Housing Sustainability Matters Number 2 - Here Comes The Sun

• The solar input to the earth is 10,000 times the energy the world currently uses from coal, oil, gas and nuclear power put together.
  
• We can generate clean electricity from the sun, without the side effects of pollution and the other social and environmental impacts that a dependence on non-renewables gives us.
  
• The technology for generating electricity from the sun (solar photovoltaics, or PV) is fast improving in efficiency, works well in the UK climate and the costs are tumbling down.
  
• Another way of using the power of the sun, easier to do and very cost effective, is called solar thermal, in which the sun's energy is used to heat water, reducing a typical gas bill by 40%.
  
• Lambeth Housing is currently involved in its fourth solar PV project and many solar thermal projects.

Why?

• Solar energy is pollution free.
• Localised production of electricity help to reduce energy insecurity in an era when electricity prices and availability are becoming increasingly uncertain.
• The UK government has set a target of 10% energy production from renewable sources by 2010.
• A solar PV tiled roof could prevent over 34 tonnes of greenhouse gas emissions during its lifetime.
• An opportunity for Lambeth Housing to demonstrate its commitment to combating climate change and engaging with people's concern about environmental issues.

Simply put, two options - PV and thermal

• Solar PV is the more expensive of the two. But once installed, it generates free, clean electricity.
• Solar thermal is cheap and pays back quickly. It supplements the hot water in a boiler.

Costs and benefits

PV will deliver electricity to a building which can be used directly in the building services, with any excess being exported to the grid and a price received for this. Solar PV cells will rarely need replacing during the lifetime of the building. PV cladding, which can look very attractive, costs as little as £500 per square metre. The payback period for PV obviously varies according to the building. At present, PV is a long term investment for Lambeth Housing, but one which is likely to pay many fold when the effects of climate change and fuel insecurity are accounted for.

Solar thermal panels supplement the hot water supply for a building, typically reducing gas demands for the boiler by 40%. Even on a cloudy day, these panels will raise the temperature of the water such that much less gas is needed to heat the water. Payback is likely to fall well within 10 years, with the cost of a panel for a typical domestic property currently between £2,500 and £4,000.

Can I do it?

Yes. Well, probably. Both systems work best on south facing or southwest facing pitched roofs of any building type. If you have a flat roof, and can't change to pitched, then why not consider a green roof?

Funding

• 50% funding for PV is available from the Energy Saving Trust. Contact the Environment team on 020 7926 3510 to discuss any ideas.
• Substantial grant funding is also available for solar thermal from Solar for London. Again, contact the Environment team to discuss projects or ideas.

Solar PV Lambeth

South Bank Youth Resource Centre, SE1
2kWp PV array; Tomkyns House, SE11
3.3 kWp PV array, plus solar thermal; Langholm Close, SW2
21kWp PV integrated solar tiles on sheltered housing; Boatemah Walk, SW9
14.5kWp PV roof, fully integrated AluPlus Solar standing steam roof.

Web resources

www.solarforlondon.com
www.solarcentury.co.uk
www.est.org.uk/myhome/generating/how