Photovoltaics integrated into buildings could be among the first mans to provide solar electricity into the grid on a massive, multi-MW scale.

Solar energy and buildings have been long associated. Millions of houses derive their hot water using solar collectors, and the principles of passive solar design have been used in architecture for centuries. Consumption of energy within buildings is a major component of national energy demand, being typically 20%-30% of the total primary energy consumed in IEA member countries. The share of electricity in buildings' energy balance is also increasing. This is due to improved climate control and energy efficiency measures, which reduce thermal energy demand, but at the same time increased use of consumer electrical appliances and equipment. There is growing interest in the use of innovative building components to reduce the electrical energy imported into the building. The use of PV as a solar building technology is now receiving widespread attention.

Stand-alone PV systems are well established, but the new emphasis by utilities, governments, and others is on grid-connected applications. There is a widely accepted view that distributed photovoltaic systems, which generated electricity at the point of use and are grid-connected, will be the first to reach widespread commercialization. Particularly attractive are PV power systems for individual buildings.

Germany has undertaken the most comprehensive programme to install PV systems on individual houses. The 1000 Roofs Programme was launched in 1990. The Ministry of Research and Technology (BMFT) and local State Governments provided subsidies amounting to 70% (except in Saarland, which considered 50% to be sufficient). The maximum installed system price allowed for determination of the subsidy was approximately USD 16/Wp. Interest in the programme was overwhelming with 60 000 individuals expressing their interest. Eventually, 4000 applications were received and 2250 approved. All the installations were completed by the end of 1994, amounting to almost 6 MWp of grid-connected rooftop PV capacity. All the installations are recording PV performance, and additionally 100 of the installations, spread evenly across Germany, are being intensively monitored. This programme constitutes the largest broadly based test of PV in the world.

Within Japan's New Sunshine Programme there is intensive discussion of an ambitious project to support the installation of 70 000 rooftop PV systems over a ten-year period. Subsidies for the first 700 systems have been approved. Building integration of PV, where the PV elements are a part of the building, forming the roof or wall, is exciting architects and developers world-wide. There have been some thousands of projects where PV modules have been installed on buildings. But now PV roof tiles and façade cladding panels are on the market as well as being the subject of intense research and development.

The IEA and solar electric buildings The International Energy Agency has pioneered solar electric buildings. The Solar Heating and Cooling Programme, which is mainly concerned with active and passive solar in buildings, added a PV in Buildings project, Task 16, in 1990. Thirteen countries are co-operating in a broad range of R,D&D within the programme, for example, each country has designed and built a Demonstration PV Building, which is being monitored. It is expected that a new project on PV in the Built Environment (Task 7) will be launched within the IEA  PVPS Programme in the spring of 1996, following the completion of Task 16.

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