Page - 100 - in Clean Water Using Solar and Wind - Outside the Power Grid

100 Clean Water Using Solar and Wind: Outside the Power Grid The ratio between the theoretical maximum power generated by a solar cell (Pmax) and the product of the open circuit voltage and the short circuit current is called the fill factor, FF: FF P V I = ⋅ max OC SC The fill factor is typically around 0.75–0.8. Based on the four characteristic parameters, the conversion efficiency can be calculated and is defined at the ratio between the maximum generated power Pmax and the incident power (Pin) under standard testing conditions (STC): η = = ⋅ ⋅P P V I FF P max in OC SC in The efficiency is further examined in Chapter 8.3 and has typical values between 0.14 and 0.2. 8.3 CONVERSION OF SUNLIGHT TO ELECTRICITY Solar PV technology uses a semiconductor material to directly convert sunlight to electricity. In such a material the absorption of the light raises an electron to a higher energy state. This electron will then move from the solar cell into an external circuit. The electron delivers its energy in the external circuit and then returns to the solar cell. Almost all PV energy conversion uses semiconductor materials, where a p-n junction has been created, to allow this to happen. 8.3.1 Photovoltaic technologies There have been various photovoltaic technologies for solar cells developed to date: • Crystalline silicon technology, either monocrystalline or polycrystalline, • Thin-film, such as amorphous silicon, and • Organic cells. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user