ABSTRACT
Solar photovoltaics (PV) are semiconducting materials that convert energy from daylight directly into electricity, and are now becoming a significant part of the electricity generation mix worldwide. However, the core technology is not so new; the photovoltaic effect was first described by Edmond Bequerel back in 1839 and in 1954 Daryl Chapin, Gerald Pearson and Calvin Fuller of Bell Laboratories produced the first solar cell as we know it, and its 4.5% conversion efficiency enabled this new technology to act as a viable power producer [1]. The first solar cells were prohibitively expensive [2], but fortunately a new market niche opened up their viability. Solar PV proved an ideal power source for the space programme and satellites, where its ability to harness the freely available solar radiation, while being comparatively lightweight and more reliable than chemical batteries, was advantageous [3]; the first solar-powered satellite was launched in 1958. Since that time, costs of PV have dropped, following a typical ‘technology learning curve’ where costs reduce with increased installed capacity. At first, solar PV was used for off-grid locations where it was more economically attractive than conventional fuels; as costs dropped further, PV became more widespread in on-grid locations. Grid-connected applications now make up the vast majority of the solar market, and they have been encouraged by national policy schemes to promote PV, of which the feed-in tariff scheme has been the most successful type worldwide. At the time of writing costs of PV at scale are ca. $1/W for a fully installed system, which has long been held as the price necessary for solar generated electricity to be economic in its own right, with ca. $0.10/kWh in sunnier locations [4]. Some subsidy is generally still required, but sunnier parts of the world can now install PV economically without subsidy (cost-parity) and Spain, for example, has installed solar PV farms without subsidy.
