Page - 57 - in Clean Water Using Solar and Wind - Outside the Power Grid

Water supply 57 that is up to 10 m deep. Again using (4.2), we find that the hydraulic energy is: Q MJ kWhhydr = ⋅ ⋅ ⋅ ≈ ≈40 10 1000 9 81 4 1 1. .J Assuming eight hours of sunshine, 80% motor-pump efficiency and 10% pipe loss the required electric power would be 0.19 kW. In other words, a large safety margin is assumed. Typically, 40 m3 of water per day is sufficient to irrigate up to one hectare of land planted with regular crops. 4.5 COMPONENTS IN A SOLAR PV PUMPING SYSTEM The solar panels make up most of the cost in a solar PV pumping system, while the pump usually only represents a marginal cost. Of course, the size of the energy supply depends on the required flow rate (m3/hour), and the solar irradiance. 4.5.1 Solar panels One of the major advantages of solar flat panels is that they can produce economically interesting quantities of energy without the need to track the sun’s position. The reduced demand for maintenance due to the lack of moving parts is reflected in a better overall economic result. Typically, for most solar panels it is guaranteed that the module will produce 90% of its rated output for the first ten years and 80% of its rated output for up to 25 years. This is an outstanding operational life, longer than that for most other equipment. The limited complexity of mounting and operating a solar PV system (compare Chapter 8) and the safety of the solar cells in combination with the manufacturing costs are all factors in the success of the expansion of solar PV. Of course, if the equipment is in a remote area the commercial value of the guarantee may be quite limited. However, the fact that such a guarantee is still given is an indication of the reliability of the system. 4.5.2 Inverters and pump controllers Solar panels deliver a direct current (DC) and the pump can be either a DC or an AC type. For an AC pump the DC from the solar panels must Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user