There are no quick fixes to long-term energy challenges. To find solutions, governments and industry benefit from sharing resources and accelerating results. For this reason the IEA enables independent groups of experts - the Energy Technology Initiatives, or ETIs1.
Solar heating and cooling (SHC) technologies can be used for a wide range of applications, from residential domestic hot water and space heating and cooling to industrial and agricultural processes. Combined with energy storage, SHC technologies can provide continuous energy supply. Policies and measures to support deployment of SHC technologies include fiscal incentives such as feed-in tariffs, renewable portfolio standards for commercial heat and subsidies, or consumer tax incentives. Regulatory approaches such as solar obligations or building regulations are also effective. Training for trade and building professionals and consumer awareness campaigns should also be considered.
The aims of the ETI focusing on solar heating and cooling (SHC) are to overcome barriers and increase the solar global market share through research, development and testing of hardware, materials and design tools; expand the solar thermal market; and raise awareness of policy makers and consumers. There are currently 21 Contracting Parties, including China, Mexico, Singapore and South Africa, and one Sponsor.
Knowledge of solar energy resources is critical when designing, building and operating successful solar systems. High penetration of electricity from solar technologies will require more precise forecasting techniques to meet fluctuations in both weather and demand.
For these reasons the SHC project, Solar Resource Assessment and Forecasting, aims to improve validation procedures of existing solar resource data so as to gain a clearer understanding of the accuracy of various methods that forecast solar radiation from a few minutes to three days in advance. Preliminary results from the project show that for forecasts of less than one hour, critical for system operators seeking to match varying supply with varying demand, application of Total Sky Imagers or all sky cameras appears promising as they provide images of how the radiation will change over the next several minutes. Participants also investigated the reliability of forecasts derived from cloud motion vectors (CMV), based on a time series of cloud images from satellite observations.
Results show that the CMV model is most suitable for up to four-hour forecasts, while numerical weather prediction (NWP) models are more accurate for four- to six-hour forecasts.
However, synthesising results from a combination of both CMV and NWP models were found to be more accurate, whether over single sites or large regions. Another method consists of combining satellite images of cloud and radiation fields with wind fields from the weather research and forecasting (WRF) model. This was found to achieve optimum forecasting results compared to real weather conditions up to six hours in advance. The results provide best practices on solar energy resources to assist policymakers and project developers in advancing solar energy integration worldwide.
* Source of the graph: Prediction of Solar Irradiance and Photovoltaic Power in Comprehensive Renewable Energy, Volume 1, pp239 - 292. DOI: 10.1002/pip.1224.
For more information: www.iea-shc.org
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