Seite - 99 - in Clean Water Using Solar and Wind - Outside the Power Grid

Solar PV 99 mm2 it typically reaches almost nine amps under standard conditions of 1  kW/m2. If the cell electrodes are disconnected, then there is no current flowing through the external circuit. The voltage under this condition is called the open circuit voltage (VOC) and is the maximum voltage that a solar cell can deliver. Typically, the value for commercial solar cells is of the order 0.4–0.6 V. The relation between the short circuit current and the open circuit voltage is illustrated by Figure 8.1. Voltage Current Short circuit current Open circuit voltagePower Figure 8.1 Principal relation between the current and voltage in a solar cell. The short circuit current ISC is obtained by zero voltage and the open circuit voltage VOC is reached by zero current (=open circuit). The maximum output power is reached by a certain combination of current and voltage. The maximum power – called the peak power Pmax (indicated as Wp or kWp) – from a cell can be delivered at specific values of the output voltage and the corresponding current. This is illustrated in Figure 8.1. Naturally the electric circuitry should be designed so that the cell can deliver peak power under the given external conditions. Typically, a solar cell of 150 ⋅ 150 mm2 can deliver a maximum power exceeding 5  W or of the order 200 W/m2. Solar cells can deliver between 35 and 200 W/m2. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user