So for this system to work effectively we a now talking ground loops and inter-seasonal stores are we. Would like to see the manufacturers/installers data.

Further to the above, I've just done some "back of fag packet" calcs, with some broad (and perhaps questionable) assumptions.

Assuming that the heat pump can keep the panel at ambient air temperature, so effectively removing heat losses, then a 25m² panel is going to deliver around 25kW to 30kW for a typical UK irradiation level with some very rough guesses at absorption factor. As I'd guessed above the system is going to struggle to keep the PV panels cool for any length of time, unless it's hooked up to a pretty big thermal store. Add in a 3:1 COP factor and the thermal store will need to be able to absorb around 33kW to 40kW during the time that the panel is exposed to full sun.

Posted By: simmoAny thoughts?

let someone else take a chance on it, stick to tried and tested.

Posted By: SteamyTea
let someone else take a chance on it, stick to tried and tested.

I don't have the cash anyway, but my thoughts too.

I thought it may be useful to reply to the original question regarding Energie Thermodynamic Systems and some of the points that were subsequently raised. Firstly I should state that I work for the N. Ireland distributor of the Energie system so have a vested interest and you will have to take my comments as you see fit! I will try and be as objective as possible.

The system is not new technology; it is basically a freezer “in reverse” and like a freezer consists of a heat collecting panel(s), refrigerant piping and an integrated electric heat pump. It is a clever application of well tried and tested technology that has been around for almost 100 years. The panels are made from weather protected anodized aluminium and are not vulnerable to extremes in hot or cold. They are light, weighing only 8 Kg and may be mounted in virtually any orientation or angle. It has been estimated that 25% of the energy absorbed by a panel comes from solar irradiation, the balance taken from air and rain. Both sides of the panel are available to collect energy. The company that manufactures the system is based in Portugal and to meet growing global demand they have just built a second factory reflecting their 25 year history of success with the product. You can check them out at http://www.energie.pt/?cult=uk

The Energie system is fully scalable from 1 - 2 panels for domestic hot water, to 4 – 24 panels for central heating right up to 40 panels for large volume hot water requirements. Note that additional panels simply mean faster water heating times, not higher water temperature which is set to between 55 and 60 C maximum. A typical domestic installation for domestic hot water will have a 250L cylinder with a single panel mounted on the roof. The heat pump is integrated directly into the Energie cylinder so an existing hot water cylinder cannot be used in this configuration. For central heating and large volume hot water requirements the heat pump (Solar Block in Energie speak) is a stand-alone device. Energie cylinders are either stainless steel or enamelled steel and can come with an additional coil for connecting into a backup heat source if desired. Sizes range from 200L to 6,000L.

All Energie Thermodynamic Systems are accredited under the MCS scheme.

A question was asked about the refrigerant (the system uses 407A) and if it would need topping up. The simple answer is no, like your freezer this is not required. The only maintenance may be the occasional replacement of the sacrificial anode in the cylinder should you live in an area with soft water.

Another point raised concerned the panel frosting over in winter. This is possibly best addressed by personal experience. I installed a 300L single panel system in my home at the start of this year, and although there was some frosting in the very cold weather at that time on the top surface of the panel, the bottom side was clear, and we always had enough hot water. Eight months later we have never had call to revert to either our central heating boiler which has been turned off these past 5 months, or the small integrated immersion that comes with the Energie cylinder. I estimate from measurements I have taken that the Energie system has used an average of 3.6 KWh of electricity per day over the 8 months January to August for our 4-person household at a COP of just over 3.

Hundreds of Energie systems have been installed successfully throughout Ireland over the last 4 years and having come through last winter are well tested for the vagaries of the UK and Irish climate.

Finally some additional information as supplied by Energie can be found using the link below.
http://www.e3renewables.com/downloads/

Posted By: JSHarrisThanks for the input on the heat pump side of this system, your comments broadly align with what should be expected in terms of performance for a relatively large collector ASHP, with direct solar augmentation.

I think that some of the concerns raised in this thread relate to the improved PV performance from running the panels at a lower temperature, particularly during periods of high irradiance (i.e. bright sunshine). There seems to be a claim that PV performance will be improved by a significant percentage (20% has been quoted), yet this big an improvement requires a large amount of heat to be pumped from the panels all the time the sun was shining; more than even a reasonably large thermal store would be able to accept, I believe.

