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Energy conversion efficiency of various technologies which utilize renewable energy sources is still small except hydropower (Sahli et al. 2018). Advances are taking place worldwide to increase the efficiency. Since, solar and wind sectors are expanding at much larger scale compared with other energy sources. These two are further discussed with respect to efficiency increment.

In solar industry, scientific community is evaluating various new materials to produce electricity more efficiently. Thin‐film solar cells are cheaper in cost and flexible in nature; however, efficiency of these cells is still a matter of concern for researchers so experimental studies are carried out on the range of materials such as amorphous silicon, CdS/CdTe and CIS to overcome this barrier (El Chaar et al. 2011). To improve the efficiency of organic and polymer solar cells, use of a controlled layer of multi‐wall carbon nanotubes is also reported (Capasso et al. 2014) which improves the efficiency of these cells from 8 to 10%. DSSCs also fall in the same category of low efficiency which is again between 8 and 12%. To increase the efficiency of PV system, generated current is transferred to grid systems. This grid is either mounted on ground or built on the roof of a building so that PV system provides better efficiency as it mainly depends on the intensity of solar radiation. On an average, capacity of PV panel ranges from 10 to 60 MW. Lifetime of a well‐developed PV panel is approximately 10 years at 90% capacity, and it increases to 25 years with a 10% decrease in capacity (Devabhaktuni et al. 2013).

A major challenge in CPV system is reduction in efficiency of PV due to increase in temperature while concentrating light as conversion efficiency of CPV is still small. Remaining solar radiation gets converted into thermal energy which raises the temperature of junction in the cell, thereby decreasing efficiency. Lifetime of PV also decreases due to increase in temperature. This leads to overall degradation in performance of PV system (Pandey et al. 2016). So, more studies are required to explore ways to decrease temperature of the CPV system.

In wind energy sector, replacement of components of wind turbine system with latest components having cost‐effective technology will increase the efficiency of the existing wind farm. In addition to this, repowering of onshore wind assets can enhance operating lifetime of the current wind project. Repowering can be either full or it can be partial.