According to the International Energy Agency, nearly 20% of worldwide electricity is used up by lighting. This is equal to the total electricity nuclear power generates. Thus, it is needy to explore new technologies for direct use of sunlight via integrating daylight system to the building, which is cost-saving, environment-friendly, and a green solution rather than indirect conversion of electricity to lighting even from renewable sources. In this paper, we present a review on the existing technologies of daylighting systems up to date and how they can provide lighting in a building interior via collection and distribution of sunlight. Our review is a comprehensive study to embrace both passive daylighting system with stationary design and active daylighting system equipped with sun tracking. The economic feasibility, general challenges, and prospects of daylighting systems are also discussed to understand the existing problems that hinder the extensive deployment of daylighting systems. In conclusion, more research works are needed in improving the technological development of a daylighting system so that it is more affordable, environment-friendly, less energy-intensive, and easy to install and gives uniform illumination for the effective application in both commercial building and residential houses.

Optimization of the design of a nonimaging dish concentrator (NIDC) for a dense-array concentrator photovoltaic system is presented. A new algorithm has been developed to determine configuration of facet mirrors in a NIDC. Analytical formulas were derived to analyze the optical performance of a NIDC and then compared with a simulated result obtained from a numerical method. Comprehensive analysis of optical performance via analytical method has been carried out based on facet dimension and focal distance of the concentrator with a total reflective area of $120{\mathrm{m}}^2$. The result shows that a facet dimension of 49.8 cm, focal distance of 8 m, and solar concentration ratio of 411.8 suns is the most optimized design for the lowest cost-per-output power, which is US$1.93 per watt.