Building integrated photovoltaic systemsIt is expected that by 2015, global BIPV market will reach 1.6 GW, especially in the European markets.
What’s happening right now?
Photovoltaics presently conjure up the image in our minds of flat panel solar cells, fitted typically on flat roof tops, slanted at an angle towards the sun to harvest solar power. Almost all of these flat panel solar cells were added to pre-existing buildings and consequently had limitations to their installation and use. Since the 1990s, the architects and builders have spawned the new practice of integrating solar photovoltaics into a building at the conceptual stage, for the so-termed Building Integrated Photovoltaics ( BIPV). With BIPV, the building does not suffer from the limitations of an add-on afterthought and also results in reduced cost. And with the trend towards “green buildings”, the BIPV market is projected to reach $ 8.2 billion by 2015. These photovoltaics will also produce 1.6GW of clean power. Supporting this growth the industry is a whole slew of new products that will give architects and building designers more options to design greener buildings without any compromise on form, aesthetics or function of the buildings.
1. Uni-Solar laminates by United Solar Ovonic LLC:
UNI-SOLAR laminates by United Solar Ovonic LLCUnisolar thin film amorphous PV Solar Laminates are flexible solar modules that are bonded directly to the roof.
The pictures above shows Uni-Solar flexible solar modules being directly bonded to the roof of a General Motors factory building in comparison with the conventional roof top panels. The advantage immediately obvious is that the photovoltaic area available for harvesting the solar energy is much larger with the laminate than with the crystalline silicon cells behind glass panels. The flexible modules do not need the additional steel support brackets that add to cost and also to the loading of the roof. The flexible modules weigh only 1lb per sq.foot. Uni-Solar also claims that their modules are designed to absorb solar energy not just from the visible spectrum of sunlight but also from its infra-red and ultra-violet spectra increasing the energy harvested by some 20% per sq. foot of module.
2. Power FLEX BIPV panels:
PowerFLEX BIPVPowerFLEX BIPV by Global Solar.
Global Solar of Tucson, Arizona is another company that offers flexible solar modules that can be directly bonded to the roof of a building. Global claims that its thin film CIGS (Copper Indium Gallium diSelenide) modules are the highest in energy efficiency at some 13.2% where they approach the efficiency achieved with crystalline silicon solar cells. They offer these flexible modules in strips upto 19 feet length and 1.5 feet width that permit these modules to be installed on any shape or contour of surface. They claim that the installed cost of these modules is the same as crystalline rigid cells.
3. Dow’s Solar shingles:
BIPV system Dow Solar SolutionsBIPV system Dow Solar Solutions cost about 40% less than other solar panels.
Dow Solar Solutions, a division of the giant Dow Chemicals has launched a new range of products that can be installed like conventional roof shingles, maintaining the appearance and heritage features of buildings. These can be installed like regular roofing tiles and are said to cost some 40% less than competing products. They are also said to be 10% more efficient than crystalline solar panels while costing 15% less for equivalent power capacity.
4. Konarka Technologies “Power Plastic” flexible transparent solar panels:
konarka power plastic organic photovoltaic materPower Plastic is lightweight, thin, flexible, portable, and beautiful.
In any tall office or commercial building, the vertical faces are always much larger than the rooftop and if the vertical faces can be used to harvest solar energy, the benefits would be much larger than using only the rooftops. Konarka Technologies, a Lowell, Massachussets company, founded by Dr Alan Heeger, the Nobel Prize winner for Chemistry in 2000 for his work on conductive polymers, has introduced its family of Organic Photovoltaic panels that is semi-transparent and comes in various colours. This enables the solar film to be applied to vertical facades of buildings, dramatically increasing the surface area for harvesting solar energy. Konarka also claims that its solar film generates electricity for longer hours each day, from near sunrise to sunset, by being able to absorb energy from the whole sunlight spectrum. They also claim that their film can absorb indirect or reflected light and can even respond to interior lighting of the building on which it is installed.
Konarka claims an efficiency of 8.3% in lab test conditions which is a major advance over its own previous organic photovoltaic film which had efficiencies in the 2-3% range. Konarka has also tied up with a windows manufacturing company to manufacture windows and curtain walls with the Power Plastic film bonded with the glass. It has also converted seven large windows at its own headquarters building to demonstrate this application.
These new technologies, as they grow and develop, will speed the process of adoption of Building Integrated Photovoltaics into the design of new buildings and into the refurbishment of older buildings that would be an important step towards a greener building industry.
At this early stage of development of these technologies, the questions of cost are still left deliberately vague. The crystalline silicon modules presently used the cost around $11,000 per kW which is adopted only with government subsidies both for capital cost and for assured buying of the power generated at rates better than utility power. While such subsidies are acceptable at the early stages of adoption of new technologies, the industry needs to rapidly get the costs down to the level of the present fossil fuel based power generation .
The second major concern is that of life of these new photovoltaics. With thin flexible films being the common thread between these different technologies, the question in many people’s minds is whether these will have the same lifetime, which is at least 25 years, for other materials used in the buildings industry. If the life is likely to be less, whether these systems can be replaced or re-furbished without shutting down the building for long period of time.
The Building Integrated Photovoltaic industry appears to be coming of age with a new range of technology options and products that permit the photovoltaics to be built into the design of the building. With improvements to cost and life, hopefully, photovoltaics would come to be as commonplace as the use of glass or steel in the building industry.