--- title: "Energy sources and solar power generation" subject: "Power Plant Design" chapter: 1 key: "semester_8/power_plant_design:energy-sources-solar-power" source: https://www.bctengineer.com/q/semester_8/power_plant_design/energy-sources-solar-power site: BCT Engineering --- # Energy sources and solar power generation Power Plant Design · Chapter 1: Energy Sources and Electric Power Generation - Asked in: 2072 Magh, 8 marks - Video: [How do solar panels work? - Richard Komp](https://www.youtube.com/watch?v=xKxrkht7CpY) — TED-Ed - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/energy-sources-solar-power - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-1 ## Question What are the conventional and non-conventional energy sources? Describe with suitable sketches how electric power can be obtained from solar? ## Short answer Conventional sources (coal, oil, gas, large hydro, nuclear, traditional biomass) are exhaustible and polluting; non-conventional (solar, wind, micro hydro, biogas, geothermal) are mostly renewable and clean. Solar electricity is generated by PV cells (p-n junction converts sunlight to DC, modules/arrays with inverters) or solar thermal (mirrors concentrate sunlight to produce steam for a turbine). ## Answer #### Conventional and non-conventional energy sources | Conventional | Non-conventional | |---|---| | Coal, oil, natural gas | Solar (PV and thermal) | | Large hydropower | Wind | | Nuclear | Micro/small hydro | | Traditional biomass (firewood, dung) | Biogas, modern biomass | | | Geothermal, tidal, wave, hydrogen | Conventional sources are long established, mostly exhaustible and polluting; non-conventional sources are mostly renewable, clean and still developing. #### Electric power from solar energy Solar energy is converted to electricity in two ways. **1. Solar photovoltaic (PV) – direct conversion** A PV cell is a p–n junction of silicon. Photons with energy greater than the band gap (about 1.1 eV for Si) create electron–hole pairs. The junction field separates them and a DC voltage (about 0.5–0.6 V per cell) appears. Cells are connected in series and parallel to form modules and arrays. ```text Sunlight || vv +------+ +-----------+ +---------+ | PV |---->| Charge |--->| Battery | |array | DC | ctrl/MPPT | +---------+ +------+ +-----------+ | | | v v +---------+ DC loads |Inverter |--> AC load / grid +---------+ ``` - **Off-grid (stand-alone)**: PV + charge controller + battery + inverter. - **Grid-tied**: PV + MPPT inverter feeding directly to grid (no battery). - Module efficiency about 15–22%. **2. Solar thermal power – indirect conversion** Mirrors concentrate sunlight to heat a fluid, which makes steam to drive a turbine–generator. ```text Sun --> Concentrator (trough/dish/tower) | Hot fluid --> Heat exchanger --> Steam | Turbine --> Generator | Condenser ``` Types: parabolic trough, central receiver (power tower), parabolic dish (Stirling engine). Thermal storage (molten salt) allows output after sunset. #### Solar in Nepal Nepal receives about 4.5–5.5 kWh/m²/day with around 300 sunny days a year, so PV is used in solar home systems, solar pumps and grid-connected plants of several MW. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How does a PV cell produce voltage? A. Photons above the band gap create electron-hole pairs separated by the junction field B. Heat expands the silicon C. Wind rotates it D. Water flows over it Answer: A. A p-n junction gives about 0.5-0.6 V DC per cell. (Key point: PV principle) 2. Which system has no battery? A. Off-grid B. Grid-tied with MPPT inverter C. Stand-alone D. Solar home system Answer: B. Grid-tied feeds AC directly to the grid; off-grid needs battery and charge controller. (Key point: Off-grid vs grid-tied) 3. In solar thermal power, sunlight is used to A. Create electron-hole pairs B. Charge batteries directly C. Concentrate heat to make steam for a turbine-generator D. Drive a wind rotor Answer: C. Mirrors heat a fluid that makes steam; molten salt storage allows output after sunset. (Key point: Solar thermal) ## Related in Power Plant Design - [Conventional, non-conventional sources and biomass](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aenergy-sources-biomass) — Power Plant Design, chapter 1 - [Replacing fossil fuel with non-conventional energy](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aenergy-sources-replace-fossil) — Power Plant Design, chapter 1 - [Solar generation and wind power characteristics](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Asolar-generation-wind-characteristics) — Power Plant Design, chapter 1 - [Energy sources in Nepal and wind scope](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aenergy-sources-nepal-wind) — Power Plant Design, chapter 1, asked 2× - [Captive power generation and its needs](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Acaptive-power-generation) — Power Plant Design, chapter 1, asked 3× - [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 ## Related in other subjects - [Conventional vs non-conventional sources with schematic](https://www.bctengineer.com/question.md?key=semester_4%2Fpower_system_analysis_i%3Aconventional-vs-nonconventional-sources-schematic) — Power System Analysis I, chapter 1 - [Conventional and non-conventional sources](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Aconventional-nonconventional-sources) — Energy Environment and Society, chapter 2 - [Conventional vs renewable energy for generation](https://www.bctengineer.com/question.md?key=semester_4%2Fpower_system_analysis_i%3Aconventional-vs-renewable-generation) — Power System Analysis I, chapter 1, asked 2× - [Conventional sources and features of a station](https://www.bctengineer.com/question.md?key=semester_4%2Fpower_system_analysis_i%3Aconventional-sources-features) — Power System Analysis I, chapter 1