The illumination angle dependency of CPV solar cell electrical performance

Influence of laterally split spectral illumination on multi-junction CPV solar cell performance

Partially shaded III-V concentrator solar cell performance

We describe a process for increasing power efficiency of concentrator photovoltaic systems by optimizing the lens-to-cell spacing. We find that there is an optimum defocus position with improved power output and reduced sensitivity to pointing errors, which in combination can result in a more than 10% enhancement. The improvement can be realized by minor changes to module cases which should not require changes to other manufacturing, installation, or component costs. In fact optimizing the defocus position allows for lower costs per unit power due to increased power and relaxed system tolerances. The paper focuses on detailed data illuminating the behavior of ultra high concentration photovoltaic modules. While one can look forward to optimizing defocus through sufficiently detailed simulation, at present, we find that an empirical determination of optimum defocus is necessary. The data reveals that even without design parameters changing, supply chain changes can have a significant impact on the optimum defocus - data from five different module configurations with components from different manufacturing lots are presented. These different configurations serve to illustrate the consequences of component changes and the importance of verifying the optimum defocus. A discussion of the effects that are important to determining the optimum defocus and which underlie these differences is included.

http://ieeexplore.ieee.org/iel7/5503869/6991619/06955707.pdf

Optimizing Defocus to Increase Efficiency in Concentrator Photovoltaic Modules

Optimizing defocus to increase efficiency in concentrator photovoltaic modules

At high solar concentration, subtle optical and electrical effects in combination can have a substantial impact on photovoltaic power (PV) generation. We have identified such an effect through its clear signature: a “ripple” in the output current with respect to the pointing angle of the concentrated PV (CPV) system to sun direction. At small angular misalignment, this effect can lower cell current by as much as 15% at 1600x concentration in full sun. At medium concentration between 500 and 1000x, while not as clearly visible in single cells, the effect also reduces output by a smaller amount. The disappearance of the “ripple” signature at low concentrations below 300x indicates that the effect is not a linear effect, such as a light loss. We attribute the pronounced angular sensitivity of power output at high concentrations to a combination of inhomogeneous spectral irradiation incident on the multijunction solar cell and of the impact of the finite lateral resistance of the cell.

Dhiren Patel

Papers

High-Concentration Photovoltaics—Effect of Inhomogeneous Spectral Irradiation