heating, ventilation & services
Integrating solar PV into building design
Experts at BRE examine how solar PV can provide an affordable way to meet the energy requirements of Building Regulations and the Code for Sustainable Homes. They look at the impact that the feed-in tariff scheme has had on the UK market, opportunities for building-integrated approaches and highlight the soon to be opened BRE National Solar Centre
of solar technology in the UK and also an increase in the number of installations. Installed capacity for systems under 5 MW (5 MW is equiv-
T
alent to a 25-acre field) has increased dramatically from around 26 MW at the start of 2010 to over 1.3 GW at the end of September 2012 (Ref: Ofgem FIT Installation Report 30 Sept 2012) – a 50-fold increase in installed capacity. This large increase has seen a number of impacts including a number of ‘solar PV gold rushes’ to beat changes in the tariff level, but also significant reductions in the capital cost of solar PV. In 2007 prices were around £6,000–£8,000/kW installed; today prices vary from £1,800 to £2,500/kW installed, depending on the scale of the project. A typical semi-detached house has roof space for 2 kW, so in this case installed costs have fallen from £14,000 to £5,000 for a solar PV system. Because of these price reductions, the investment return is still good in percentage terms; equally importantly, consumers are also protected against the full impact of future rises in electricity costs. Consumers and specifiers should be wary of a lowest-cost approach to solar PV, and should also retain a focus on the quality of the products and installers used. As the price of PV has reduced by a factor of approximately
four, it is becoming seen as a cost-effective way of meeting the carbon reduction targets for newbuild homes set out in the Code for Sustainable Homes, specifically credit Ene 1 Dwelling Emission Rate. While this does not negate the need to build warm, energy-efficient homes, the use of solar PV can reduce net CO2
emissions. Additionally, as government officials such
as those in DCLG responsible for the Building Regulations realise the benefits of solar PV, it is a possibility that future revisions will reflect these changes in the market. There are also a number of other interesting issues arising
at present. One such issue is the development of many new building-integrated PV (BIPV) products where the PV can form an integral part of cladding or roofing systems leading to potential aesthetic improvements (currently BRE has over 90
he government’s feed-in tariff (FIT) scheme, intro- duced in April 2010, has had a number of significant impacts, notably a large reduction in the capital cost
products on file); this is an area of active research. While his- torically perceived to be a luxury product with limited applica- tions, the latest products are reliable, allow design flexibility and are multi-functional (eg providing thermal insulation).
‘PV can form an integral part of cladding or roofing systems leading to potential aesthetic improvements’
Photo: Nu-Lok Integrated solar PV
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Another interesting area is the emergence of domestic-scale
energy storage units (usually batteries) with capacity for a few hours’ worth of electricity under normal usage patterns. This can extend the benefits of solar PV beyond daylight hours. The first cost-effective products are starting to appear on the market and will become more important with the emergence of smart grids. Meanwhile BRE has been developing a BRE National Solar
Centre (NSC), which will open in April 2013 and will support the UK solar industry to grow, mature and thrive to become up to a 22 GW market by 2020. The now stable rates for the FIT and the solar RO (renewables obligation for larger projects) give the industry the platform required to make this happen through domestic, non-domestic, commercial roofs and ground-mounted solar parks. The NSC, which is a £1.1 million project, 75 per cent funded by Europe, will provide evidence-based information on design and installation tech- niques, performance, durability and costs to the solar industry,
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