The sun’s energy is harnessed by people in ways that are quite different from how it is used by animals. Though animals depend on the sun for their survival, the needs of people for light and heat are always in flux, and their utilization of the sun for purposes other than their primary purposes are entirely driven by a desire to prolong the use of the energy at little cost. It is important to recognize that most of the ways in which people have used the sun’s energy have been through the use of solar panels.
One of the earliest inventions and efforts to harness the sun’s power was to use the sun to warm water for people to use. This was probably the most common of all the uses of solar energy, with the largest number of different configurations used. This was likely most common in winter, when it is cold, and least common in summer, when it is hot.
Some ways of harnessing the sun’s power were more mechanical than chemical. In these, the sun was used to drive a pump, which would expel the liquid in a specific direction. By far the most common way of harnessing the sun’s energy was to position solar panels in a certain way so that the sun’s heat would heat a liquid being transferred to them. Often the liquid was water, but can also have been other fluids, which was why they were heated with the sun’s heat. The sun’s heat would transfer through the liquid, and the transfer of heat energy through the liquid could be used to drive a pump that would expel the liquid into a container.
This type of arrangement would have been obvious to early man, who was aware of the chemistry of the sun’s rays and its ability to be transferred into a liquid form. One of the first things that were known to be driven by solar energy was the drying of sails for sailing ships. Before man invented mechanical means of drying the sails, they were often damp and over time foul and rot. Through trial and error, man’s ability to make the sails of sailing ships dry quickly became an important method of sailing. By the end of the 12th century, this technology had advanced to the point where dry sails could be produced at reasonable cost. By the middle of the 14th century, large scale production of sails was common and became a means of transportation for those not interested in sailing.
Other examples of how the sun’s power could be harnessed include the harnessing of the sun’s energy in solar boilers, solar collectors, solar heated furnaces and solar ovens. In Europe, in the late 13th century, the use of solar energy was the primary means of heating water for the residents. In many parts of Europe, the use of solar water heaters was the primary method of heating water in the homes. It wasn’t until the 20th century that the use of solar water heaters started to decline, due to improvements in water heater technology.