Aren't Solar Energy Systems too expensive?
The argument often put forward against the use of solar heating systems is that they are not economical. This often culminates in a flat out rejection of renewable energy. But have you ever asked yourself whether the expensive tile you have used on the floor has any utility? Or the new aluminum wheel rims on your car are economical? Or the electric geyser you are using is energy efficient? Other than that, you cannot forget that solar heating systems provide an important contribution to the use of environmentally friendly energy.

The inexpensive prices for conventional energy sources conceal the real facts. The consequential costs for environmental and health damages caused by their use (the so-called "external costs") are not included in their price and have to be payed for by the general public. You also have to consider, that the price for conventional energy sources will increase considerably in the near future, due to these resources running short.

The sun, however, supplies its energy free of charge. T he relatively high initial investment at first sight suggests that the systems are, in general, very expensive. But from the time of installation of the system on, there are no more operating costs, except for the negligible maintenance costs. Whoever invests in a solar system is also investing in the future.

1455 B.C. - A.D. 1419
During the reign of the Egyptian King Amenhotep III there were "sound statues" in the temples. The sun shining on the statues heated up the air inside them. This heating caused warm air to rise up through the statues. The sound came about when the air passed through the apertures. This effect occurred when the morning sun was shining on the statues. It became a morning signal. It is also recorded that in the burial chamber of Zari Memnon, son of Amenhotep III, the wellknown song of an artificial bird was actually caused by the early morning sun. In China descriptions have been found dating from the Han dynasty. These show concave bronze or copper mirrors that were used by the "Sun-kindler" to light the sacrificial lamps. Later attempts to harness solar energy include the story of the burning of the Roman fleet in 212 B.C According to Johannes Tetzes, a thirteenth-century writer, Archimedes set fire to the enemy
fleet using burning glasses made of small square movable mirrors on a hinge system. When these were positioned to face the rays of the sun, the rays were reflected towards the Roman fleet. At a distance of a bowshot the fleet was set on fire and destroyed after the sails had been ignited. Whether this story is true or not, it is a fact that solar devices were developed and built early in history. As the number of them grew, man's mythic relationship with the sun altered. Early religious and cultural attitudes and belief in the sun began to disappear, whereas by the seventeenth century there was a greater focus on science than on superstition and magic.

1300 - 1600
The Renaissance - an age of science and art - brought forth many solar-energy inventions. One of the most original solar inventions was built by Salmon de Caus in France. He used the sun to heat air to pump water in his "sun engine". Although this was a very simple mechanical use of solar energy, it was another 200 years before the "sun engine" was rediscovered.

1750 _ 1800
Renaissance use of solar energy was mostly in the form of "toys" with no practical application. This trend however took a turn in the latter half of the eighteenth century when solar furnaces capable of smelting iron, copper, and other metals were constructed out of burnished iron, glass lenses, and mirrors. These solar furnaces were in use in Europe and the Middle East. One of them was designed by the French scientist: Antoine Lavoisier. It achieved temperatures of 1,750°C and was made up of one lens with a diameter of 130 cm and a secondary lens with a diameter of 20 cm.

1820 _ 1830
During this period several hot-air engines were developed. The famous two- cylinder Stirling air engine was ideal for solar use, even though it was not originally developed for this purpose. A wondrous selection of such machines was built during the next hundred years. They drove everything from printing- presses and electric light to distillation processes. In 1826 the Swedish engineer John Ericsson invented a hot-air engine. He used a 300 horsepower version to power a paddle-steamer. Later he modified the engine and ran it using solar energy. The Swiss scientist Horace de Saussure is credited with inventing the world’s first solar collectors or solar hot box 1767.