The photovoltaic (PV) energy conversion chain: irradiation to grid impact

The research presented in this thesis aims to enhance understanding of the influence of the inherent variability of solar irradiance on nationwide photovoltaic (PV) system performance. The spatial and temporal consistency of the solar resource is investigated. The case study area is the UK and the body of work presents nine publications written over four years with this objective in mind.The key research theme is to produce national solar resource maps from ground-based measurements of solar radiation. Geographical Information System (GIS) techniques are utilised to build a UK map of irradiation from geographically sparse data, requiring development of new tools to both generate and verify the map data. With an augmented understanding of the solar resource, PV system dispersal is then investigated, allowing analysis and prediction of the impact on the electrical grid. The papers describe: (1) determination of the most appropriate algorithm for interpolating ground-based irradiation measurements in the UK to countrywide coverage; (2) selection of solar irradiance component separation and translation models to obtain plane-of-array irradiation from the weather station global horizontal records; (3) justification of weather stations data as a fundamental model input; (4) statistical analysis of LiDAR data and application of GIS models to LiDAR data to obtain PV system tilts and azimuths as model inputs for (2); (5) conversion of solar irradiation to electrical output; (6) shading effects; (7) study of geographic divergence of generation; (8) aggregate grid variability; and (9) future installation scenarios.There has been no previous study which commences with obtaining irradiation values for PV and proceeds through the entire modelling chain to assess cumulative impacts on grid transformers. This study may be adapted as a guide when undertaking equivalent research in other countries. Specifically, the work presented here is more extensively validated than that of previous authors. A nationwide analysis of spatial and temporal variation of PV output is delivered and current and future impacts on the National Grid are taken into consideration.