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Solar generation and wind power characteristics

Short answer

Solar electricity is generated by PV cells (silicon p-n junction produces DC, modules/arrays with inverters for AC). Wind turbine efficiency is limited by Betz limit (59.3%), practical 35-45%; energy cost is mainly capital, no fuel; capacity ranges from small to multi-MW; annual output E = P_rated × 8760 × CF, CF 20-40%, strongly dependent on wind speed.

Explain how the electricity can be generated from solar with suitable sketch. Explain the characteristics of wind power on the basis of turbine efficiency, energy cost, capacity and annual energy output.

Electricity generation from solar

Solar energy is converted mainly by photovoltaic (PV) cells. A PV cell is a silicon p–n junction; sunlight creates electron–hole pairs, which the junction field separates, producing DC voltage (about 0.5–0.6 V per cell). Cells form modules and arrays.

 Sun -> PV array -> MPPT/charge ctrl -> Battery
                         |
                     Inverter -> AC loads / grid
  • Off-grid systems store energy in batteries.
  • Grid-tied systems feed AC directly to the grid through an inverter.
  • Solar thermal plants use mirrors to make steam for a turbine (less common).

Characteristics of wind power

BasisCharacteristic
Turbine efficiencyCpC_p cannot exceed 59.3% (Betz limit); practical modern turbines 35–45%; overall wind-to-wire about 30–40%
Energy costNo fuel cost; cost is mainly capital (turbine, tower, foundation, grid). Large onshore wind is among the cheapest new sources; small turbines cost much more per kWh
CapacityFrom a few hundred watts (small) to 3–15 MW per modern unit; output ∝v3\propto v^3, so capacity rating is at rated wind speed (about 12–15 m/s)
Annual energy outputDepends on wind speed distribution; capacity factor typically 20–40%, so E=Prated×8760×CFE = P_{rated}\times 8760 \times CF
  • Since P=12ρAv3CpP = \frac{1}{2}\rho A v^3 C_p, a site with 10% higher mean wind speed gives about 33% more energy, so site selection is critical.
  • Output is variable and must be backed by storage, hydro or other plants.

✓ Answer checked by Claude Opus 5.5 (high effort)

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