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    • CommentAuthorGavin_A
    • CommentTimeAug 29th 2011
     
    Posted By: JSHarrisThe same is true for all schemes that attract government grants or payments.

    well you'd think so, but the evidence from clearskies / low carbon buildings programme grants says otherwise, as prices barely dropped at all through it's 4 years or so of operation, and the installer base barely changed either.
    •  
      CommentAuthorSteamyTea
    • CommentTimeAug 29th 2011
     
    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.
    •  
      CommentAuthorJSHarris
    • CommentTimeAug 29th 2011
     
    I'm a bit sceptical about the 20% PV performance improvement, to be honest, as we've already established that, because of the very large heat exchanger area, the delta T of the heat pump only needs to be quite small, so the cooling effect on the PV panels will similarly be quite modest.

    PV efficiency drops by around 0.5% to 1% per deg C (depending on the particular cells used), so to gain a 20% improvement the panel temperature needs to be around 20 to 40 deg C cooler than it would be without the heat pump running, but the solar panel area is significantly larger than might be the case for a solar water system, at the quoted 25m².

    The heat pump will have to shift a lot of heat to lower the panel temperature by 40 deg C; even lowering it by 20 deg C is going to be a challenge I'd have thought.
    •  
      CommentAuthorJSHarris
    • CommentTimeAug 29th 2011 edited
     
    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.
    • CommentAuthorsimmo
    • CommentTimeAug 29th 2011
     
    I have also been very seriously considering the New Form Enery PVT PowerTherm panel but can only accomodate a 12 panel array. this is not adequate to integrate with the heat pump so I am very concerned that the DHW generated may not be hot enough to be of much use.

    I am strongly considering reverting to plan A with separate PV/ solar thermal.

    Any thoughts?
    •  
      CommentAuthorSteamyTea
    • CommentTimeAug 29th 2011 edited
     
    Posted By: simmoAny thoughts?


    let someone else take a chance on it, stick to tried and tested.
    • CommentAuthorJoiner
    • CommentTimeAug 30th 2011
     
    Yup. Trial and error is for the rich and the heavily subsidised and academics with a sinecure at a well-endowed college. :shocked:
    • CommentAuthorowlman
    • CommentTimeAug 30th 2011
     
    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.
    •  
      CommentAuthorDamonHD
    • CommentTimeAug 30th 2011
     
    I do hope to do a little solar thermal when we upgrade to a heat-pump, and I'd like that to be PV/T, but we'll only have 2--4m^2, so not enough for anything hugely fancy. And that heat-pump upgrade is going to have to wait for RHI to get sorted and the market to mature a little, so not for a while unfortunately.

    Rgds

    Damon
    • CommentAuthordpaddym1
    • CommentTimeSep 2nd 2011
     
    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/
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 2nd 2011
     
    Thanks 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.
  1.  
    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.
    • CommentAuthorsimmo
    • CommentTimeSep 2nd 2011
     
    With ref to MarkBennett's posting, i think that is exactly what New Form Energy offer
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 2nd 2011
     
    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.
    • CommentAuthorSteveZ
    • CommentTimeSep 6th 2011
     
    My apologies for contributing to the drift away from the original topic of Energie Thermodynamic Panels but you might be interested in this PV-T+ Heat Pump news

    The Stove Shop in Liskeard (Cornwall) has been in touch and tell me they have a NewForm Energy installation working at their shop and have also recently completed another installation in Cornwall. At the moment, there does not appear to be any mention of this on their website itself, but if you are looking to see one in action in Cornwall, no doubt they would be happy to demonstrate how it works.

    I have no connection with either company, apart from my original enquiry about the NewForm Energy system.
    •  
      CommentAuthorSteamyTea
    • CommentTimeSep 6th 2011 edited
     
    Maybe I should get myself along to the bad end of the county and see for myself. Be interesting to get some hard data.
    •  
      CommentAuthordjh
    • CommentTimeSep 6th 2011
     
    What's the appropriate figure of merit for the PV-T panels plus heat pump system?

    For example: How much electricity do the panels produce and how much does the heat pump consume? How much heat does the heat pump produce and how does that compare with an equivalent area of conventional solar thermal tubes? And how do costs compare?

    Are example numbers around anywhere?
    • CommentAuthorGavin_A
    • CommentTimeSep 6th 2011
     
    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.
    •  
      CommentAuthordjh
    • CommentTimeSep 9th 2011
     
    Posted By: Gavin_A
    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.

    Thanks for that. I've now had a chance to read everything I can see on the site. I'd like to believe in the product because it seems a good combination and because you apparently believe in it but at the moment I can't suppress my snake oil hackles.

    There are too many numbers missing in the details for me to be sure I've understood exactly what they're reporting, and there are several discrepancies in the numbers that are there. I hope it's all just mistakes and that they will correct them and fill in the gaps but unless they do, I can't convince myself that it all works as advertised.
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 9th 2011
     
    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
    • CommentAuthorGavin_A
    • CommentTimeSep 9th 2011
     
    well, I'm off on a training day for installing this stuff on tuesday, so should have some more info after that.

    FWIW, I'm very sceptical of ASHP, and very sceptical of standard PVT, but combining the 2 just makes logical sense to me, as I'm sure posts on here from me last year about the original PVT systems would show. I'm not seeing this as some magic cure to all the worlds ills, but think it 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.
    •  
      CommentAuthordjh
    • CommentTimeSep 12th 2011
     
    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.
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 12th 2011
     
    djh: Not only do I get 'enough' solar thermal (and I'm not sure that I could accommodate ET in my remaining sub-1m-strip of roof space anyway), but I also get some useful extra electricity, which I can use grid-tied or off-grid (these panels have a suitable Voc for my 12V system and common solar controllers).

    Rgds

    Damo
    •  
      CommentAuthordjh
    • CommentTimeSep 12th 2011 edited
     
    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? :bigsmile:
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 12th 2011
     
    Realistically, given the incidence of sun on my east- and west- facing roof surfaces, and the space available on them, and given that I don't want a thermal system to boil mid-summer, probably not.

    If I had space for a huge thermal store (20t--40t+) and about 5 times as many panels then I could possibly ditch gas entirely for DHW *and* CH. As it is I'm contemplating a 2t thermal store to stretch the DHW season a month or so and reduce summer overheat risks, but that would require a lot of messing around difficult to justify on 'embedded' energy grounds.

    Rgds

    Damon
    •  
      CommentAuthorSteamyTea
    • CommentTimeSep 12th 2011 edited
     
    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.
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 12th 2011
     
    I don't have to do it all in one go in any case...

    Rgds

    Damon
    • CommentAuthorGavin_A
    • CommentTimeSep 16th 2011
     
    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 £20-25k installed rather than the £25-30k 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.
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 16th 2011
     
    Did you manage to find out anything about the PV efficiency improvement claim from cooling the panels, by any chance?

    I'm a bit sceptical that the PV elements will be cooled enough by the HP to make a noticeable difference to their efficiency, based on the amount of heat that would need to be pumped from them to keep them cool and the problem of where to store all the resultant heat energy through the day.

    Apart from that, it's a good solution in terms of collocating the solar heating and PV elements on to the same bit of roof space, which may well be advantageous for those with limited roof area facing in an appropriate direction.
  2.  
    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/
   
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