Lightweight ‘solar cloth’ photovoltaics have flexible future

A Cambridge start-up believes its flexible solar panelling solution could fundamentally change the landscape of solar installation in the commercial sector.

The Solar Cloth Company’s award winning flexible thin film photovoltaics (FTFP) are a few micrometres thick and can be integrated into flexible and lightweight tensile structures called building integrated photovoltaics (BIPV). In doing so, they provide an alternative to traditional photovoltaic panels that are heavy and cumbersome.

The Solar Cloth Company’s Perry Carroll, CEO and founder, and Christopher Jackson, innovation director told The Engineer via email that copper indium gallium diselenide (CIGS) is used as a base technology because it is known for its higher light-to-electricity conversion rate and lightweight flexible properties. The technology is also 100 times thinner than conventional silicon (c-Si) glass backed solar panels.

Carroll said: ‘At the moment there is a lot of interest in carports and commercial roofing. Most steel portal commercial roofing cannot support the weight of heavy glass solar panels, but our lightweight solar cloth is ideal in these situations.

‘We estimate there is around 830 million square meters of commercial roof space and 350 million square meters of car parking space in the UK alone which, if covered with solar panels, could produce enough power to feed the UK’s national grid three times over.’

The duo added that CIGS is favoured because it is suited to northern latitudes such as the UK.

Jackson said: ‘To put this in numbers, the spectrum absorbed by silicon cells ranges from 400-700 nm, while the absorption range for CIGS cells is wider from 300-1300 nm. This means that the effective time for generating power is much longer each day for CIGS than other technologies.

‘There is also the lifetime degradation issue of silicon. Both crystalline silicon and amorphous silicon PV exhibit degradation following long-term exposure to strong light, which reduces their ability to generate electricity.

‘And finally, in terms of sustainability, because CIGS uses a 100 times less semiconducting material than silicon cells, the embedded energy used to manufacture them is less. According to the US Department of Energy, assuming a 30 year-life of the solar installation, crystalline silicon PV payback time is estimated to be 2-4 years. CIGS PV payback time is estimated to be 1-2 years.’

The company has already unveiled the world’s first solar fabric tensile structure car park in Cambridge and has been awarded BIPV innovation of the year at the UK Solar Industry awards. Similarly, RBS has awarded the technology winning status in their search for the next big innovation in sustainability.

Carroll said: ‘They will be testing our product in new carbon neutral branches throughout their estate of 2,500 buildings, We are also very excited to be in discussion with two well-known London museums who have set us the challenge of solarising their buildings in ways that complement their period design.’

Jackson added: ‘We are currently closing in on deals involving 27,000 car park spaces with leading UK retailers and 15 Local Authorities.  We have built a growing sales pipeline worth £4.2 million for 2015 including park and ride projects, airport parking operators and retail park owners.

‘Further, we are trailing new-to-market flexible, lightweight building integrated solar installations with one of the UK’s biggest retailers in January 2015.’

The company is looking for investors and has turned to crowd funding mechanism Crowdcube to raise £750,000 in return for a 10 per cent equity stake.

Carroll said: ‘This investment will enable us to scale up the human resources of the company in terms of sales and marketing and administration. This will mean we can fulfil our growing pipeline of orders quicker and deal with the growing global interest in our products.’