees. This means any improvements in PV performance will be negligible / only apply for small parts of the day.

Combining it with a heat pump will mean 55/60 deg water temps can be gained from 25 deg panels temps (or lower), meaning the PV panels can operate at or around their actual rated output in full sunlight rather than losing 15-20% of their output (due to ~0.45% per degree loss in performance of crystalline PV panels)

steamy tea - separating the systems out would mean the PV system didn't benefit from the cooling effect, so I'm not sure where you're coming from with that idea.

These systems will not be suitable for all situations, as apart from anything else, the amount of heat that can be delivered from them in summer is way in excess of a standard households hot water demand (depending on the size of the system of course). that said, if you use the uninsulated version it ought not to make much difference to the PV panel temp when not running, so it would still be beneficial for the time it's operating, just not as much so overall compared to situations with high levels of year round heat demand.

JSHarris - I agree that the benefits in minus outside air temps will be largely down to the no/minimal defrost cycle. In an ASHP the defrost cycle is needed more to prevent the air intake/exhaust actually freezing up, and the fan and other moving parts getting iced up. None of this applies the a PVT so long as it's above the glycol's freeze protection levels it'll be fine (though icing up of the heat fins will impact on the performance of the system).

The system's also not really being sold as something that's supposed to be capable of doing the houses entire heat load, more something that can do the bulk of it for much of the year, but will need a secondary heat source during the coldest periods. Hence matching with biomass, and / or a small ground loop for the heat pump (potentially with summer heat being pumped into it if ground conditions allow), or the existing oil / gas heating system.

Whilst I can understand that this system doesn't have fans etc to ice up, any ice on the heat exchanger will dramatically reduce it's performance, as ice is a pretty good insulator. This will present a problem at outside air temperature significantly greater than zero, as the heat exchanger will always be operating a few degrees cooler. A damp day with an outside air temperature of maybe 4 or 5 deg C would be enough to get the heat exchanger seriously iced up from condensation or frozen rain I'd have thought, yet they seem to be claiming that it still works OK down to -10 deg C, which I find a bit of a puzzle.

I still think it's a potentially good solution though, particularly if combined with good thermal storage. Pity about the price tag though, £30k is a heck of a lot of dosh and will put it out of reach for many, even with the current level of FITs subsidies.

I think you've heat the nail on the head mentioning the large evaporator heat exchanger area. That would allow the system to run with a much lower delta T than would be typical for a conventional ASHP, so reducing (but not eliminating) the icing problem.

It's such a shame that DIY projects cannot be taking advantage of FIT's have you all noticed how prices have skyrocketed through MSC accreditation requirements which is not good for those clever DIY people who want to save money and do things as cheap as possible.

Maybe i'm wrong but all these stitch up regs are great for those who want to make money but not those who want to save it. I know there is a market for specialists but you don't have to use most of them if you don't want to throughout your build but some things you have no option and its mostly there to stop DIY people having fun.

Obviously the final connection to the Grid has to be correct but as long as the circuits are protected correctly against faults which after all can occur in specialist equipment, whats the difference.

What would happen if you got an MSC company to install 1Kw of solar PV and then you as a DIY man added your own home made panels to the curcuit to increase the output?

just a simple query lol

Panels are coming in at about £1/Wp now, have inverters dropped much?

Posted By: SteamyTea

Posted By: Gavin_Asteamy tea - separating the systems out would mean the PV system didn't benefit from the cooling effect, so I'm not sure where you're coming from with that idea

Think JSH is really asking the same questions. But if the HP is not running much in the summer, then where is the advantage of cooling the panel in winter.
Don't get me wrong, I like the idea, just think it is a bit complex for little or no gain, and at that sort of money you could buy a lot of insulation.
I would have to see real operational data as well as manufacturers data before I could recommend that. Is there any real data yet?

PV performance increases don't stop at 25 degrees, so a cooler panel in winter will still perform better than an uncooled panel (upto the point at which the cooling results in ice forming on the panel).

On days of full sun all day in summer, then I'd think the heat pump would only operate for a relatively small part of that time to supply hot water requirements for a house. However, these days are relatively rare, and the majority of the time in this country we only get a few hours of full sun, so I'd think that on average through the summer the heat pump would be operating maybe 50% of the full sunlight hours, during which time it will be improving output of the panels by 15-20%, and the heat pump efficiency will also be maximised even compared to an ASHP. For the rest of the year, the proportion of sunlight time the heat pump would be operating would increase.

Manufacturers are claiming around 20% increase in annual output from the PV panels, which I can see being possible in some circumstances (eg some of the systems seem to have either larger hot water requirements or goundloops for interseasonal heat storage. I'd expect somewhere in the 10-15% increase in annual output to be more likely for a family home.

The increases in performance of the PV is only one part of the story though, with another side being much higher COP's than ASHP, particularly for the water heating side of things, and the potential to be combined with a much smaller than usual ground loop to supply heat at night instead of/as well as the panels.

The 3rd aspect being that if combined with a decent sized thermal store, most of the heat energy can be produced when the panels are generating power, so you're not going to be paying for that energy source. Obviously you could achieve this with an air or ground sourced system combined with PV, but then you'd not be getting the additional 10-20% electrical output from the panels which alone could well supply maybe 1/3 of the heat pumps electrical requirements.