The history of solar power

For billions of years, the power of the Sun has been harnessed by algae and plants to produce their vital building blocks glucose and cellulose. A byproduct of this process, which is called photosynthesis, is oxygen, a substance required by all multicellular life on Earth. Although by far not as long as other forms of life, humans have also been enjoying the advantages of solar energy throughout history. The ancient Egyptians used solar heat to bake mixtures of mud and straw into hard bricks for construction. The Greeks and Romans used clever architecture to make use of the Sun’s ability to provide light and heat in a building. This form of solar power is called passive solar energy and is stillused in construction today. A more active application of solar energy was used by the Greeks, who as early as 200 B.C. used bronze shields to focus the sun’s rays on Roman ships, setting them on fire. A similar, although more peaceful, approach was used by the Chinese in 20 B.C. to light torches for religious services.

In 1767, the world’s first solar collector was constructed by Swiss scientist Horace de Saussure. His collector, the so-called hot box, allowed people to cook food during desert expeditions. The true foundation for solar photovoltaic energy was however laid in 1839, when French scientist Edmond Becquerel discovered the photovoltaic effect. His work was expanded upon in 1876, when William Grylls Adams and Richard Evans Day discovered how to turn light into electricity using the metal selenium. Seven years later in 1883, the American Charles Fritts described the first working solar cell. In 1891, the first commercial solar water heater is patented by an American inventor in Baltimore.

The 1900s

In the early twentieth century, only little progress was made in the development of practical solar power. Some important theoretical work was however done in this period.

In the first years, photovoltaic technology was still prohibilitly expensive: solar power was priced at $300/watt at the time, compared to 50 cents a watt for regular power! Consequently, solar cells were only used for a limited number of novelty items, such as miniature ships and beach radios.

The 2000s

Note: due to the large and complex history of solar power, the above history is an excerpt. For a more complete overview, see the solar timeline by the US department of energy.