--- title: "Grid-tied solar PV versus hydropower" subject: "Power Plant Design" chapter: 1 key: "semester_8/power_plant_design:grid-tied-pv-vs-hydro" source: https://www.bctengineer.com/q/semester_8/power_plant_design/grid-tied-pv-vs-hydro site: BCT Engineering --- # Grid-tied solar PV versus hydropower Power Plant Design · Chapter 1: Energy Sources and Electric Power Generation - Asked in: 2080 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/grid-tied-pv-vs-hydro - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-1 ## Question Compare grid tied solar PV with hydropower plant on the basis of availability, grid connectivity, easiness to control and investment cost. ## Short answer PV is available only during sunshine (15–20% capacity factor), connects through inverters without inertia, is non-dispatchable, and has low modular investment cost. Hydro is available day and night (50–65% capacity factor), connects synchronously with inertia and reactive support, is fully dispatchable, and has high capital cost. ## Answer A **grid-tied solar PV plant** feeds DC power from PV modules into the AC grid through inverters, without batteries. A **hydropower plant** converts water energy using turbines and synchronous generators. #### Comparison | Basis | Grid-tied solar PV | Hydropower plant | |---|---|---| | Availability | Only during sunshine (about 5–6 effective hours a day); zero at night; drops in cloudy monsoon; capacity factor about 15–20% | Day and night; seasonal for run-of-river (lower in dry season); storage plants available all year; capacity factor about 50–65% | | Grid connectivity | Through inverter with MPPT and anti-islanding; no rotating inertia; can cause voltage rise and harmonics; can be placed near loads (rooftop, distribution level) | Direct synchronous connection; provides inertia, reactive power and frequency support; usually remote, needing long transmission lines | | Easiness to control | Not dispatchable; output can only be reduced (curtailed); fast inverter control of reactive power | Fully controllable by governor and excitation; fast ramp; used for peak load and frequency regulation | | Investment cost | Low and falling per kW; modular; installation in months; simple civil works | High per kW due to dam, tunnel, penstock and powerhouse; 4–8 years construction; geological risk | | Running cost | Very low | Very low | | Life | About 25 years | 50+ years | #### Remarks - PV is cheap and fast to build but variable; hydro is costly to build but reliable and controllable. - In Nepal, grid-tied PV complements run-of-river hydro in the dry season; hydro reservoirs can balance solar variability. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Grid-tied PV availability is A. 24 hours a day B. only during sunshine (about 5-6 effective hours), zero at night C. constant D. higher than hydro in all respects Answer: B. Hydro can run day and night, so its capacity factor is higher. (Key point: Availability) 2. Which is a feature of PV grid connection? A. Direct synchronous connection B. Through an inverter with MPPT and anti-islanding, no inertia, can be placed near loads C. Provides inertia D. Needs long transmission lines always Answer: B. PV can be at distribution level, unlike remote hydro. (Key point: Connectivity) 3. Ease of control: A. PV is fully dispatchable; hydro is not B. Hydro is controllable by governor and excitation; PV output can only be curtailed C. Neither is controllable D. Both fully controllable in the same way Answer: B. Hydro ramps fast and regulates frequency. (Key point: Ease of control) 4. Why is hydro investment cost per kW high? A. Dam, tunnel, penstock and powerhouse, long construction and geological risk B. Costly fuel C. Inverters only D. Short construction Answer: A. PV has simple civil works and installs in months. 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