The discussion of the energy balance of a photovoltaic system during its lifetime started at the beginning of PV systems deployment in the early 80s. The critics often argued that a photovoltaic system never produced more energy than the required to manufacture it.
2.1.2. Energy and exergy efficiencies The performance analysis of most of energy systems is based on energy analysis which accounts only energies at inlet and outlet of the system . The energy based analyses of various systems have been carried out by many researchers over the past decades.
Moreover, the exergy analysis also provides true sense of diversion of existing system from the ideal one . The solar energy can be utilized (directly or indirectly) in different applications such as solar drying, solar refrigeration and air conditioning, solar water heating, solar cooking and solar power generation.
In general, energy is a property of an object which enables it to perform work through transformation into different forms. Energy analysis can be carried out using basic laws of thermodynamics, to study the work performance of process. Energy is manifested in mainly two forms viz. macroscopic and microscopic.
The cost of the electricity generated by a PV system is determined by the capital cost (CAPEX), the discount rate, the variable costs (OPEX), the level of solar irradiation and the eficiency of the solar cells.
The production of solar electricity requires the investment of a certain amount of energy, either during the manufacturing phase of the photovoltaic systems or during the operational and end-of-life phases. The energy balance throughout the whole life cycle is a critical parameter for the evaluation of the sustainability of solar electricity.