Meabh Posted April 12, 2023 Share Posted April 12, 2023 Our old house is now demolished and groundworks start on the new build at the end of the month so we are now making lots of decisions and need some help. - We need 4kW of PV to pass our SAP (using a gas boiler with UFH & MVHR. Heat pump ready but ££ didn't work out for it). - Location - near Edinburgh - The roof is south facing, 12 degrees pitch (so can't do in roof) standing seam metal. Plenty of room for solar & it's on planning. - Plan is to divert any excess solar to an immersion and HW tank (as we don't have an electric car and not getting a battery yet) - Family of 2 adults & 3 kids ages 6-11, work from home. Any thoughts on the quotes below - sizes/price/products/advice? Thanks Solar PV 1 4.05kw - 12 x 405w DMEG Solar Panels 3.6kw - 1 x Solis Inverter On-Roof Standing Seam Mounting System Fully Installed Price of £5919.55 Solar PV 2 7.29kw - 18 x 405w DMEG Solar Panels 6kw - 1 x Solis Inverter On-Roof Standing Seam Mounting System Fully Installed Price of £7375.55 Link to comment Share on other sites More sharing options...
Conor Posted April 12, 2023 Share Posted April 12, 2023 How much insulation / glazing spec are you planning? I'm surprised you need that much PV. Second option is much better value, but you'll need a three phase supply and G99 approval from the DNO. We've 4.5pKW, cost £5k. Wish we could have got more. Link to comment Share on other sites More sharing options...
JohnMo Posted April 12, 2023 Share Posted April 12, 2023 If you need 4kW PV to pass your SAP, you really need to take a look at the insulation you are putting in, it must less than than the bare minimum. 1 Link to comment Share on other sites More sharing options...
Seren161 Posted April 12, 2023 Share Posted April 12, 2023 Considerably cheaper than what we paid.. i The Solis inverter is Chinese and not as expensive as the German ones but by what I heard from an installer ..works perfectly fine. Seems reasonably priced ..I’d get the 7.29kWp array if finances allow. I thought DNO approval was over 10kWp? 3 phase electricity is usually expensive so worth really considering this. We were only 5.5kWp but in (sunny) Dover with a hybrid Fronius inverter ( to keep the battery option open) and 3 phase electric ..was considerably more expensive.. and still wish we went for a larger array … 1 Link to comment Share on other sites More sharing options...
JamesPa Posted April 12, 2023 Share Posted April 12, 2023 (edited) 23 minutes ago, Meabh said: Our old house is now demolished and groundworks start on the new build at the end of the month so we are now making lots of decisions and need some help. - We need 4kW of PV to pass our SAP (using a gas boiler with UFH & MVHR. Heat pump ready but ££ didn't work out for it). - Location - near Edinburgh - The roof is south facing, 12 degrees pitch (so can't do in roof) standing seam metal. Plenty of room for solar & it's on planning. - Plan is to divert any excess solar to an immersion and HW tank (as we don't have an electric car and not getting a battery yet) - Family of 2 adults & 3 kids ages 6-11, work from home. Any thoughts on the quotes below - sizes/price/products/advice? Thanks Solar PV 1 4.05kw - 12 x 405w DMEG Solar Panels 3.6kw - 1 x Solis Inverter On-Roof Standing Seam Mounting System Fully Installed Price of £5919.55 Solar PV 2 7.29kw - 18 x 405w DMEG Solar Panels 6kw - 1 x Solis Inverter On-Roof Standing Seam Mounting System Fully Installed Price of £7375.55 I put 4kW in 12 years ago and am now trying to upgrade which is proving difficult. Wish I'd put more in from the start. Electric vehicles, ashp and better export prices are here or on their way and these only increase the attraction. Furthermore overdimensioning means you still get meaningful output in the shoulder season. I'm not sure how the maths works cost wise, but it's a long term investment and electricity is the way to go. Edited April 12, 2023 by JamesPa 1 Link to comment Share on other sites More sharing options...
Meabh Posted April 12, 2023 Author Share Posted April 12, 2023 33 minutes ago, Conor said: How much insulation / glazing spec are you planning? I'm surprised you need that much PV. Second option is much better value, but you'll need a three phase supply and G99 approval from the DNO. We've 4.5pKW, cost £5k. Wish we could have got more. We are 0.14W/m2k for walls, triple glazing...we are coming out as a 91/92 so A/B. I think i'm using the word "pass" wrongly - when I asked the architect why we needed that particular amount of PV they said it was a plug to "Pass" the SAP. I know about DNO approval - but do there has been no mention about 3 phase? 30 minutes ago, JohnMo said: If you need 4kW PV to pass your SAP, you really need to take a look at the insulation you are putting in, it must less than than the bare minimum. We are 0.14W/m2k for walls, triple glazing...we are coming out as a 91/92 so A/B. I think I'm using the word "pass" wrongly - when I asked the architect why we needed that particular amount of PV they said it was a plug to "Pass" the SAP Link to comment Share on other sites More sharing options...
joth Posted April 12, 2023 Share Posted April 12, 2023 1 hour ago, Meabh said: On-Roof Standing Seam Mounting System Why are you doing on-roof on a new build? You'll save the cost of a lot of tiles, and a bunch of maintenance headaches, by going in-roof rather than on roof. 40 minutes ago, Meabh said: We are 0.14W/m2k for walls, triple glazing.. Do you have a number for total heat demand kWh/m2/year ? Walls and window U value alone only tell a fraction of the story. Floor, roof, quantity of glazing, and airtightness level all play just as big a part. 1 Link to comment Share on other sites More sharing options...
