Beyond the Breeze: How Solar Power Prevents Renewable Energy Droughts

Introduction

The demand for electrical energy is increasing continuously due to the rapid growth of industries, technology and modern lifestyles. However, there is also a growing need to reduce greenhouse gas emissions and move towards sustainable energy sources. Renewable energy resources such as wind and solar power have become extremely important in solving this problem.

Nevertheless, these sources depend heavily on weather conditions. Sometimes, long periods of low renewable energy generation occur, creating what scientists call Renewable Energy Source (RES) droughts. These events can affect energy security and make it difficult to satisfy electricity demand.

This investigation focuses on the relationship between wind power and solar photovoltaic (PV) systems. Specifically, it explores how increasing photovoltaic (PV) capacity can reduce the frequency and duration of renewable energy droughts. Through this combination, energy systems can become more resilient and dependable for future generations.

The Framework Behind RES Droughts

RES droughts refer to periods where renewable electricity generation remains below a particular threshold for an extended duration. In this investigation, a drought occurs when the average capacity factor remains below 0.1 for more than twenty-four hours.

Capacity factor (CF) measures the amount of electricity produced compared to the maximum amount that could potentially be generated. Lower values indicate weaker renewable energy production.

The researchers analysed three different datasets to study these events. Two datasets originated from the Copernicus Climate Change Service (C3S-Energy), while the third dataset was produced using the Atlite model. The models used atmospheric variables such as wind speed, temperature and solar radiation obtained from the ERA5 reanalysis database.

The study compared two different energy systems. The first system consisted mainly of wind energy with a small proportion of photovoltaic (PV), while the second system contained a more balanced combination of both renewable sources. This comparison allowed the researchers to investigate whether diversification could reduce energy shortages.

Beneath the Surface of Renewable Energy Droughts

Weather conditions play a crucial role in determining renewable energy generation. Wind turbines require sufficient wind speeds to operate efficiently, whereas photovoltaic (PV) panels depend on sunlight intensity and duration.

During summer, wind generation in Ireland tends to decrease, causing more frequent wind droughts. In contrast, solar energy performs better due to longer daylight hours and stronger solar radiation. During winter, the opposite occurs, with wind generation increasing while solar output becomes significantly lower.

This complementary relationship provides an important advantage. When one renewable source experiences lower production, the other can compensate for the shortage. Consequently, combining wind and solar power reduces the likelihood of prolonged RES droughts.

The movement towards a balanced renewable system therefore increases resilience and provides a more stable electricity supply throughout the year.

The Hidden Challenges

Initially, several difficulties emerged in the investigation of RES droughts.

Firstly, many generic renewable energy datasets do not accurately represent local conditions. The selection of these wind turbine models or photovoltaic (PV) characteristics can lead to incorrect estimates of renewable generation. As a result, the frequency and duration of drought events may be underestimated.

Secondly, renewable energy itself depends entirely on changing weather conditions. Wind patterns and sunlight intensity fluctuate throughout the seasons, making energy production unpredictable at certain times of the year.

Thirdly, even though increasing photovoltaic (PV) capacity improves overall resilience, winter droughts still remain a major concern. Northern European countries experience their highest electricity demand during winter, precisely when solar generation reaches its lowest levels.

Therefore, careful planning, reserve capacity and accurate modelling systems are necessary to ensure long-term energy security.

Outcome of the Investigation

The paper analysed 45 years of hourly renewable generation time series derived from weather reanalysis data, rather than raw weather data alone.

The results demonstrated that adding greater amounts of photovoltaic (PV) to a wind-dominated system significantly reduced the number and duration of drought events. In the balanced 57W-43PV scenario, the total number of renewable energy droughts decreased by approximately fifty percent compared to the current energy structure.

Furthermore, extreme drought events became much less common. A five-day renewable drought that previously occurred every few months could instead occur only once every several years under the diversified system.

These findings highlight the importance of combining different renewable resources to create a stronger and more reliable energy network.

The Importance of Renewable Diversification

The integration of wind and solar power provides a sustainable solution to the challenges created by weather-dependent energy generation. Rather than relying heavily on a single renewable source, diversification allows one system to compensate for the weaknesses of another.

This approach improves energy security, reduces the severity of renewable energy droughts and strengthens resilience against extreme weather conditions. It also supports global efforts towards decarbonisation while maintaining a dependable electricity supply.

As countries continue their transition towards cleaner forms of energy, balanced renewable systems may become essential in achieving both environmental and economic sustainability.

Summary:

Renewable Energy Source (RES) droughts are periods of low renewable electricity generation caused by weather conditions. This investigation compared different datasets and examined how combining wind and photovoltaic (PV) affects these events. The results showed that generic models may underestimate drought risks if they are not adapted to local conditions. Increasing photovoltaic (PV) capacity alongside wind power reduced both the frequency and duration of RES droughts by nearly half while making extreme events less common. This demonstrates that diversified renewable systems can improve energy security and strengthen resilience as nations move towards a sustainable future.

Bibliography

Morin, B., Maimó Far, A., Flynn, D., & Sweeney, C. (2025). Reducing RES droughts through the integration of wind and photovoltaic (PV). Renewable Energy, 252, 123392. https://doi.org/10.1016/j.renene.2025.123392

Aishwarya Pillai | Writer | The STEM Review