Jaideep Saraswat, Nikhil Mall

India has been a global frontrunner in climate commitment, setting ambitious targets of achieving 50% of non-fossil fuel capacity by 2030 and net-zero emissions by 2070. Currently, the country has commissioned approximately 243 GW of non-fossil fuel capacity, with a significant share coming from renewable energy (RE) sources like wind and solar, as illustrated in Figure 1. Notably, India achieved its Nationally Determined Contribution (NDC) target of sourcing half of its power capacity from non-fossil fuels in June 2025—five years ahead of the original deadline.

Figure 1: Source wise power capacity installed

However, a major challenge that persists with RE sources is their intermittent and non-firm nature. These systems are highly sensitive to weather variations, and unpredictable fluctuations in generation can destabilise the grid, especially when large volumes are affected simultaneously.

In this article, we examine the key environmental factors that affect ground-mounted solar PV (GMPV) systems and assess their implications for grid stability and energy planning. 

1. Long-Term Decline in Solar Irradiance

One of the emerging risks to GMPV generation is the long-term reduction in Global Horizontal Irradiance (GHI). In recent years, increased air pollution—particularly in northern India—has significantly diminished the amount of sunlight reaching solar panels. Satellite-based GHI data has shown reductions between 30% to 50% in January 2024 compared to historical averages.

This persistent decline affects annual energy yield estimates, reduces plant performance, and puts financial stress on operators who rely on solar output to meet contractual obligations. The situation is further exacerbated during extended monsoon seasons, which have grown wetter and longer in some regions, leading to a 3% to 10% reduction in GHI during key months. Figure 2 illustrates the monthly decadal averages of GHI for all months of the year, comparing the periods 2005–2014 and 2015–2024. A noticeable decrease in GHI during the latter decade is evident, driven by several of the previously discussed factors.

Figure 2: Comparison of monthly average radiation for two decades

2. Sudden Generation Drops from Traveling Cloud Cover

A more acute risk stems from fast-moving cloud systems that can simultaneously affect multiple GMPV plants across a region. In 2024, India witnessed four instances of over 7,000 MW of generation swing in the western region alone due to such moving cloud formations.

To illustrate the real-time impact of weather on solar generation, we conducted a focused analysis of five GMPV plants located in the Jaisalmer district of Rajasthan. While more plants are operational in the district, this sample serves to effectively highlight the broader issue. Figure 3 presents the installed capacities of these five selected plants.

Figure 3: Installed capacity of GMPV plants under consideration

A closer examination of their 15-minute block-wise generation data reveals significant fluctuations on two specific dates: August 14 and August 24, 2024. These anomalies prompted a deeper investigation. As shown in Figure 4, both days experienced steep drops in output between 1:00 PM and 2:00 PM. On August 14, generation declined by approximately 434 MW within a single hour, while August 24 saw a loss of around 511 MW during the same time frame. 

Figure 4: Generation profile for plants on 14th & 24th August 2024

Satellite imagery reveals that cloud cover first appeared on August 14 and August 24 as seen in Figure 5, leading to a sharp and sudden drop in generation from the GMPV plants. This impact became more pronounced on the following days—August 15 and August 25. However, while the reduced generation continued on these latter days, it did not exhibit the same abrupt fluctuations seen on the initial days of cloud onset. This distinction suggests that the continued low output could have been better anticipated and managed by grid operators. These sharp, rapid declines highlight the disruptive nature of fast-moving cloud cover during the monsoon season and its potential to compromise grid stability within a very short time frame.

Figure 5: Satellite imagery showing cloud cover over Jaisalmer

These sudden drops in generation have immediate consequences on grid frequency, which must be maintained within 49.9–50.05 Hz for stability. Without sufficient ramping capability from firm sources, the grid risks cascading failures or blackouts. This underscores the need for faster-responding balancing mechanisms, such as battery storage systems. 

