A network of all sky imagers (ASI) enabling accurate and high-resolution very short-term forecasts of solar irradiance

The Eye2Sky network is a measurement network in north-western Germany consisting of multiple all-sky imagers (ASI), meteorological and solar irradiance measurements. The network provides high temporal and spatial resolution data for meteorological and especially solar energy related applications. With increasing photovoltaic (PV) capacity in electrical grids fluctuations in solar irradiance due to changing cloud cover may have adverse effects on the grid stability. Within Eye2Sky, new technologies and methodologies facing the demand for more accurate solar irradiance forecasts are being developed. The ASIs used in Eye2Sky record 180° field of view hemispherical sky images from fish-eye lensed cameras. Accompanied with local measurements of solar irradiance components (global, direct and diffuse) a very short-term forecast of the solar resource is possible. These nowcasts provide minutely updated information up to 20 minutes ahead with 1-minute temporal and 50 m x 50 m spatial resolution. This approach shows more precise forecasting results for the next minutes ahead compared to traditional and less detailed methods based on satellite or numerical weather prediction models. In the network, multiple ASIs are used to enlarge the spatial coverage and the forecast horizon requested by many applications. Moreover, the forecast error can be reduced with a network of cameras. In this article, the Eye2Sky network, its research results and applications are introduced

The enhancement of solar power system implementation in bheuu building

In Malaysia, the installation of PV panels in residential, industrial and commercial buildings has been imposed since 2001. This is due to the 8th Malaysia Plan (2001-2005) when Government introduced Malaysia Building Integrated Photovoltaic Technology Application (MBIPV) plan to encourage the application of renewable energy source in Malaysia. One of the alternatives that have been done by the Ministry of Energy, Green Technology and Water (KeTTHA) was installing PV panels in government buildings in Putrajaya. Mostly, the installed PV panels only cover up to 30% of the energy demand in one level of a building. However, after operating for some years, the performance of the PV panels was degrading. Since the maintenance cost for PV system is quite high, and due to the factor of lack of knowledge on how to maintain the system, the installed PV systems are mostly abandoned now. The project was discontinued after the warranty period and the contract with the contractor end. Therefore, the aim of this study is to re-improvise the abandoned PV system in one of them which is Building of Section of Legal Affairs (BHEUU). Through this study, three new models of the BIPV system were proposed, namely Model 1 (4IWOB), Model 2 (4IWB), Model 3 (1IWOB), and Model 4 (1IWB). In this study, the technical and economic assessment has been performed. From the findings, results show that Model 3 (1IWOB) provides the best choice to replace the existing BIPV system where this model only use 1 unit of inverter and no battery storage is used. Saving can be saved up to 37.5% if Model 3 (1IWOB) is chosen to replace the existing PV system at BHEUU building, where the existing system is represented by Model 1 (4IWOB), which used 4 inverters, and no battery was installed

Battery-Less Short-Term Smoothing of Photovoltaic Generation Using Sky Camera

IEEE There is a growing concern over addressing the adverse effects of variations in the output power of distributed generators such as photovoltaic generation (PVG) systems that continue to be widely introduced into power networks. Nowadays, most network operators are requiring these intermittent energy resources to seek compliance with new regulations pertaining to the restriction of their export power fluctuations. This paper aims to investigate the smoothing of the export power fluctuations primarily attributed to clouds passing over the PVG plant which are traditionally compensated by integrating battery storage (BS) system. The idea of incorporating short-term solar prediction information into the conventional smoothing approach is examined to indicate how it affects the engagement of BS in the smoothing process. Afterwards, an enhanced solar forecasting scheme based on whole-sky imaging is proposed and its performance is demonstrated through several real-time experiments complemented with simulation studies. The results reveal that the proposed PVG smoothing strategy is capable of successfully filtering rapid export power fluctuations to an acceptable extent and the conventional generation reserves will experience a negligible amount of remaining undesired power variation. This clearly bears out the hypothesis of battery-less PVG regulation

Reducing the Impact of Irradiance Ramps on PV Power Production – A Techno-Economic Analysis of Nowcasting

Electricity grids experience an increasing amount of volatile renewable energy integration. This introduces new challenges for the stable operation of the grid and the matching of supply and demand. One of the technical challenges relates to unforeseen short-term power ramps being transmitted to the electrical grids. Such ramps in power production can disrupt grid stability, leading to imbalances, fluctuations in frequency and voltage, potential equipment failures and power outages. Furthermore, they can affect electricity market dynamics, causing price fluctuations. For photovoltaic (PV) power plants the primary source of short-term variability are irradiance ramps caused by clouds. All-sky imagers offer the potential to analyse the current sky conditions and produce shortest-term forecasts (nowcasts) of the irradiance up to 20 minutes into the future. This work investigates the potential of nowcasts for mitigating power ramps through preventive curtailment and analyses the associated economic consequences. For this purpose, irradiance nowcasts for a time frame of one year are fed into a virtual PV plant model located in southern Spain. The model simulates the power output of the plant and thereby processes the irradiance nowcasts into power nowcasts. Several ramp mitigation strategies based on the power nowcasts are developed and assessed. These nowcasting strategies are benchmarked against battery storage strategies, as well as hybrid strategies combining nowcasting and battery storage. The economic performance of the configurations is analysed and compared. For this, an incentive for power smoothing in the form of a monetary penalty for missed ramps is introduced. A simplified simulation of the marketing of the produced electricity determines yearly profits for every configuration which are then used in combination with the overall system costs to calculate the net present values. Using the net present value as a benchmark, a hybrid configuration is found to be the optimal solution for the power control under the applied regulatory framework. It is able to reduce the number of ramps by 93 % while reducing the required battery size by 40 % in comparison to a standalone storage solution. However, the analysis also shows that the introduction of ramp rate regulation and the consequent investment in ramp mitigation and curtailment of energy leads to overall higher levelized costs of energy and lower net present values