JackofAll Posted October 17, 2022 Share Posted October 17, 2022 Planning on using immersion/willis/ pv panels for heating water in new build. PV fitted with an eddi connected so was thinking the solar could get the water temp up to whatever first and immersion/s could finish off to desired temp. Has anyone done this? Link to comment Share on other sites More sharing options...
JohnMo Posted October 17, 2022 Share Posted October 17, 2022 You need to do your research, as the yield in winter is pretty rubbish. You will be able to do DHW in the summer , but maybe not the heating. Really depends on array size and how well insulated your are. Big array, you may be ok on a sunny day for a couple of hours, but would make sure your ok paying full price electric. Link to comment Share on other sites More sharing options...
Conor Posted October 17, 2022 Share Posted October 17, 2022 (edited) Better doing it in reverse. Set your main immersion coil to say, 45c, timed to overnight cheap rate. Then have your solar diverter powered immersion set to a much higher temp, say 60c. This setup means that on sunny days your tank will be heated up to 60c, and your overnight immersion won't be needed. Then, on dull days when you've less heating and maybe used more water than normal, the overnight top-up will ensure you'll always have hot water. If you ever run out during the day, then you'll have to boost your main immersion. We've a similar setup, but with an ASHP doing the overnight top-up to 45c. Even this time of year, our 4.5kW array isn't enough to heat the water sufficiently. Edited October 17, 2022 by Conor Link to comment Share on other sites More sharing options...
SteamyTea Posted October 17, 2022 Share Posted October 17, 2022 (edited) A system set to PVGIS's optimal angles would yield around 37 kWh/kWp installed, so around 1.2 kWh a day in December and January. Changing the slope angle to 75° would up that a bit to 44 kWh, so 1.4 kWh/day. The power, at any given time, would be pitifully low, probably peaking at 200 W. So the only real way to make use is to have a large array and battery storage. Once you have electrical storage, you can run a heat pump, which at that time of year may effectively double the output. But not every day some days will be better than others. You can get a bit smart by linking a control system to the Met Office (I think they have an API, @TerryE uses it I think) to help predict what you may generate, then use accordingly. All in all, it will be an expensive system, so may be better off thinking about getting a small CHP unit to supplement it. Best to work out your expected loads first, the lower they are the better off you are. My small (50m2) terrace house uses around 13 kWh/day in the winter, purely resistance heating here. I am hoping to get that down to 9 kWh/day this winter, but it is going to be harder that getting down to 13 from 25 kWh/day. Edited October 17, 2022 by SteamyTea Link to comment Share on other sites More sharing options...
jamieled Posted October 17, 2022 Share Posted October 17, 2022 We do something like that. The excess PV is dumped into an unvented cylinder and then I use the boost function on the Eddi to heat the water on days when there's not enough sun. As a rough idea, in summer I won't need to boost the water at all (odd exception) and in winter it might need 2-3 hours quite regularly. I like it for its simplicity and it doesn't seem overly expensive to run. There are cheaper ways of heating water, but they all have higher capital costs and it would need a much higher electricity price to convince me of changing the current setup. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 17, 2022 Share Posted October 17, 2022 2 minutes ago, jamieled said: a much higher electricity price to convince me of changing the current setup EDF are going to charge me 34p/kWh for night usage. 1 Link to comment Share on other sites More sharing options...
JohnMo Posted October 17, 2022 Share Posted October 17, 2022 1 hour ago, SteamyTea said: EDF are going to charge me 34p/kWh for night usage Wait till next April - they may want an arm and leg also. Link to comment Share on other sites More sharing options...
Iceverge Posted October 17, 2022 Share Posted October 17, 2022 Ball park guess looking at your house you'll use 6000 MWh of heating per year plus 4500kWh of DHW. Realistically solar@4kWp might give 3000kWh towards DHW mostly. 7500kWh left to make up. Electricity will probably be about 20c per unit so €1500. An ASHP at €4k to reduce your bill to €500 looks like a 4 year payback if you can self install. In fact forgoing the solar and paying for an ASHP makes more sense financially at least. Even with airtight+ super insulated houses cheap Willis only heating really depends on a good form facto( a 2-3 story box). Few + small windows (the window + window/wall junctions are poor thermally) and a small floor area. Link to comment Share on other sites More sharing options...
