Introduction

The previous discussion was principally intended to address the most common class of photovoltaic solar power technology, namely the flat-panel system. Another important solar power technology is the concentrated photovoltaic (CPV) system. Systems in this class of technology are designed to convert solar energy into electrical energy through special photovoltaic solar cell designs, which use concentrating lenses to concentrate and focus solar rays on multilayer or multijunction solar cells. To achieve maximum efficiency, the assembly of cells forming a photovoltaic module or panel is secured on dual-axis trackers that track the rise and fall of the sun from sunrise to sunset. Efficiencies obtained from CPV are 25% to 50% higher than those of flat-panel technologies. Even though the CPV technologies are capable of producing significantly higher energy production, problems with specific system configurations, as well as economic considerations, have limited their deployment to specific geographic locations. This segment covers specifics of CPV technologies, both pros and cons.

Researchers in the field of photovoltaics have always been faced with the problem of how they can increase the efficiency of this photovoltaic conversion process while reducing cost significantly. The solution for attaining this goal has been reached with concentrator photovoltaics (CPV) technologies, where the cost reduction has been achieved by replacing expensive PV cell material with lower-cost optical systems that enable a larger photovoltaic receiver aperture.

Current installed power generation capacity throughout the world is 2 terawatts (TW). Because of the growth in energy consumption and replacement of aging power plants, it is estimated that as much as 6 TW of capacity will be required by 2030.

Relying primarily on fossil fuels to meet this increased demand will have severe impacts on the environment and natural resource reserves, so alternative sources must be implemented. Solar power is the most abundant renewable in the world. Every hour, enough solar energy hits the Earth to meet the current world demand for one year. In essence, we have free fuel for life at our disposal; it just has to be harvested. Of the various solar technologies available, concentrated photovoltaic technology is increasingly being recognized as holding the greatest promise to meet the energy challenges facing the world.

Multijunction Photovoltaic Cells

Multijunction solar cells were first developed and deployed for satellite power applications, where the high cost was offset by the weight reduction and increase in performance efficiency.