Solar photovoltaic (PV) systems directly convert solar energy into electricity.
The basic building block of a PV system is the PV cell, which is a semiconductor device that converts solar energy into direct-current electricity. PV cells are interconnected to form a PV module, typically up to 50 to 200 Watts. The PV modules, combined with a set of additional application-dependent system components (e.g. inverters, batteries, electrical components, and mounting systems), form a PV system. PV systems are highly modular; i.e. modules can be linked together to provide power ranging from a few watts to hundreds of megawatts.
The most established solar PV technologies are crystalline silicon-based systems. Thin-film modules, which can also consist of non-silicon semiconductor material, represent about 10% of the global market. Concentrating PV, where sunlight is focused onto a smaller area has just entered full market deployment. Concentrating PV cells have very high efficiencies of up to 40% - but only with respect to direct normal irradiance. Other technologies, such as organic PV cells, are still in the research phase.
Solar PV combines two advantages. On the one hand, module manufacturing can be done in large plants, which allows for economies of scale. On the other hand, PV is a very modular technology. It can be deployed in very small quantities at a time. This quality allows for a wide range of applications. Systems can be very small, such as in calculators, up to utility-scale power generation facilities.
Compared to concentrating solar power (CSP) and CPV, non-concentrating (“1-sun”) PV has the advantage that it uses not only direct sunlight but also the diffuse component of sunlight, i.e. solar PV produces power even if the sky is not completely clear. This capability allows the effective deployment in many more regions in the world than for CSP.
Because PV generates power from sunlight, power output is limited to times when the sun is shining. However, as IEA analysis under the Grid Integration of Vraiable Renewables (GIVAR) project has highlighted, a number of options (demand response, flexible generation, grid infrastructure, storage) exist to cost-effectively deal with this challenge.
Solar PV generation and projection by region
IEA, (2014), Medium-Term Renewable Energy Market Report 2014, OECD/IEA, Paris
On 29th of September 2014 the IEA released Technology Roadmap: Solar Photovoltaic Energy - 2014 edition.
For more information on solar PV technologies please also refer to Solar Energy Perspectives.