Page - 32 - in Clean Water Using Solar and Wind - Outside the Power Grid

32 Clean Water Using Solar and Wind: Outside the Power Grid a system needs no inverter (see glossary) to convert the DC power to AC but requires battery backup for use during the night. The DC system can supply power directly to DC-powered appliances like LED lights, radios, TV sets and mobile phone charging units. For larger power ratings, needed for water pumping and cleaning, AC power will be needed. Then DC/AC inverters will be needed; see Chapter 4.5. 143 285 387 498 621 759 0 100 200 300 400 500 600 700 800 2017 2018 2019 2020 2021 2022 Figure 3.3 Predicted cumulative growth (in MW) of off-grid solar home systems in sub-Saharan Africa and developing Asia. The growth in mini- grids and industrial solar systems is of the same order of magnitude as the solar home systems. Data from IEA (2017b). The progress of solar home systems is largely attributable to highly efficient LED lamps. Professors Isamu Akasaki, Hiroshi Amano and Shuji Nakamura made the first blue LEDs in the early 1990s. This enabled a new generation of bright, energy-efficient white lamps, as well as colour LED screens. As the Royal Swedish Academy of Sciences said when presenting the 2014 Nobel Prize in Physics to this trio of scientists: “The LED lamp holds great promise for increasing quality of life for over 1.5 billion people around the world who lack access to electricity grids. Due to low power requirements, it can be powered by cheap local solar power.” Another contribution to quality of life is the comparison of the light from solar-powered LED lights compared to the light quality from kerosene wick lamps. A LED light of 2 W will produce 380– 400 lumens compared to 8–40 lumens for a kerosene wick lamp. The Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user