Dillsue Posted April 12, 2023 Share Posted April 12, 2023 1 hour ago, Meabh said: I know about DNO approval - but do there has been no mention about 3 phase? Not sure why you'd need 3 phase?? We've got 2x3.68kw(7.3kw) inverters on a single phase connection so your 6kw could be doable on a single phase. Link to comment Share on other sites More sharing options...
Meabh Posted April 13, 2023 Author Share Posted April 13, 2023 12 hours ago, joth said: Why are you doing on-roof on a new build? You'll save the cost of a lot of tiles, and a bunch of maintenance headaches, by going in-roof rather than on roof. Do you have a number for total heat demand kWh/m2/year ? Walls and window U value alone only tell a fraction of the story. Floor, roof, quantity of glazing, and airtightness level all play just as big a part. Roof is only 12 degrees so installer has said not suitable for in roof? From the SAP Heating 13,841 kWh/year so 45kWh/m2/yr Water 2,392 kWh/year so 8kWh/m2/yr So total heat demand 53kWh/m2/year - these will be from a gas boiler, everything else in the house is electric. Link to comment Share on other sites More sharing options...
mattman Posted April 13, 2023 Share Posted April 13, 2023 (edited) I'd go for the second option. You don't need three phase for that size. Your installer should do the DNO G99 application for you, or you can do yourself. I did ours and only took half an hour or so (although I did do a lot of reading on the subject before hand as well as getting a schematic design from the inverter manufacturer). We are single phase, and have a steel standing seam roof with 7.6kW PV array (19 panels) already installed but waiting for our G99 to come back for our inverter and battery storage. Personally I would get battery storage too if you can as you avoid paying VAT on them plus you have the option of storing excess energy instead of it going back to grid for very little whereas you can use stored energy in the evenings to run appliances in your home or if you have a powercut. The Solis 6kW is a good inverter as it is capable of running continuous loads in your home up to 5kW (when running off batteries such as in evening or in a power cut) or 6kW loads when connected to the grid. The smaller 3.68 kW solis inverter will only handle much smaller loads up to 3.6kW so not worth it in my opinion compared to the larger 6kW inverter. Hope it all goes well. Edited April 13, 2023 by mattman 1 Link to comment Share on other sites More sharing options...
Simon R Posted April 14, 2023 Share Posted April 14, 2023 I'm for option 1 and spend the difference on battery storage. Our place is ICF and we use a small combi gas boiler for hot water, no HW storage. We don't have UFH either, and rely on a 3.5kW A2A unit in the open plan living area to provide heating and cooling as required. Using an A2A split unit was a lot simpler and cheaper than going for an ASHP and UFH. Even at this time of year we are getting enough power to run the house with very minimal import, 0.39Kw yesterday and 7.7kW export. Our battery is 9.5kWh. I've got and EV but only charge it from the Octopus Intelligent tariff overnight, trying to charge it from the solar during the day was more complex than initially envisaged. Hopefully I'll get it sorted soon so I'm no longer exporting. Link to comment Share on other sites More sharing options...
Meabh Posted May 24, 2023 Author Share Posted May 24, 2023 Hi All So we've had the quote updated given the feedback above. We will also be getting an ASHP (7-8kw) and have UFH downstairs & MVHR and everything else will be electric. We are in Scotland so the HES grant will reduce the PV/Battery quote below by another £2.5k making it £10.5k for the below fully installed. We are a family of 2 adults (work from home) and 3 primary school kids. Roof is SOuth facing but 12 degrees pitch and unshaded - East coast near Edinburgh. Does this seem sensible? Many thanks Solar PV with Battery Storage 7.29kw - 18 x 405w DMEG Solar Panels 6kw - 1 x Solis Hybrid Inverter 10kWh Battery Storage - 2 x 5kWh PureDrive Batteries On-Roof Standing Seam Mounting System (assumed use of onsite scaffold will be available) Link to comment Share on other sites More sharing options...
SteamyTea Posted May 24, 2023 Share Posted May 24, 2023 2 minutes ago, Meabh said: Roof is SOuth facing but 12 degrees pitch and unshaded - East coast near Edinburgh. Have you run your angles through PVGIS. Link to comment Share on other sites More sharing options...
Meabh Posted May 24, 2023 Author Share Posted May 24, 2023 2 hours ago, SteamyTea said: Have you run your angles through PVGIS. Yes - not great in Dec/Jan - anything in particular I should be looking for? Link to comment Share on other sites More sharing options...
SteamyTea Posted May 24, 2023 Share Posted May 24, 2023 35 minutes ago, Meabh said: Yes - not great in Dec/Jan - anything in particular I should be looking for? Not really. Link to comment Share on other sites More sharing options...
Dave Jones Posted May 24, 2023 Share Posted May 24, 2023 get the in roof modules soo much cleaner. Link to comment Share on other sites More sharing options...
Meabh Posted May 24, 2023 Author Share Posted May 24, 2023 2 hours ago, Dave Jones said: get the in roof modules soo much cleaner. Roof pitch is too low at 12 degrees and it's standing seam Link to comment Share on other sites More sharing options...
Dave Jones Posted May 24, 2023 Share Posted May 24, 2023 increase the pitch, will look miles better than a bunch of scaffold holding panels on. Link to comment Share on other sites More sharing options...
SteamyTea Posted May 24, 2023 Share Posted May 24, 2023 3 hours ago, Dave Jones said: increase the pitch, will look miles better than a bunch of scaffold holding panels on. I think you can get modules that fit within the seams. They clamp to the upstands. Link to comment Share on other sites More sharing options...
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