Solar renewable energy, often referred to as photovoltaic power, is renewable electricity generated by the sun. Semi-conductors in solar cells produce electricity when photons strike electrons. Photovoltaics are found in a wide variety of situations: from renewable electricity generation to off-grid power generation, including everything from powering calculators to charging the batteries on cars and boats.

Solar renewable energy should not be confused with solar thermal technology. Solar thermal panels look very similat to solar cells but produce no electricity. They are often used to heat water, which has a wider heat application.

Solar renewable energy can be found on small-scale residential or commercial settings (to power homes or small businesses) though to large solar parks which are used to generate renewable electricity.

The photovoltaic effect was first discovered by French physicist Alexandre-Edmond Becquerel in 1839 and the first solar cell was built in 1883 by an American inventor, Charles Fritts. Photovoltaics have attracted the attentions of other famous scientists, including Russell Ohl and Albert Einstein.

Although the theory of photovoltaics has existed since the mid-nineteenth century, it is only comparatively recently that solar renewable energy has been realised on a large scale. The technology made great advances during the Space Race, when solar cells were attached to spacecraft and satellites to produce solar renewable energy.

The 1980s saw growth in solar renewable energy but, since 2002, there has been an average yearly increase of 20% in solar renewable energy production  as technological advantages, government policy and awareness of climate change have made solar renewable energy a more attractive investment opportunity.

In theory, energy from the sun is the most abundant renewable electricity source on the planet and could technically supply the world’s energy needs many times over. Whilst available across the planet, solar renewable energy varies in effectiveness from place to place according to the intensity of the sun at certain latitudes, the comparative hours of daylight and climatic variations (how cloudy a certain location is and often the full power of the sun reaches the ground).

The optimal location for solar renewable energy is located in a wide band extending north and south of the equator, broadly including all of Africa and Oceania and large parts of North and South America and excluding much of Europe and northern Asia. Some European countries may install large solar renewable energy parks in the Sahara for import into Europe.

It is perhaps somewhat surprising that some of the world’s largest solar renewable energy parks are found in Canada and Germany, with Germany leading the way as the largest solar renewable energy producer in the world. Spain is catching up quickly, largely thanks to a generous feed-in tariff system.

Here in the UK, we have limited capacity for photovoltaic renewable energy on a large scale (see our wind renewable energy and biomass renewable energy pages for our real specialities). However, the introduction of Feed-in Tariffs in April 2010 has seen solar renewable energy grow in popularity, particularly on a small scale, domestic setting.

Depending on the global location, solar renewable energy can be a highly effective technology. Once it has been set up, it is generally easy to run and maintain and off-grid renewable electricity generation is a tried-and-tested success.

The sun's movements are predictable so the energy source is guaranteed but affected by climatic conditions.

Solar renewable energy can be installed on a variety of scales, hence the popularity amongst householders. There is almost nothing which excludes the site-selection of a solar cell and an abundance of unused roof-space means solar renewable energy can be installed on a large scale in urban environments, unlike other technologies.

The capital outlay (i.e. cost) of buying and installing solar cells can be prohibitive, particularly for the individual. Current solar renewable energy generating units are guaranteed for around 20 years. Whilst generally they ‘pay back’ their installation costs, it may still be much longer than other mainstream renewable electricity sources.

Whilst the technology is well-understood and operating costs are low, the materials used in the construction of solar cells are advanced. Not only is this responsible for the expense of solar panels but it also raises questions over the long-term sustainability of solar renewable energy, as well as the recycling of materials at the end of a solar panel’s life.