3. Panel Stowing Due to Hailstorms

Hailstorms pose a dual threat to GMPV installations. First, panels are often stowed at protective angles to avoid damage, resulting in temporary shutdowns of power generation. Second, if not stowed in time or if hail is exceptionally severe, physical damage to panels can further disrupt operations and impose costly repairs.

As climate change increases the frequency and severity of such localized extreme events, stowing-induced curtailments are expected to rise. This adds another layer of volatility that must be accounted for in plant performance modeling and insurance planning.

Implications for the Future

As RE penetration grows and fossil-based backup shrinks, the grid’s exposure to weather-induced generation risks will increase. A future marked by increasingly erratic cloud cover, polluted skies, and convective storms will demand more resilient infrastructure and forecasting capability.

Poor management of these fluctuations can lead to wide-ranging impacts—from frequency instability and load shedding to large-scale blackouts, as recently witnessed in the Iberian Peninsula. Moreover, financial exposure from underperformance can erode investor confidence in solar assets.

Recommendations

To address the growing challenges posed by climate variability, a comprehensive and integrated strategy is essential—one that aligns technological innovation, operational agility, and policy evolution. The following multi-dimensional approach is recommended:

• Adopt High-Resolution Weather Forecasting: Move beyond coarse, static datasets and adopt dynamic, sub-hourly, and location-specific weather forecasting tools. These systems should capture the nuances of fast-moving cloud formations, aerosol-induced irradiance changes, and hailstorm patterns to enable real-time grid response and optimized solar dispatch planning.
• Mainstream Grid-Forming (GFM) Inverters with Battery Energy Storage Systems (BESS): With increasing shares of inverter-based renewable generation, traditional inertia from synchronous machines is rapidly declining. GFM inverters can electronically emulate inertia, providing stability during disturbances by resisting abrupt frequency shifts as seen in Figure 6. These systems are especially effective when integrated with BESS, allowing them to maintain energy and current headroom for grid support. It is observed that at time t’, following the disconnection of the synchronous generator, GFM V₁ and ʘ₁ show no change which is important for grid stability. 

Figure 6: GFL and GFM inverter response at t’ after synchronous generator disconnection

The value of GFM inverters is particularly evident in systems with low Short Circuit Ratios (SCR) (proxy for grid strength)—defined as the ratio of available short-circuit capacity to inverter-based resource capacity. Weak grids with low SCRs are more vulnerable to instability, making GFM inverters, GFM-based HVDC links, and Flexible AC Transmission Systems (FACTS) essential tools to enhance grid strength.

An example illustrated in Figure 7 shows a GFM+BESS system providing synthetic inertia by reducing active power output during an over-frequency event—emulating the behavior of a spinning mass with configurable inertia.

Figure 7: GFM and GFL inverter-based responses to grid frequency variations

• Integrate Energy Storage Systems (ESS) with Grid-Following (GFL) Inverters for Fast Frequency Response (FFR): Not all inverter-based resources need to be grid-forming. ESS paired with GFL inverters can provide FFR by detecting and responding to grid frequency changes within tens to hundreds of milliseconds as seen in Figure 7. While GFMs stabilize the grid in the first few seconds’ post-disturbance, FFR complements inertia by maintaining system frequency in the short term. A balanced mix of GFM and GFL systems is essential for operating low-inertia, high-renewable grids reliably. 
• Policy and Tender Mandates: Follow through on Ministry of Power (MoP) recommendations to include at least 10% energy storage in all future solar project tenders. Such measures will not only improve ramping capability and frequency control but also reduce generation curtailment during adverse weather conditions like hailstorms or cloudy spells.
• Climate Resilience Modeling: Conduct detailed modeling for a variety of weather scenarios—including air pollution-induced dimming, hailstorms, and moving clouds—to design response protocols such as automatic stowing, grid re-routing, or localized battery discharge.

Conclusion

Understanding and preparing for the climatic and meteorological nuances that affect GMPV generation is no longer optional—it’s imperative. As India moves forward on its ambitious clean energy transition, the ability to predict, plan for, and mitigate these disruptions will define the stability and success of its future grid.