The solar industry has matured in last 40 years. The National Energy Research Lab (NERL) data published in 2014 provides a great summary of advances made in solar PV conversion cells.
As it is clear in the Figure 1 last three dacads have seen significant increase in the efficiency of the solar PV conversion, primarily because of material science research and development in mono-crystal, poly-crystal, multi-crystal, amorphous and thin film solar cells by developing PN junction from III-V and II-VI materials in the periodic table of elements. However, the dominant technology is based on Si doped with tri valent and penta valent impurities and generating indirect band-gap solar cell and GaAs (III-V) direct band-gap solar cells. The multi-junction solar cells are used to enhance the efficiency of the solar cells but their production cost is much higher than Si solar cells.
As we go towards higher efficiencies the cost of the solar cell production prohibits the grid parity which is the economic hurdle in broad use of solar PV panels. The subsidies provided by the federal energy programs is not a sustainable solution to bring the grid-parity.
The Photonic Solar Conversion (PSC) technology exploits the mass produced Si solar cells with innovative photonics to enhance efficiency and power generation by 2 to 3 times. For example, PSC can enhance efficiency of a poly Si solar cell from 12% to 24% to 30%.