Go to Forum Home Building Design Greetings from aspiring ecobuilder – PV query

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    • #30682

        Greetings from a brand-new member. I was referred to this website by the glowing recommendation from Bob Matthews in his article in the latest 'SelfBuild & Design' magazine, and I have been watching the posts for the last few days. I see that I have a lot to learn, but I hope that you well-informed and experienced people will be kind enough to offer advice.
        We are about to begin a huge (for us) ecoproject, and I will have many questions to ask the appropriate forums here!

        First question – can you suggest a PV rooftiling product which has a plain matt slate effect surface? Wierd, but the Planner says we can have an entire PV roof if it causes no dazzle or glare. Website and brochure photos do not provide enough information on dazzle factor!

      • #33878
        Mark Siddall

          I presume that you are building a Gold standard house before seeking to apply PVs to the roof. (The Gold standard is considered to be the cheapest way of achieving a low carbon building. Cost per pWh saved PVs remain very expensive.)
          As for PVs I have not heard of matt glass being used on PV. I might be being pedantic but here are some low reflectance glass products on the market though I'm not sure whether the PV manufactures have icked upon them at this point.


        • #33879

          My own house (under construction – shell complete) has some large PV glass laminates in the south roof (all the south roof is glass) and I can't say that I've ever seen any reflections when standing on the ground.

          The strip near the ridge, and the north roof, are Welsh slate. They don't look the same but they do blend in; the colour of solar single crystal cells is similar to Welsh blue slate.

          Talking of which, single crystal cells are much more matt than polycrystalline so I'd go for them. I totally concur with Mark's advice about priorities – PV doesn't make economic sense until you've done almost all else to savce CO2, such as installing the world's most energy-efficient refrigerator or freezer.


        • #33880

            Thank you for your kind replies. If you could recommend particular products for me to investigate, that would be very helpful.

            I believe the Planner may have been influenced by early examples of PV cells, which were definitely silvery-backed when I first saw them at Machynlleth 20? years ago.

            Please rest assured that we are aspiring to a 'Gold standard' new build (although I have developed an aversion to low-energy lightbulbs!). We both trained as architects, and this is our first project entirely for us, allowing for the Planner's opinions, strategically.

            This will be a five-bed contemporary house in rural Herefordshire, mostly located underground. The site borders a flood plain, and is exposed to the '1000 year flood.' The house replaces a pair of tiny nasty cottages, and so above ground the Planner insisted on a very small built volume. Consequently, we have just achieved Detailed Planning Permission for a boat-like house we call the 'Arkalow'.

            The basement zone is an ingenious agricultural prefab concrete tank system, usually used for water, silage or sewage! Into this we 'drop' a green oak hybrid frame, with SIPS panels for the outer walls around a vast open plan space. A South facing catslide roof offers the PV possibility, with Redland Cambrian reconstituted slates to the North roof. The two upper storeys display the oak inner structure. UF heating, powered by geothermal sources, or even by the PVs if we can get enough area. So, many questions and months of detailing ahead!

            My PV starter query is due to Planner suggesting delegated powers for minor alterations, so the search is on for the matt PV product! If we can find one to please him, it may calculate to offset the need for geothermal pipes/terrathermal borehole, and so prove cost effective.

            Whilst it seems illogical to consider the roof surface first, it has major implications for the amount (and cost) of groundworks in the next few weeks!

          • #33881
            Nick Grant

              Hi Julia

              Reading between the lines I think you have your work cut out! You mention a few things that will, I am sure, spark critical responses so I'll just mention lighting!!

              You have to go low energy! I agree badly done low energy lights are horrid but anything less than best practice would make a mockery of PV.

              I have plugged my friend Colin Chetwood elsewhere (and his website shows up in Google). As an artist he was a low energy light sceptic but we have collaborated.

              David, any chance of some pics of your house, needn't give away any clever details.

              Herefordshire AECB Mafia

            • #33882
              Nick Grant

                Glad you like Colin's lights.

                High frequency T5 tubes operate way above the flicker level and with right ballasts can be dimmed.

                CFLs take a while to warm up and as the light is more diffused they can seem less bright than equivalent GLS.

                Smaller CFLs fit in task lights fine. I have a collection of classic angle poise lamps prom car boot sales etc.

                Re cost, even the most expensive gold plated low energy luminaires will still be cheaper per kWh saved than PV.

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