Solar Power Generation

Paul Breeze

• Publisher: Academic Press
• Year: 2016
• ISBN:
  9780128040546
• Topic: Tecnologia e ingegneria
• Subtopic: Ingegneria elettronica e telecomunicazioni

Solar Power Generation is a concise, up-to-date, and readable guide providing an introduction to the leading renewable power generation technology. It includes detailed descriptions of solar photovoltaic and solar thermal generation systems, and demystifies the relevant solar energy technology functions in practice while also exploring economic and environmental risk factors. Engineers, managers, policymakers, and those involved in planning and delivering energy resources will find this reference a valuable guide to help establish a reliable power supply to address social and economic objectives.

• Focuses on the evolution and developments in solar energy generation
• Evaluates the economic and environmental viability of the systems with concise diagrams and accessible explanations
• Demystifies the relevant solar energy technology functions in practice
• Explores economic and environmental risk factors

Chapter 1

An Introduction to Solar Power

Abstract

Solar power is the Earth’s most important source of energy. It is responsible for the biomass on the Earth and the fossil fuels within it, as well for driving the weather systems responsible for rain and wind. The Sun can be used to generate electricity in two ways, either by using its heat as a heat source, or by utilizing its light in a solar cell. Solar power is an intermittent source of energy and cannot alone provide a continuous source of electrical power. The development of both solar cells and solar thermal power generation can be traced back to the 19th century. At the end of 2014 there were close to 180 GW of solar generating capacity around the world.

Keywords

Solar energy; solar cells; solar thermal power generation; global solar capacity; history of solar power

Solar power is the most important energy resource for life on Earth. The energy in sunlight has driven the evolution of life upon our planet from the earliest tiny organisms through to the plants that have provided food for higher organisms, and eventually for the human race. As a consequence, solar energy is responsible for many of our common energy sources. All the biomass upon the Earth has been created using energy from the Sun to drive photosynthesis, capturing carbon dioxide from the atmosphere and using it to produce organic compounds. The resulting material includes both biomass growing on the Earth today and the fossil fuels that are the remains of ancient biomass buried within the Earth over time, fuels that are now being burned to generate electricity and release the captured carbon dioxide back into the atmosphere.

From the perspective of energy sources, the importance of solar energy is wider still. Sunlight is the heat source that drives the Earth’s weather systems. It evaporates the water that generates rainfall, and is therefore responsible for hydropower. The Sun also provides most of the energy that drives the global winds, so it is responsible for wind power. Wave power, a product of the Earth’s winds, is indirectly a product of solar power too, as is ocean thermal power. In fact, with the exceptions of nuclear, tidal, and geothermal power, all the major sources of electricity on Earth can be directly or indirectly linked back to the Sun.

While solar energy is responsible for all these exploitable forms of energy, sunlight can also be utilized directly to generate electricity. This can be carried out in two ways. The conceptually simplest method is to use the heat energy contained in solar radiation as a heat source, collecting the Sun’s rays and capturing the heat so that it can be used to drive a heat engine such as a steam or gas turbine. This type of power generation has a long history, and today solar thermal power stations are being built in many parts of the world. The second important way of exploiting solar energy to produce electricity is in a solar or photovoltaic cell. The latter is a solid-state device, closely related to the transistor or microchip, that can absorb sunlight and turn the absorbed light energy into electrical energy. Solar cells use a different part of the solar spectrum from solar thermal power stations, relying on higher energy and shorter wavelength radiation, whereas solar thermal plants use longer wavelength infrared and near-infrared light.

The commercial use of solar energy to generate electricity took off slowly during the last three decades of the 20th century. The main stimuli for the development of both solar thermal and solar photovoltaic technologies were the oil crises of the 1970s. Solar cells soon found a use in applications such as powering satellites and providing remote power. Then a number of nations began funding solar rooftop installation programs, beginning in the early 1990s, to promote the use of solar cells although the cost remained high until the first decade of the 21st century. Since then costs have fallen dramatically and solar cells are becoming cost-effective in a much wider range of applications. For the future, solar cells potentially offer the most cost-effective and simple power-generating technology for providing renewable electric power.

Solar thermal technology has developed much more slowly than solar cells. After an initial burst of activity during the late 1980s and early 1990s, commercial application of the technology was virtually abandoned until the first decade of the 21st century. A number of commercial power plants have since been built but costs still remain relatively high. In spite of that, solar thermal technology has the potential to make an important contribution to global energy production.

The Sun provides an intermittent source of energy at any fixed point on the Earth’s surface because it is only available during daylight hours. In addition, the intensity of solar radiation varies with both time of day and atmospheric conditions. As a consequence, solar energy cannot on its own provide a continuous source of electrical power. For small or off-grid applications, solar cells can be backed up with a battery energy storage system that is charged during the day to provide power during hours of darkness. For larger and grid-based solar generation, there is normally an alternative generator available to provide power when solar power is not available.

The amount of electricity generated by solar sources is still relatively small. According to the International Energy Agency (IEA), solar photovoltaic systems generated around 0.85% of global generation in 2013. This was expected to rise to around 1% in 2014. Solar thermal power plants generate about 3% of the amount produced by solar cells, or a further 0.03% of global generation.

The History of Solar Power

The exploitation of solar thermal energy can be traced back at least 29 centuries to the 7th century BC when the use of magnifying glasses was first recorded. This was followed in the 3rd century BC by the use of mirrors to concentrate the rays of the Sun, using the heat generated to light torches, often for religious ceremonies. The Greek scientist Archimedes is reputed, around 214–212 BC, to have used giant mirrors to focus light on the ships of Roman invaders who were attacking his home city of Syracuse in Sicily, apparently setting the wooden vessels on...