Heating houses by sunlight
Facts about PV cells
- The production of photovoltaic cells has increased dramatically in recent years. In 1971, just 0.1 megawatts were shipped worldwide. By 1981, it was 7.8 megawatts, and in 1998 it had risen to 151.7 megawatts (a rise of 21% compared with 1997).
- The main producer is the United States, with 54 megawatts in 1998, followed by Japan and Europe.
- PV cells are mostly used for remote, non-residential power supply.
- Some countries have introduced tax incentives for solar rooftop systems. That, plus a fall in the factory price of cells, has led to a massive increase in their use.
- In Japan, 12,000 customers took advantage of incentives to install systems between 1994 and 1998.
- The European Union and the United States have introduced Million Roofs programmes, designed to encourage both solar electric and solar heating systems. These should be completed in 2010.