Building Integrated Photovoltaics (BIPV)
Good products should not only satisfy the end-user’s needs, but also be advantageous to the environment, where the product will be used. Electricity is no exception to this rule. Solar electricity can make a contribution to world energy supplies, while simultaneously helping us slow down global climate change.
Approximately 75% of the energy used in developed world is consumed in cities and up to 40% of that energy is used in buildings. Tomorrow’s buildings should not be used just for housing. Homes and offices have traditionally had very little built-in intelligence. However, new advanced systems and devices are increasingly being added. Along with emerging environmental awareness, the construction of energy efficient buildings is achieving greater popularity. A general agreement is arising that tighter controls are needed on the effects on our environment and that people should use more energy efficient systems.
The electrical demand of a large office building usually exceeds the production of a solar power system installed on it, meaning that all solar electricity produced can be used within the building. In this way, the solar power system reduces the building’s external energy demand. Commercial buildings are a very attractive application for photovoltaics. Solar modules lend themselves to many uses, where they can replace more expensive building surfaces – and even offer additional benefits. For example, in facades they can easily be substituted for mirrored or stained glass, while at the same time generating electricity. In addition, they could even perform additional functions, such as providing shading.
Traditionally, PV modules or PV arrays have been mounted on special support structures. However, they can also be mounted on buildings, or become an integral part of the buildings, or even be made an integrated part of the building envelope thus creating a natural on-site link between the supply and demand of electricity. Through the use of photovoltaics the consumption of power plant based electricity may be significantly reduced. The buildings may even be turned into small distributed net electricity producers and, as such, offer increasing benefits to all.
Once put in the building context, photovoltaics should not be viewed only from the energy production point of view. Because of the physical characteristics of the PV module itself, these components can be regarded as multifunctional building elements that provide both shelter and power.
In building-integrated solar power applications, the cost per unit area of the solar power elements is of great importance, since these materials can act as a substitute for other building materials. The effective additional cost per unit area of the building-integrated solar power elements is the difference between the price of solar modules and the material they could replace. A solar electric grid-connected system cost is almost the same per square meter as prestige facade materials, such as marble or other dressed stone. In suitable cases, where the two material costs are roughly the same, the added bonus of BIPV is that the solar electricity comes free of charge.
Demands are being placed on architects, engineers and the construction industry to develop more environmentally sustainable buildings with better energy efficiency. On the other hand, people want to live and work in surroundings that are attractive. Solar BIPV systems are the ideal solution uniting both criteria, while offering a variety of new approaches.
The imagination of the architect is the only limitation on how some of the various BIPV products that exist on the market today, could be integrated into the building envelope. Numerous building integration techniques could be utilized for the seamless BIPV module incorporation (Figure below).