Improved quality control procedures and models for solar radiation using a world-wide database.

Engineering notes

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Chinese explanation / 中文解读

中文解读待补充：本站会优先为光伏效率、钙钛矿太阳能电池、储能技术、太阳能热利用、BIPV、并网技术等高价值论文补充中文说明。

Original abstract

This thesis deals with various aspects of broadband horizontal solar irradiance. Quality control of measured datasets is identified and analysed. It was found that solar irradiance datasets may contain significant errors. These sources of errors were divided into two categories: inherent instrument errors and operation-related errors. Methods of assessing the quality of the datasets were evaluated and found to be unsatisfactory. A new method was therefore developed to quality control solar irradiance data. The quality control procedure consists of two tiers of tests. The first tests are physical tests that identify and remove data points that are physical impossibilities. The second tier consists of the creation of a mathematical envelope of acceptance in a sky clarity index domain. This envelope is based on multiples of standard deviations of the weighted mean of clearness index to diffuse ratio. The datasets used in this study were thus quality controlled to remove obvious outliers. Modelling the solar resource is an important tool for engineers and scientists. Such models have been developed since the second half of the 20th century. Some models rely on one or two meteorological parameters to estimate solar irradiance, while others are more complex and require a far greater number of inputs. Two of these models have been analysed and evaluated. Both are all-sky, broadband solar irradiance models. The first model analysed is the Meteorological Radiation Model (MRM). This model is essentially sunshine-based, with atmospheric turbidity also considered. The beam irradiance component was found to be acceptable given the number of inputs required. Additional parameters would increase complexity without noticeable improvement. The regressions were modified to account for sunshine fraction banding. However, the diffuse irradiance component was identified as having potential for improvement. Accordingly, an enhanced model was developed. This new model was found to be superior to the original, and was named the Improved Meteorological Radiation Model (IMRM). The second type of model investigated is the cloud-based radiation model. This model is simple to use and relies on regressions between irradiation, solar altitude angle, and cloud cover. Analysis of cloud distribution revealed shortcomings in existing regressions. New regressions were therefore developed, resulting in a model superior to its predecessors. Clear-sky modelling is important for maximum load calculations; however, accurate extraction of clear-sky broadband data remains challenging. Existing clear-sky identification techniques were evaluated, and a new method was devised. The resulting datasets were applied to four clear-sky models: the MRM, Page’s Radiation Model (PRM), Yang’s radiation model, and Gueymard’s REST2 model. It was found that using this new method of extracting extreme clear-sky data improved model performance compared to using quasi-clear-sky data. Solar radiation modelling is not an end in itself; it must serve practical engineering applications. Napier University installed a 160 m² photovoltaic facility in 2003. A 27-year solar radiation dataset for Edinburgh was available for feasibility analysis, but contained data gaps. The cloud radiation model developed in this study was used to address this issue. Additionally, a full life-cycle analysis of the project was conducted. It was found that, with an average efficiency of around 12%, the facility would repay its embodied energy in eight years, and, based on conservative energy price forecasts, the financial payback period is under 100 years.

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