Edinburgh Napier University

  Worldwide, over 1.1 billion people have no access to electricity. The consequences for the affected people include health hazards from fuels used for lighting, limits to learning when it gets dark, a short productive day and high expenditures on lighting alternatives. Since 85\% of affected people live in rural areas in developing countries, increasing access to electricity through grid supply is logistically and financially challenging. As a potential solution to this issue off-grid solar chargers have been gaining popularity. This technology is under continuous development to achieve lower costs, faster battery charge and more electricity generation to prolong light hours. This review contains a comprehensive analysis of possible improvements to solar lights and the role solar PV concentrators can play in it. It aims to provide the reader with a critical comparison of existing solar PV concentrators and to consider the advantages and drawbacks if applied to portable solar systems used in developing countries. From this review, static nonimaging concentrators have been identified as best suited since they are easy to operate and maintain and have shown high reliability. A detailed comparison of existing static nonimaging concentrators is presented in this work and their suitability for being deployed in portable solar systems in developing countries is evaluated. It concludes that the existing designs need adjustment if to be used for this purpose. Thus, novel concentrator designs for portable solar systems for developing countries are needed to facilitate more off-grid solar power generation. It is the aim therefore of this review to stimulate more research in this field.