Introduction: Concentrated Photovoltaics

Over the past several years, the PV industry has experienced record growth due to a combination of government incentives promoting investment in solar projects and aggressive cost reduction by manufacturers leveraging the increased production volumes. Unfortunately, as a result of the current macroeconomic climate, many of these investment incentives have ended or are on a schedule to do so. In addition, fierce price competition, resulting from an overcapacity situation in specifically the C-Si flat plate market, has driven cost expectations below sustainable levels for many manufacturers. Nevertheless, the demand for solar energy continues to be strong and particularly the interest in large, utility-scale projects is on the rise.

To address the growing need for low-cost, low-impact, utility-scale solar power, developers are increasingly turning to concentrating photovoltaics as a viable means for further reducing the cost of energy produced, aka the levelized cost of energy (LCOE). By utilizing concentration, module manufacturers are able to increase the power output of their systems, by a factor greater than the system cost impact associated with enabling the concentration, thereby effectively decreasing the LCOE.

High-concentration PV systems, operating with high-efficiency (39-40 percent) multi-junction solar cells and concentrations of >200x (typically 500-1000x), have garnered much of the attention to date. However, within the past one to two years, there have also been a number of meaningful product and project announcements based on low-concentration PV, operating in the 2-10x concentration range, as well as medium concentration PV, operating in the 10-200x concentration range. Both of these approaches are based on the use of lower-efficiency, but also lower-cost, standard C-Si solar cells that, when combined with concentration, also have the potential to drive a reduction in the LCOE.

Aside from thermal management, one of the keys to allowing standard C-Si solar cells to operate under concentration is enabling the cell to handle the increased current generated. One method for addressing this requirement is the use of laser-grooved buried contacts (LGBC), which provide for a larger front-side contact without an increase in the shadowing on the PV surface. The manufacture of LCBGs requires advanced metrology tools and techniques to make sure the process is optimized and well controlled.

The following article details work by researchers at Loughborough University demonstrating a novel technique for using coherence correlation interferometry to provide a full 3D surface analysis of the laser grooves in which the LGBCs will be created to facilitate and control optimization of the laser ablation process.

FPV6_Intro_CPV.pdf