The rise of non-imaging optics for rooftop solar collectors

In this paper we explore the use of non-imaging optics for rooftop solar concentrators. Specifically, we focus on compound parabolic concentrators (CPCs), which form an ideal shape for cylindrical thermal absorbers, and for linear PV cells (allowing the use of more expensive but more efficient cells). Rooftops are ideal surfaces for solar collectors as they face the sky and are generally free, unused space. Concentrating solar radiation adds thermodynamic value to thermal collectors (allowing the attainment of higher temperature) and can add efficiency to PV electricity generation. CPCs allow that concentration over the day without the need for tracking. Hence they have become ubiquitous in applications requiring low concentration.