---
title: "Solar versus hydro operational characteristics"
subject: "Power Plant Design"
chapter: 1
key: "semester_8/power_plant_design:solar-vs-hydro-economics"
source: https://www.bctengineer.com/q/semester_8/power_plant_design/solar-vs-hydro-economics
site: BCT Engineering
---

# Solar versus hydro operational characteristics

Power Plant Design · Chapter 1: Energy Sources and Electric Power Generation

- Asked in: 2079 Chaitra, 6 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/solar-vs-hydro-economics
- Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-1

## Question

Compare the operational characteristics of Solar Power plant with hydro power plant on the basis of reliability, grid connection, efficiency, operating range, maintainability and economics.

## Short answer

Solar PV is intermittent, inverter-connected, 15-22% efficient, not dispatchable, low maintenance, low and falling capital, quick to install, about 25-year life. Hydro is continuous, synchronous, 85-92% efficient, fully dispatchable, high capital, long construction, 50+ year life. Both have very low running costs; solar complements dry-season hydro.

## Answer

A **solar power plant** (mostly PV) converts sunlight directly into electricity; a **hydropower plant** converts the energy of falling water through turbines and synchronous generators.

#### Comparison
| Basis | Solar PV plant | Hydropower plant |
|---|---|---|
| Reliability | Daytime only, weather dependent; capacity factor about 15–20%; needs battery or backup | Continuous; RoR seasonal, storage firm; capacity factor about 50–65% |
| Grid connection | Via inverters; no inertia; voltage rise and harmonics; MPPT and grid codes needed | Synchronous machines; give inertia, reactive power, frequency control and black-start |
| Efficiency | About 15–22% (module), lower overall | About 85–92% |
| Operating range | Not dispatchable; follows sun; can only curtail | Fully dispatchable 0–100% through governor; good part-load (Pelton, Kaplan) |
| Maintainability | Simple; cleaning, inverter replacement; no moving parts | Mechanical and civil maintenance; sediment erosion; skilled staff |
| Economics: capital | Low and falling; modular; builds in months | High per kW; long construction (4–8 years) |
| Economics: running | Very low | Very low |
| Economics: life | About 25 years | 50+ years |
| Economics: tariff | Low energy cost in sunny areas but storage adds cost | Low cost per kWh over long life |

#### Remarks
- Hydro is more reliable, efficient and grid-friendly; solar is cheaper and quicker to install.
- In Nepal, solar is strongest in the dry season when river flows are low, so both complement each other.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Capital cost comparison:
   A. Solar is high with long construction; hydro low
   B. Solar is low and falling, built in months; hydro is high with 4-8 years
   C. Both identical
   D. Hydro built in months
   Answer: B. Hydro needs dam, tunnel and powerhouse; PV is modular. (Key point: Capital cost)

2. Typical capacity factors are
   A. Solar 50-65%, hydro 15-20%
   B. Solar 15-20%, hydro 50-65%
   C. Both 90%
   D. Both 15-20%
   Answer: B. PV works only in daylight, while hydro runs day and night. (Key point: Capacity factor)

3. Which has the longer life?
   A. Hydro, 50+ years vs solar about 25 years
   B. Solar, 50+ years
   C. Both 25 years
   D. Both 50 years
   Answer: A. Long life helps hydro's low cost per kWh. (Key point: Life)

4. Why is hydro more grid-friendly?
   A. Synchronous machines give inertia, reactive power, frequency control and black-start
   B. It uses inverters
   C. It is not dispatchable
   D. It has no inertia
   Answer: A. Solar via inverters has no inertia and needs grid-code support. (Key point: Grid support)

## Close variants set in other exams

- [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×
- [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×

## Related in Power Plant Design

- [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
- [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
- [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
- [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
- [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