It's this latter point that concerns me, as I can't see how the system can keep a large (25m² has been quoted previously) PV array cool enough to gain the quoted efficiency gain.

Be careful not to confuse the Energie system with PV-T - they are quite different.

The Energie system is effectively an air source heat pump but using roof mounted collectors instead of air pumped through a heat exchanger. There is no electricity generation as a part of this.

PV-T are panels combining PV and solar thermal collectors - no heat pump technology at all.

The only similarity is that they both produce hot water.

I'm not aware of anyone doing a combined PV/Thermal solar/heat pump system.

Indeed, it was the combined ASHP/PV system that we had been discussing in this thread, and which I assumed dpaddym1 was referring to, that I responded to.

I still believe that it will be hard to dump enough heat from the panels to make a worthwhile improvement in PV efficiency, unless a very large capacity thermal store is used.

Maybe I should get myself along to the bad end of the county and see for myself. Be interesting to get some hard data.

Posted By: djhAre example numbers around anywhere?

several of the example installs on the website have figures for total gross and net annual electricity and heat production. Not entirely clear if they're predicted or actual, but I think they're actual as at first glance it looked like only the older ones had the figures.

I've had a detailed quote from NE, though not involving a heat-pump since I don't have enough uncommitted space: NE seems entirely legit and sound from my back and forth with them and not claiming anything that doesn't seem supported by numbers I know from elsewhere.

With even the remaining space that I have (<8m^2), 4 of the PowerTherm panels (optimised for heat collection rather than electrical generation) could entirely eliminate gas use for DHW for us for 4+ months of the year by the looks of things (with a 200l+ thermal store and Grant CombiSOL or similar to work in conjunction with our existing combi). Plus I'd generate about another 0.5MWh/y electricity.

Rgds

Damon

Posted By: DamonHD4 of the PowerTherm panels (optimised for heat collection rather than electrical generation) could entirely eliminate gas use for DHW for us for 4+ months of the year

What benefit do they offer over regular evacuated tubes? As I understand it, their thermal performance will be significantly worse.

Posted By: Gavin_Ait ought to be capable of being a small but useful part of the low carbon energy picture if used in the correct way in certain situations

Yes, it's trying to understand what the certain situations are that I'm finding difficult.

Posted By: DamonHDentirely eliminate gas use for DHW for us for 4+ months of the year

Posted By: DamonHDdjh: Not only do I get 'enough' solar thermal

Isn't there scope for getting rid of gas usage for longer than 4 months? i.e. how do you define enough?

Posted By: DamonHDdifficult to justify on 'embedded' energy grounds

All depends how long the system is used for. Easy enough to work out the embedded energy/CO2.

the course was interesting, the system looks like having potential, but it's still in it's early stages really, with the first installation only completed last december, so not even a full years figures to work from. It's all a little bit heat robinsonesk right now as well.

Phase 2 looks like being a bit better, ironing out some of the issues and adding a better controller etc which should be available this winter.

They're installing a huge system at grand designs blokey's house combining 48 panels, 3 heat pumps, and a big ground loop.

they're also looking to drive the prices down fairly swiftly once they ramp up production / get better bulk discounts on the panels etc. and apparently the current price is nearer Ă‚ÂŁ20-25k installed rather than the Ă‚ÂŁ25-30k I mentioned earlier.

I still think the major use for this system is going to be in combination with a small ground loop, which can be used to generate heat better in the worst of the winter, but can be a lot smaller than standard as it won't be used as much, and can be topped up / recharged to some extent from the panels on days of full sunlight. So probably not a mass market thing, but a good niche product for certain situations.

WoW, what a thread.

I was looking for more info on the Thermodynamic Panels I saw at the EcoBuild show.

I've also spent a chunk of time at the show trying to nail down the PVT versus PV or PT argument.
- it very ties in with what is said here. That fundmentally the optimum temp for PV and PT are a long way apart, so you kill one or the other if you combine them.

I did see a flat roof tilting racks sytem at the show, that is apparently designed to help "green roof" planting around the panels (for PV) so that you can keep them a bit cooler.

My own notes (so far) on both topics are at:
- http://www.silverspray.co.uk/2012/03/27/ecobuild-photovoltaic-pvt-vs-pv-or-pt/
- http://www.silverspray.co.uk/2012/03/27/ecobuild-thermodynamic-panels-heat-exchanger/