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Solar water heating (SWH) systems comprise several innovations and many mature renewable energy technologies which have been accepted in most countries for many years. SWH has been widely used in Israel, Australia, Japan, Austria and China and co. 
Roof-mounted close-coupled thermosiphon solar water heater. Hot water heated by the sun is used in many ways. While perhaps best known in a residential setting to provide hot domestic water, solar hot water also has industrial applications, e.g. to generate electricity . Designs suitable for hot climates can be much simpler and cheaper, and can be considered an appropriate technology for these places. The global solar thermal market is dominated by China, Europe, Japan and India. 
A solar hot water heater installed on a house in Belgium Residential solar thermal installations fall into two groups: passive (sometimes called "compact") and active (sometimes called "pumped") systems. Both typically include an auxiliary energy source (electric heating element or connection to a gas or fuel oil central heating system) that is activated when the water in the tank falls below a minimum temperature setting such as 55°C. Hence, hot water is always available. The combination of solar water heating and using the back-up heat from a wood stove chimney to heat water can enable a hot water system to work all year round in cooler climates, without the supplemental heat requirement of a solar water heating system being met with fossil fuels or electricity. When a solar water heating and hot-water central heating system are used in conjunction, solar heat will either be concentrated in a pre-heating tank that feeds into the tank heated by the central heating, or the solar heat exchanger will replace the lower heating element and the upper element will remain in place to provide for any heating that solar cannot provide. However, the primary need for central heating is at night and in winter when solar gain is lower. Therefore, solar water heating for washing and bathing is often a better application than central heating because supply and demand are better matched.In many climates, a solar hot water system can provide up to 85% of domestic hot water energy. This can include domestic non-electric concentrating solar thermal systems. In many northern European countries, combined hot water and space heating systems (solar combisystems) are used to provide 15 to 25% of home heating energy. There are records of solar collectors in the United States dating back to before 1900, comprising a black-painted tank mounted on a roof. In 1896 Clarence Kemp of Baltimore, USA enclosed a tank in a wooden box, thus creating the first ’batch water heater’ as they are known today. Although flat-plate collectors for solar water heating were used in Florida and Southern California in the 1920s there was a surge of interest in solar heating in North America after 1960, but specially after the 1973 oil crisis. Main article: Solar power in Israel 
Passive (thermisiphon) solar water heaters on a rooftop in Jerusalem Flat plate solar systems were perfected and used on a very large scale in Israel. In the 1950s there was a fuel shortage in the new Israeli state, and the government forbade heating water between 10 p.m. and 6 a.m.. Levi Yissar built the first prototype Israeli solar water heater and in 1953 he launched the NerYah Company, Israel’s first commercial manufacturer of solar water heating. Despite the abundance of sunlight in Israel, solar water heaters were used by only 20% of the population by 1967. Following the energy crisis in the 1970s, in 1980 the Israeli Knesset passed a law requiring the installation of solar water heaters in all new homes (except high towers with insufficient roof area). As a result, Israel is now the world leader in the use of solar energy per capita with 85% of the households today using solar thermal systems (3% of the primary national energy consumption), estimated to save the country two million barrels of oil a year, the highest per capita use of solar energy in the world.. 
New solar hot water installations during 2007, worldwide. The world saw a rapid growth of the use of solar warm water after 1960, with systems being marketed also in Japan and Australia Technical innovation has improved performance, life expectancy and ease of use of these systems. Installation of solar water heating has become the norm in countries with an abundance of solar radiation, like the Mediterranean, and Japan and Austria, where there Colombia developed a local solar water heating industry thanks to the designs of Las Gaviotas, directed by Paolo Lugari. Driven by a desire to reduce costs in social housing, the team of Gaviotas studied the best systems from Israel, and made adaptations as to meet the specifications set by the Banco Central Hipotecario (BCH) which prescribed that the system must be operational in cities like Bogotá where there are more than 200 days overcast. The ultimate designs were so successful that Las Gaviotas offered in 1984 a 25 year warranty on any of its installations. Over 40,000 were installed, and still function a quarter of a century later.
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