A brief history of solar (photovoltaic) cells

Polycrystalline solar panel.
Source: Photo courtesy of RISE

A French physicist, Edmund Becquerel, first noticed the photovoltaic effect in 1839. He exposed two electrodes in a weak electrolyte or conducting solution (such as salt water) to light, and noticed the appearance of an electrical voltage.

In 1877, Charles Fritts constructed the first solar cells by coating a semiconductor, selenium, with an ultrathin nearly transparent layer of gold. These cells were very inefficient, turning under 1 per cent of absorbed light into electrical energy.

Large improvements in solar cells didn’t occur until scientists had a better understanding of how the photovoltaic effect worked. This occurred by the 1930s when cells were used in light-sensitive devices, such as photometers, used to detect light levels for photographers.

The solar cells used in these photometers could still only turn less than 1 per cent of light into electricity, making them good for sensing light levels but not very useful for generating electricity.

An American researcher, Russell Ohl, developed the first silicon-based solar cell in 1941. A more advanced version in 1954 was capable of converting 6 per cent of sunlight into electricity.

By the late 1980s, these silicon cells, as well as solar cells made using gallium arsenide, were able to convert more than 20 per cent of the light they absorbed into electricity.

And by 1989, a ‘concentrator’ solar cell, where sunlight was concentrated onto the cell surface using lenses like a telescope, reached a 37 per cent conversion from light into electricity.

Solar cell technology was first used in satellites that required a continuous source of energy. These cells were made of crystalline silicon.

The cells were very expensive at first and were not considered affordable for widespread use. As time went on however, more advanced technology brought the cost down. More people also became interested in the development of these photovoltaic cells because they are an efficient, clean source of electricity.