Jawaharlal Nehru Technological University Hyderabad B.Tech III NON-CONVENTIONAL ENERGY SOURCES Previous Question Paper (January/February - 2021 - R16)

The assessment of non-conventional energy sources involves evaluating their technical, economic, environmental, and social viability to determine their suitability for large-scale integration. The primary criteria are as follows:

• Resource Availability and Reliability: The fundamental criterion is the spatial and temporal distribution of the energy source. For solar and wind, this involves long-term meteorological data analysis to determine capacity factors. Reliability is assessed through the consistency of the resource and the ability to predict output fluctuations.
• Technical Feasibility and Efficiency: This evaluates the maturity of the conversion technology, such as photovoltaic cell efficiency or wind turbine aerodynamic performance. It includes the compatibility of the energy source with existing grid infrastructure and the necessity for energy storage systems to manage intermittency.
• Economic Viability: Assessment is based on the Levelized Cost of Energy (LCOE), which accounts for capital expenditure (CAPEX), operational and maintenance costs (OPEX), and the project lifespan. It also considers the payback period, internal rate of return, and the impact of government subsidies or carbon credits.
• Environmental Impact: This criterion measures the lifecycle emissions of the technology, including manufacturing, installation, operation, and decommissioning. It also considers land use requirements, impact on local biodiversity, noise pollution, and water consumption during the energy conversion process.
• Social and Policy Acceptance: The potential is influenced by public perception, local community displacement, and the alignment with national energy policies. Regulatory frameworks, such as feed-in tariffs and renewable energy certificates, significantly impact the deployment potential.
• Geographical and Infrastructure Constraints: Proximity to load centers (transmission distance) and the availability of existing grid connectivity are critical. Remote locations may require decentralized or micro-grid solutions, which alter the cost-benefit analysis.

A solar cell, or photovoltaic cell, is an electronic device that converts the energy of sunlight directly into electricity through the photovoltaic effect. It is typically constructed from semiconductor materials, most commonly silicon, which are doped to create a p-n junction.

The principle of operation is based on the interaction of photons with the semiconductor material:

1. Photon Absorption: When sunlight strikes the solar cell, photons with energy greater than the bandgap of the semiconductor material are absorbed. This energy is transferred to electrons in the valence band, exciting them to the conduction band and creating electron-hole pairs.
2. Charge Separation: The p-n junction creates an internal electric field at the interface between the p-type and n-type layers. This electric field acts as a barrier that forces the photo-generated electrons to move towards the n-type side and the holes towards the p-type side.
3. Current Collection: Metal contacts on the top and bottom of the cell collect these separated charges. When an external load is connected across these contacts, a direct current (DC) flows through the circuit, providing electrical power.

The efficiency of this process depends on the material's bandgap, the intensity and spectrum of the incident light, and the minimization of recombination losses where electrons and holes recombine before being collected.