JackofAll Posted October 18, 2022 Author Share Posted October 18, 2022 Thanks lads for your replies.looks like I need to research more. From hearing some of the prices people are paying for A2W installed here I was like feic that, seeing the willis heater set ups some of you have installed was thinking that it's quite simple(like myself). Currently spend 4/4.5k a year on heating/electric, so circa 1.5k would be a saving. Link to comment Share on other sites More sharing options...
TerryE Posted October 21, 2022 Share Posted October 21, 2022 (edited) If you use a warm slab (See MBC website profiles), though other specialist builders do these as well, then your main thermal store is the slab itself. Willis-only isn't cost effective for new build with current electricity prices. Better to go for energy efficient build and ASHP direct into slab circulating UFH water at ~35°C so CoP should be around 4. A few there have done this very effectively. The issue you will have is getting an MCSE installer to do this for you because their standard templates don't work for such energy efficient builds. However you don't actually need to use an MSCE installer as this can be signed off by your Binsp, esp is you have a private one. You just need to do all of the calcs to prove conformance to BRegs Edited October 21, 2022 by TerryE Link to comment Share on other sites More sharing options...
Iceverge Posted October 21, 2022 Share Posted October 21, 2022 There's some new Mitsubishi ASHPs on donedeal at the moment for €1700. If you DIY install you're looking at less than a 2 year payback. Plumbers in Ireland are taking the proverbial with their prices. It was €7-10k extra for an ASHP for us plus fitting. I couldn't stomach the gouging. If you're any way handy the Hep2O plumbing system is childsplay. Even on our passive house payback would be less than 3 years. Not the 25+ it would have taken had we paid the plumbers. 1 Link to comment Share on other sites More sharing options...
ProDave Posted October 21, 2022 Share Posted October 21, 2022 On 17/10/2022 at 20:54, SteamyTea said: EDF are going to charge me 34p/kWh for night usage. How come? Is that not the capped price for daytime? Night rate should be lower. If that is the best you can get then E7 / E10 is dead, switch to single rate and ditch the storage heaters. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 21, 2022 Share Posted October 21, 2022 25 minutes ago, ProDave said: How come? Is that not the capped price for daytime? Night rate should be lower. If that is the best you can get then E7 / E10 is dead, switch to single rate and ditch the storage heaters. Yes. I think the reason is, to hit an annual mean price of 2500, they use the E7 mean usage of 4.2 MWh/year. About a third of everyone else's. Small one bed flats maybe, not a normal house. Link to comment Share on other sites More sharing options...
billt Posted October 21, 2022 Share Posted October 21, 2022 Don't understand. Our 7 hour rate has reduced in price, now 17p per unit, day time rate 44p per unit. The rates don't vary depending on the size of the property. Link to comment Share on other sites More sharing options...
JackofAll Posted October 21, 2022 Author Share Posted October 21, 2022 4 hours ago, TerryE said: If you use a warm slab (See MBC website profiles), though other specialist builders do these as well, then your main thermal store is the slab itself. Willis-only isn't cost effective for new build with current electricity prices. Better to go for energy efficient build and ASHP direct into slab circulating UFH water at ~35°C so CoP should be around 4. A few there have done this very effectively. The issue you will have is getting an MCSE installer to do this for you because their standard templates don't work for such energy efficient builds. However you don't actually need to use an MSCE installer as this can be signed off by your Binsp, esp is you have a private one. You just need to do all of the calcs to prove conformance to BRegs Plan is a Kore slab, as Jamie said earlier the initial capital outlay was putting me off and most trades over here think every customer has a saddle on their back, what Iceverge said. What's an MSCE? Link to comment Share on other sites More sharing options...
JackofAll Posted October 21, 2022 Author Share Posted October 21, 2022 (edited) As it so happens I contacted BPC for a quote for MHRV system and they sent the attached quote for A2W as well not sure why, maybe just chancing their arm but it wasn't as expensive as I'd initially thought, though the cylinder is mad money. So It can be plugged in direct to UF Terry? Edited October 21, 2022 by JackofAll Link to comment Share on other sites More sharing options...
