Generation expansion planning consists of finding the optimal long-term plan for the 5 construction of new generation capacity subject to various economic and technical constraints. It 6 usually involves solving a large-scale, non-linear discrete and dynamic optimisation problem in a 7 highly constrained and uncertain environment. Traditional approaches to capacity planning have 8 focused on achieving a least-cost plan. During the last two decades however, new paradigms for 9 expansion planning have emerged that are driven by environmental and political factors. This has 10 resulted in the formulation of multi-criteria approaches that enable power system planners to 11 simultaneously consider multiple and conflicting objectives in the decision-making process. 12 More recently, the increasing integration of intermittent renewable energy sources in the grid to 13 sustain power system decarbonisation and energy security has introduced new challenges. Such a 14 transition spawns new dynamics pertaining to the variability and uncertainty of these generation 15 resources in determining the best mix. In addition to ensuring adequacy of generation capacity, it 16 is essential to consider the operational characteristics of the generation sources in the planning 17 process. In this paper, we first review the evolution of generation expansion planning techniques 18 in the face of more stringent environmental policies and growing uncertainty. More importantly, 19 we highlight the emerging challenges presented by the intermittent nature of some renewable 20 energy sources. In particular, we discuss the power supply adequacy and operational flexibility 21 issues introduced by variable renewable sources as well as the attempts made to address them. 22 Finally, we identify important future research directions.

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A major drawback with active dual axis solar tracking systems is that the power used by the driving mechanism is often drawn from the output power of the solar panel itself. The net energy gain of the photo voltaic panel is therefore less than its maximum value. This work presents a novel design which uses a three fold strategy to minimize the power consumed by the tracking mechanism whilst maintaining the power out put of the photovoltaic panel near its optimal value. The results reveal that the improved tracking system has a significant energy gain of about 43.6% as compared to a fixed photovoltaic panel. Experiments further show that an increase of 1.6% in energy output is achieved over conventional precise dual axis tracking system.

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An accurate assessment of the amount solar radiation incident at specific locations is highly complex due to the dependence of available solar radiation on many meteorological and topographic parameters. Reunion Island, a small tropical French territory, intends to deploy solar energy technologies rapidly. In this context, the variability and intermittency of solar irradiance in different regions of the island is of immediate interest if the generated energy will be integrated in the existing energy network. This paper identifies different features of spatial and temporal variability of daily global horizontal irradiance (GHI) observed on Reunion Island. For this purpose, trends in the mean daily as well as seasonal variability of GHI were investigated. Furthermore, the intermittency and multifractal behaviors of the spatial daily GHI change were examined. Analyzing this daily variability is crucial to day-ahead forecasting of solar resource for better managing solar integration in the power grid, particularly in small island states with isolated power systems. Results revealed that the difference in cumulative GHI for two successive days ranges between −10 and 10 kW/m2/day while the highest and lowest variability of daily change occurs during summer and winter, respectively. The decorrelation distance, which gives a measure of the distance over which the variability at distinct geographic locations become independent of one another at a given timescale, was also calculated. It was found that the average decorrelation distance for day-to-day GHI change is about 22 km, a smaller value than that calculated by the previous studies using much sparser radiometric networks. The Hurst exponent, fractal co-dimension, and Lévy parameter, which describe solar radiation intermittency, were also evaluated for Reunion Island.