With over six months of sunshine a year many parts of Israel are perfectly situated to make use of solar energy. As a nation Israel does not have any natural energy resources and most it's fuel and power come from fossil fuels such as coal and oil which have to be imported. This leaves Israel vulnerable to her less than sympathetic neighbours. Because of this it is not surprising that Israel should encourage the use of solar energy.

Hot water heating.
You are not long in Israel before you notice the prolific number of solar water heaters atop many of the houses. These consist basically of 150 litre insulated storage tank and a 2 sq.m. flat panel which is where the actual heating is done. Most of these have backup heating elements but it is rare for these to be used. Larger pump driven systems, can be found on high-rise housing projects, on several kibbutzim and at a number of industrial plants around the country.

Passive Solar Systems.
Although Israel is commonly perceived as being an extremely "hot" country winters can be cold, particularly in Jerusalem and other highlands - including those in the Negev desert.

The first passive solar house in Israel is said to have been constructed from sun-dried adobe bricks on the Sde Boker campus of Ben-Gurion University. Since its completion in the late 1970s the basic principles of passive solar design have been widely adopted by architects all over the country.

Most passive heating is created through the design of the buildings rather than using more active measures like solar space heating or geo-thermal units. The principles behind Israel passive solar design are based on globally accepted rules. Large south facing windows with smaller south facing windows. Thermal mass in the form of adobe brick and walls and a well insulated core.

Solar PV Cells.
The high cost of PV cells has restricted the widespread use of solar PV cells for domestic applications. They are more commonly used in bus shelters and some other forms of public lighting.

PV cells are also used in research and development and creating solar energy plants.

Solar Saline Ponds
The basic idea involves a pond of salt water, about 2 m. in depth. There are basically three layers to this pond -dense salty water at the bottom, less dense salty water and fresh water on the top. These are artificially maintained. Absorption of solar radiation by the floor of the pond heats the lower depths of water which are prevented from rising by their high density relative to the upper layers.Temperatures at the bottom of the pond can reach almost 100 degrees centigrade.

The effect is that solar energy is stored in these ponds and can be released at will. The Ormat Corporation who pioneered such ponds developed a special low-temperature turbine which enables the hot pond water to convert an organic fluid to vapor which drives a turbine and thus produces electricity.Ormat's organic fluid turbine has turned out to have such a long life-time, partly because it is a totally sealed unit, that such devices are to be found all over the world in situations where low-temperature heat sources are available and electric power is required.

Parabolic Trough Collectors
The now defunct Luz corporation was well know for it's parabolic trough convertors and was tasked with developing the record-breaking, 12.5 MW electricity-generating power station at Dagget, California. Luz went on to construct six 30 MW power plants, employing a larger size solar collector unit and even two 80 MW power stations which involved a third generation of yet larger solar collector units. All of these electricity-generating power plants were built in California and are active today.

A number of institutions conduct solar research today. Thes include Ben-Gurion University, Jerusalem College of Technology (high-efficiency, single crystal cells) and at Tel Aviv University (amorphous silicon thin layers),Technion Israel Institute of Technology and at the Weizmann Institute of Science.

These range from surveys on Solar radiation in the Negev through to the formation more efficient PV cells and alternative uses for solar energy - see the solar surgery above.

Solar-thermal power, another candidate technology for future power stations, is under investigation at Ben-Gurion University (parabolic troughs and a parabolic dish) and at the Weizmann Institute (solar furnace and central receiver tower). The Ben-Gurion University dish, is located at the BGNSEC, Sized at 400 sq.m. in area and is capable of concentrating the sun's rays up to 10,000 times. This is far higher than the concentration available from linear reflectors such as parabolic troughs and will accordingly permit a wide range of new research avenues to be investigated.

The Weizmann Institute Central Receiver Tower, on the other hand, consists of a field of 64 so-called "heliostat" mirrors, each of approximate area 50 sq.m. that re-direct the sun's rays to a boiler, or some other suitable receiver, mounted on a tower some 50 m. in height. The combined effect of so many mirror surfaces, when focused onto a relatively small central receiver, can obviously produce extremely high solar concentrations.

The Weizmann Institute tower should not, however, be confused with yet another tower concept that is under active development at the Technion. This idea involves pumping water to the top of a very high tower (1 km. or more) which would be located in a dry desert area. The water would evaporate and the down-draft created by falling, cooled, moist, air would then drive a special wind-turbine located within the tower. This, of course, is a secondary use of solar energy but one which, nevertheless, has intriguing possibilities.

Thanks to it's self reliance and need to develop technology for itself - Israel is now considered on of the experts in green technology and it's knowledge is widely sought to run projects throughout the world.