The pace of new developments in solar energy has become frenetic in the last decade. Technological change of course is often linked to commercial demand or human need. While the link between solar energy and heating is as old as human awareness itself, the connection between sunlight and electricity is only 160 years old. The basic science of what was to become known as photovoltaic technology first emerged in 1839 when a young Frenchman, Alexandre Edmond Becquerel, discovered that light cold be converted into electricity. His observations were made as he experimented with simple metal electrodes and an electrolyte and had little to do with modern PV materials, but the idea had been born.
It took 45 years before an American, Charles Fritts, found that wafer thin sections of a substance called selenium could convert light into electricity. Selenium, like silicon and germanium, is an element which is basically a non metal, but has some properties of being a metal.
5 years later, the first patent for a solar cell was taken out by another American, Edward Weston. There was little demand for such a low powered device at this time and it must be remembered that the world was awash with newly discovered oil and gas, and no doubt there seemed to be endless supplies of fossil fuels around, so a solar cell would have been little more than a curiosity.
In 1905, Albert Einstein not only published his well known theory of relativity, but contributed to the science of photo-electricity as well, publishing a paper describing his theory on the link between light and electricity which later was tested in true scientific style by experimental confirmation just 10 years later by a scientist called Robert Millikan. Einstein actually received a Nobel prize for his PV theory in 1922.
It wasn’t until the space age and the development of satellites and spacecraft that solar technology really took off in the 1950s and 1960s. Bell Laboratories in the U.S. discovered that silicon could also do what selenium could do and more efficiently. They soon began to manufacture more efficient solar cells, based on silicon technology and panels with these cells were used to provide power in space.
The sixties saw the emergence of bigger developments, with large PV arrays being put into used in remote places like lighthouses.
The seventies saw the first energy scare with a sharp restriction on the supply of crude oil by OPEC. Solar energy started to attract a lot more interest. Sharp, Kyocera and Solarex were all producing a variety of solar panels by this stage, with the cost of panels being dramatically reduced as well as the energy efficiency, i.e. the percentage of energy striking a panel being converted into useful electricity, getting better. Solar panels were now being used in a larger number of locations, such as marine navigation beacons and lights, railway crossings and many rural locations where the cost of providing mains electricity was prohibitive. It was becoming commonplace by the end of the seventies for yachts to use solar panels on their decks or cabin tops in place of often untrustworthy diesel engines.
The eighties and nineties saw the onset of widespread subsidy schemes in some more enlightened countries. Germany, Japan and California led the way in terms of overall support for the use of PV solar energy technology on rooftops. Concerns about greenhouse gas emissions and their effect on the global climate were steadily being confirmed by a mass of scientific evidence. The demand for environmentally friendly alternatives was rapidly growing.
In the U.K., solar energy for electricity generation only really began in earnest in the first decade of the 21st century with continuing worries about peak oil and the need to develop more environmentally friendly sources of power. The rate of solar rooftop installation began advancing with the cost of a solar kilowatt plummeting and parity with the grid price for electricity expected soon – even without subsidies.
One of the most recent developments has led to a marriage between solar electricity and thermal energy. PV panels by themselves often get too hot to be very efficient. It was discovered that by passing water over them the reduction in temperature could provide dual benefits: not only was the electricity generation more effective but hot water was produced, too. A PV-T hybrid panel, such as our “Solar Angel”, is a striking example of just where solar developments have progressed; the future generation of solar technology.
