Super-Multi-Junction Solar Cells—Device Configuration with the Potential for More Than 50% Annual Energy Conversion Efficiency (Non-Concentration)

Abstract

The highest-efficiency solar cell in the efficiency race does not always give the best annual energy yield in real world solar conditions because the spectrum is always changing. The study of radiative coupling of concentrator solar cells implies that efficiency could increase by recycling the radiative recombination generated by the surplus current in the upper junction. Such a configuration is called a super-multi-junction cell. We expand the model in the concentrator solar cell to a non-concentrating installation. It is shown that this super-multi-junction cell configuration is robust and can keep maximum potential efficiency (50% in realistic spectrum fluctuation) for up to 10 junctions. The super-multi-junction cell is also robust in the bandgap engineering of each junction. Therefore, a future multi-junction may not be required for tuning the bandgap to match the standard solar spectrum, as well as relying upon artificial technologies such as epitaxial lift-off (ELO), wafer-bonding, mechanical-stacking, and reverse-growth, but merely uses upright and lattice-matching growth technologies. We present two challenging techniques; one is the optical cap layer that may be the directional photon coupling layer in the application of the photonics technologies, and another is the high-quality epitaxial growth with almost 100% radiative efficiency.

Measurement and Modeling of 3D Solar Irradiance for Vehicle-Integrated Photovoltaic

“…For example, a detailed spectrum energy model for the tandem solar cell was developed at the University of Miyazaki and recently published [34]. The model, as mentioned above, was expanded to the design of the future high-efficiency solar cell for VIPV application in the worst-case combination of atmospheric parameters [35] and realistic atmospheric parameters and measured spectrum [36]. The atmospheric parameters that impact performance of high-efficiency solar cells are identified using a statistical approach [37] and also to concentrator photovoltaic (CPV) [38] that is recently considered as a right candidate [39], fine-tuning of the bandgap design for VIPV application based-on the model as mentioned above [40], prediction of the energy yield with consideration of the spectrum and angular issues [41], and the rating method of the VIPV with consideration of above issues [42].…”

Accurate Output Forecasting Method for Various Photovoltaic Modules Considering Incident Angle and Spectral Change Owing to Atmospheric Parameters and Cloud Conditions

“…where min and mean are the arithmetic minimum function and mean function. The FF was modeled by simple parabolic approximation from the degree of current mismatch between the sub-cells [36], shown in Equation (15),…”

Measurement and Modeling of the 3-D Solar Irradiance for Vehicle-Integrated Photovoltaic

“…The angular distribution model is crucial both to the validation of the 3-D solar irradiance model around the car-body and optimization design of the high-performance static concentrator module on the car-roof [28][29][30][31][32][33]. In case that the high-efficiency multi-junction cells are used for VIPV, it is essential to consider the spectrum impact, correctly, the cross effect between spectrum and angular distribution of the solar irradiance [34][35][36][37][38][39][40][41][42]. The angular distribution model is also useful for this purpose.…”

“…This curve correction factor is convenient because it can be uniquely determined for each curved surface given the incidence angle characteristics of the module and the incidence angle distribution of the solar cell if the mismatching loss is neglected. The curve correction factor can be calculated by numerical, geometric calculation [35] or raytracing simulation [1,[16][17][18][19][20]46]. For the geometrical calculation, it is important to add two conditions for avoiding complexity.…”