Solar-thermal collectors operating under real conditions rarely reach steady-state operation due to temporal fluctuations in the climate/environmental conditions and thermal loads. Figure 1 shows typical UK weather map. The incident irradiance, the ambient temperature and the wind speed can vary during the day as shown in Figures 2-4. These figures show the data collected in London at a temporal resolution of 1-minute. As a consequence of the time-varying inputs, collector models that describe dynamic behaviour are required for the accurate prediction of the thermal output and for optimising the control strategy of such systems. We develop detailed 3-D thermal sub-models that can be adapted to various geometries or collector configurations, including vacuum-tube thermal collectors, sheet-and-tube thermal and PV/T collectors
