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Relevance: GS-III (Infrastructure & Energy) | Source: The Indian Express
The Context: Sri Lanka’s national power grid recently collapsed, leaving 23 million people without electricity for hours. The unexpected trigger behind the blackout was thousands of rooftop solar systems shutting themselves off at the exact same moment. As India rapidly adds millions of rooftop solar panels under the PM Surya Ghar Yojana, this incident is an important wake-up call on how to keep the national power grid stable.
1. How Rooftop Solar Can Crash a National Grid
- The Trigger: On a sunny afternoon, rooftop solar was supplying nearly half of Sri Lanka’s electricity (~2,499 MW). When a major thermal power plant suffered a sudden glitch, the grid’s voltage and frequency (normally kept steady at 50 Hz) dipped for a fraction of a second.
- The Inverter Safety Reflex: Solar panels make Direct Current (DC) electricity, which a box called an inverter converts into Alternating Current (AC) for homes and the grid. To protect equipment and utility workers (a safety feature called anti-islanding), inverters are programmed to disconnect automatically if they sense abnormal grid voltage.
- The Domino Effect: Because most rooftop inverters were set too sensitively, the minor grid wobble caused thousands of them to trip off all at once. Instantly losing half its power supply overwhelmed traditional coal and hydro plants, shutting down the entire country’s grid.
2. Key Grid Concepts Simplified for UPSC
- Non-Dispatchable Power & Low Grid Inertia: Unlike coal, gas, or hydro plants—which have heavy spinning turbines that naturally absorb shocks (grid inertia) and can be turned up or down on demand (dispatchable)—solar power depends entirely on sunlight and offers zero natural inertia to cushion sudden frequency drops.
- Low-Voltage Ride-Through (LVRT): A smart technical feature (mandated in India by the Central Electricity Authority) that trains solar inverters to “ride through” brief voltage dips of a few seconds and stay connected, rather than panicking and disconnecting at the first sign of trouble.
Practice MCQ
Q. Consider the following statements regarding rooftop solar integration and electricity grid stability:
- Standalone rooftop solar power is classified as a “dispatchable” generation source because grid operators can manually ramp its output up or down to match real-time demand.
- Low-Voltage Ride-Through (LVRT) capability allows solar inverters to remain connected to the main grid during brief voltage dips, preventing cascading power blackouts.
Which of the statements given above is/are correct?
(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Answer: (b) 2 only
Explanation: Statement 1 is incorrect because solar and wind energy (without battery storage) are non-dispatchable and intermittent—their generation depends on weather and sunlight rather than operator control. Statement 2 is correct; LVRT ensures that solar inverters withstand temporary voltage drops instead of tripping offline all at once and crashing the grid.
Explanation: Statement 1 is incorrect because solar and wind energy (without battery storage) are non-dispatchable and intermittent—their generation depends on weather and sunlight rather than operator control. Statement 2 is correct; LVRT ensures that solar inverters withstand temporary voltage drops instead of tripping offline all at once and crashing the grid.
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