--- title: "Thermal, wind and PV plants compared" subject: "Power Plant Design" chapter: 1 key: "semester_8/power_plant_design:thermal-wind-pv" source: https://www.bctengineer.com/q/semester_8/power_plant_design/thermal-wind-pv site: BCT Engineering --- # Thermal, wind and PV plants compared Power Plant Design · Chapter 1: Energy Sources and Electric Power Generation - Asked in: 2071 Bhadra, 8 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/thermal-wind-pv - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-1 ## Question Compare the operational characteristics of thermal, wind and PV plant on the basis of reliability, grid connection, efficiency, operating range and maintainability. ## Short answer Thermal is firm, synchronous, 30–40% efficient, dispatchable above 40–50% load, with high fuel cost and complex maintenance. Wind is variable with 20–40% capacity factor, converter-connected, limited to cut-in/cut-out speeds, moderate maintenance. PV is intermittent with 15–20% capacity factor, inverter-connected, no inertia, low maintenance, and very low running cost. ## Answer **Thermal** plants burn fuel to make steam for a turbine; **wind** plants convert the kinetic energy of air through rotor blades and a generator; **PV** plants convert sunlight directly into electricity in semiconductor cells. #### Comparison | Basis | Thermal plant | Wind plant | Solar PV plant | |---|---|---|---| | Energy source | Coal, oil, gas | Wind (renewable) | Sunlight (renewable) | | Reliability | Firm, dispatchable; availability about 70–85% | Variable and intermittent; capacity factor about 20–40% | Daytime only, cloud dependent; capacity factor about 15–20% | | Grid connection | Synchronous generators; provide inertia and voltage control | Induction generator, DFIG or converter-connected PMSG; reactive power and fault ride-through issues | Through inverters; no inertia; harmonics, voltage rise; needs grid codes | | Efficiency | About 30–40% | About 35–45% of wind power ($C_p$ less than 0.593, Betz limit) | About 15–22% (module) | | Operating range | Stable above about 40–50% load; slow start | Generates between cut-in (about 3–4 m/s) and cut-out (about 25 m/s); rated output at about 12–15 m/s | From very low to peak irradiance; MPPT; zero at night | | Controllability | Fully dispatchable | Only curtailment and pitch control | Only curtailment | | Maintainability | Complex: boiler, turbine, fuel and ash handling, many staff | Moderate: gearbox, blades, bearings at height | Very simple: cleaning, inverter replacement | | Running cost | High (fuel) | Low | Very low | | Capital cost | Moderate | Moderate to high | Low and falling | | Emissions | High | None in operation | None in operation | | Life | 25–30 years | 20–25 years | 25 years | #### Remarks Thermal plants give reliable base load but are costly to run and polluting; wind and PV are clean with low running cost but intermittent and need storage, backup or hybrid operation. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What limits the efficiency of a wind plant to about 35-45% of wind power? A. Cp is below the Betz limit of 0.593 B. Cut-out speed C. Inverter losses only D. Cp can reach 1 but gearbox loses power Answer: A. The power coefficient Cp cannot exceed the Betz limit 0.593. (Key point: Wind efficiency limit) 2. Within which wind speeds does a wind plant generate? A. Zero to rated speed B. Between cut-in (about 3-4 m/s) and cut-out (about 25 m/s) C. Above 12-15 m/s only D. Between 10 and 40 m/s Answer: B. Generation occurs between cut-in and cut-out, with rated output at about 12-15 m/s. (Key point: Wind operating range) 3. Which is a grid issue of PV plants? A. They provide large inertia B. They use synchronous generators C. They need no grid code D. They connect through inverters with no inertia, causing harmonics and voltage rise Answer: D. PV is inverter connected, so it lacks inertia and can cause harmonics and voltage rise. (Key point: Grid connection of PV) 4. Which plant is fully dispatchable? A. Wind B. Thermal C. PV D. Both wind and PV Answer: B. Thermal can be controlled by fuel input; wind and PV only allow curtailment (and pitch control for wind). (Key point: Controllability) ## Close variants set in other exams - [Thermal, geothermal and PV plants compared](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Athermal-geothermal-pv) — Power Plant Design, chapter 1, asked 7× - [Thermal versus hydro operational characteristics](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Athermal-vs-hydro-operational) — Power Plant Design, chapter 1, asked 8× - [Thermal, geothermal and nuclear plants compared](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Athermal-geothermal-nuclear) — Power Plant Design, chapter 1, asked 7× - [Thermal, hydro and solar PV plants compared](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Athermal-hydro-solar-pv) — Power Plant Design, chapter 1, asked 8× ## Related in Power Plant Design - [Solar versus hydro operational characteristics](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Asolar-vs-hydro-economics) — Power Plant Design, chapter 1, asked 5× - [Solar PV versus hydro and their combination](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Asolar-pv-hydro-combination) — Power Plant Design, chapter 1 - [Hydropower versus solar PV in Nepal](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahydro-vs-solar-pv-nepal) — Power Plant Design, chapter 1 - [Tidal versus wind power plant](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atidal-vs-wind) — Power Plant Design, chapter 1 - [Grid-tied solar PV versus hydropower](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Agrid-tied-pv-vs-hydro) — Power Plant Design, chapter 1 - [Operational characteristics of combined cycle plant](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Accgt-operational-characteristics) — Power Plant Design, chapter 1