Shading and available energy in a parabolic trough concentrator field

Shadow cast by one collector row on its adjacent one in a solar collector field affects the energy collection. Due to continuous change in sun’s position, shadow and its effect on adjacent row also change with time. For any orientation of collector field, extent of shading depends upon the gap between the rows. It is necessary to have enough gap between the rows to avoid shading for maximum time of the day resulting in the highest energy collection. However, the availability of open land puts constraints on the gap. The present work aims at finding the energy available for a collector field for any pitch, any orientation and any latitude considering shading. A factor called annual energy availability factor has been defined to quantify the annual energy availability at the aperture of a collector field. It is found that this factor increases significantly with increase in pitch initially and later saturates with no substantial improvement in energy collection. Performances of collector field for different orientations have also been compared. It is found that N–S mounted collector field is the best in terms of energy availability considering shading. This orientation also leads to the least cost of electricity generation. From this work, one can predict the energy availability and cost of energy production for any location, orientation and pitch. One can also choose the minimum pitch required to meet a particular energy availability requirement for given location and orientation.

► General methodology for estimating shading and energy availability in a PTC field.
► Effects of orientation, pitch, collector geometry and latitude investigated.
► Shading is maximum for North–South mounted field and minimum for East–West.
► Energy availability is maximum for North–South mounted field.
► North–South orientation of field leads to minimum cost of electricity.