Types of solar cell/Generations of solar cells. First generation solar cells (crystalline Si, GaAs, Polycrystalline silicon solar cells). Second generation solar cells (Thin film solar cells – amorphous Si, microcrystalline Si, CdTe, CuInSe₂, Cu(InGa)Se₂, Cu2ZnSnS₄). Third generation solar cells (Nanocrystalline-based solar cells, polymer-based solar cells, dye-sensitised solar cells, concentrator solar cells, Tandem solar cells). Fourth generation solar cells (Hybrid or organic-inorganic solar cells). Next generation solar cells (Graded bandgap solar cells, Perovskite-based solar cells, Quantum dot solar cells, intermediate band solar cells, solar cells with up & down conversion, nano-structured solar cells e.g. with carbon nanotubes, grapheme etc.). Differences between solar cells, modules and panels (sizes and Efficiencies). Application of solar cell/modules/panels. Very low power application (such as in wrist watches, mobile phone, small torchlight etc, radios etc). Medium power application (such as in solar-operated cars, Street lighting, water pumping, household appliances etc). High Power and very high-power applications (as in stand-alone and grid-tied solar power plants). PV Economics: Cost of production, Cost of PV energy/Payback time, Feed-in tariff, Levelized cost etc