Solar glass: Aesthetics and returns on investment

Building integrated solar photovoltaics (BIPV) solar electric glazing is being increasingly used by architects and builders here as an innovative and green energy solution.

Generating electricity

Glass has come a long way from a building product that only provided a view and kept out the weather. Glass and glazing products are now available as active elements that contribute to a building's energy and environmental concerns. BIPV electric glazing works by adopting a technology called Photovoltaic (PV). A semiconductor silently converts sunlight into electricity with no moving parts, no depletion of resources, no waste or emission and no fuel is required beyond free sunlight falling on it. Driven by innovative architects and designers, supportive markets and aggressive programmes in Europe, US and Japan over the past 10 years, the BIPV solar glazing technology is now beginning to find a place in India.

The technology

BIPV is building integrated photovoltaics, a technology for integration of energy needs of buildings with the building architecture and solar photovoltaic technology. BIPV electric glazing generates electricity from the sun. It reduces thermal radiation in to buildings and allows natural daylight to pass through. They replace conventional construction materials like glass/granite/marble etc. BIPV solar electric glazing looks beautiful and enhances the building's aesthetics. In short, BIPV solar electric glazing is used as architectural elements such as roofing, skylights, rain screens, or curtain walls. Using them as integral part of the building saves costs associated with conventional materials like glass, marble, granite or concrete. Energy generated by solar electric glazing can be stored and used for meeting the building's energy needs. Hence, it could serve as an alternate energy generator.

Products

Three typical products are available to suit varying needs and budgets. Units ranging from six to 1.5 watts per square metre are available in the market today. Level of glass transparency could be varied through control of spacing between the solar cells. Standard products offer light transmissivity at 23 percent towards buildings' insides. Two colours - bluish and grayish solar cells are available. Typical power output from BIPV solar electric glazing is 100 watts per square metre under standard test conditions. Single panels of 350 watts power and 40 sqft size are available. A single glass product offers transparent BIPV glazing and is recommended for atriums and canopies. Double glass products offer sandwich panel between BIPV glass and a back glass with a resin layer in between. This product will cut UV rays (protecting the interiors) and assist to improve sound and heat insulation of the building. They find applications in roofs, facades, and atriums.
Triple glass products incorporate a double glass product in the front and a back glass separated by a spacer with sealing all round. This offers excellent sound and heat insulation properties and reduces air condition loads significantly. Many projects have been implemented in Bangalore, Delhi and Kanpur for individual, corporate and government buildings. Applications include curtain wall, rain screen cladding, and roofing.

The payback

Every building has some portion of its design and construction budget allocated to make it special - to define and create a unique character or make a 'statement' on behalf of the client. In corporate and institutional architecture, this has often been accomplished using premium building materials. Solar electric skin offers a cash flow stream for 20 plus years to come. In summary, solar electric glazing is a highly innovative and clean product, offering purpose statement and value for money to the investor. It holds significant potential towards making our future generation green.