Nick Thomas Posted October 21, 2022 Share Posted October 21, 2022 (The actual rates EDF are charging E7 customers: https://www.edfenergy.com/sites/default/files/government_energy_price_guarantee_prices._standard_variable_deemed_and_welcome._credit_meters.pdf ) 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted October 21, 2022 Share Posted October 21, 2022 38 minutes ago, Nick Thomas said: (The actual rates EDF are charging E7 customers: https://www.edfenergy.com/sites/default/files/government_energy_price_guarantee_prices._standard_variable_deemed_and_welcome._credit_meters.pdf ) That's interesting, this is the price list I got sent. Link to comment Share on other sites More sharing options...
Nick Thomas Posted October 21, 2022 Share Posted October 21, 2022 Yes. Read the section in bold: "All prices are the Ofgem Default Tariff Cap rates before discounts under the Government Energy Price Guarantee have been applied". Once those discounts are applied - and they will be applied - you get the rates in the PDF I linked. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 21, 2022 Share Posted October 21, 2022 30 minutes ago, Nick Thomas said: you get the rates in the PDF I linked. I hope so. I think I get a bill fairly soon. As I am only using 3 kWh/day at the moment, and am still on target to use 3 MWh/year this year (did not start cutting back till May), the yearly bill will not be drastic, especially as I am getting £550 off in total. Just for the record, [22:27 21/10/2022] my house is at 21°C and outside is at 13°C. Been a dull, rainy day. Link to comment Share on other sites More sharing options...
TerryE Posted October 22, 2022 Share Posted October 22, 2022 (edited) 14 hours ago, JackofAll said: What's an MSCE? Most commonly Microsoft Certified Solutions Expert but in this case a Microgeneration Certification Scheme certified engineer. The installation must comply with MICROGENERATION INSTALLATION STANDARD: MCS 020. In essence this determines the maximum noise level at the neighbours boundary. This is normally achieved by using a certified engineer to sign off the installation. The Planning Portal states that planning permission is not required if ASHP "equipment must be installed by an installer who has been certificated through the scheme using a certificated product" -- that is self-certification is not permitted. It also lays down other limitations. All other cases must be covered though a planning application, but whether your BInsp will allow self-certification is another matter. Edited October 22, 2022 by TerryE Link to comment Share on other sites More sharing options...
JackofAll Posted October 23, 2022 Author Share Posted October 23, 2022 On 21/10/2022 at 15:55, Iceverge said: There's some new Mitsubishi ASHPs on donedeal at the moment for €1700. If you DIY install you're looking at less than a 2 year payback. Plumbers in Ireland are taking the proverbial with their prices. It was €7-10k extra for an ASHP for us plus fitting. I couldn't stomach the gouging. If you're any way handy the Hep2O plumbing system is childsplay. Even on our passive house payback would be less than 3 years. Not the 25+ it would have taken had we paid the plumbers. Had a look, didn't see new ones but 2 secondhand ones. Link to comment Share on other sites More sharing options...
JackofAll Posted October 23, 2022 Author Share Posted October 23, 2022 On 22/10/2022 at 10:16, TerryE said: Most commonly Microsoft Certified Solutions Expert but in this case a Microgeneration Certification Scheme certified engineer. The installation must comply with MICROGENERATION INSTALLATION STANDARD: MCS 020. In essence this determines the maximum noise level at the neighbours boundary. This is normally achieved by using a certified engineer to sign off the installation. The Planning Portal states that planning permission is not required if ASHP "equipment must be installed by an installer who has been certificated through the scheme using a certificated product" -- that is self-certification is not permitted. It also lays down other limitations. All other cases must be covered though a planning application, but whether your BInsp will allow self-certification is another matter. Thanks Terry, not sure if that's applicable this side of the pond, am open to correction though. Link to comment Share on other sites More sharing options...
Iceverge Posted October 23, 2022 Share Posted October 23, 2022 https://www.donedeal.ie/tools-for-sale/mitsubishi-air-to-water-heat-pumps-puhz-w50vha-bs/31698623 Link to comment Share on other sites More sharing options...
Ferdinand Posted October 23, 2022 Share Posted October 23, 2022 Someone's gonna be busy ... 😁 Link to comment Share on other sites More sharing options...
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