Photovoltaic installations and the optimisation of their generation on cloudy days

Photovoltaic installations have become one of the fundamental pillars of the energy transition in Spain and across Europe. Their ability to convert solar radiation into clean electricity makes it possible to reduce dependence on fossil fuels and cut CO₂ emissions. However, their production is closely linked to weather conditions, with cloudy days being one of the main factors affecting variability in generation. In this context, proper operation and maintenance is essential to ensure that solar plants maintain acceptable production levels even under low-irradiance conditions.

When the sky is covered by clouds, the amount of direct solar radiation reaching photovoltaic modules decreases. Clouds scatter light, reducing the intensity with which photons strike the solar cells. As a result, the electrical current generated is lower and the power output of the installation decreases. Nevertheless, panels do not stop working completely, as they still capture diffuse radiation. A well-designed operation and maintenance strategy makes it possible to maximise the use of this available radiation and minimise production losses.

The impact of cloud cover on solar panels depends on the type and density of the clouds. Low, thick clouds reduce irradiance much more than high, thin clouds. In any case, modern photovoltaic modules are designed to operate under different light levels. However, without proper operation and maintenance, even small system deficiencies can lead to significant losses when the available radiation is limited.

One of the most important aspects of operation and maintenance is the cleaning of solar panels. On cloudy days, any accumulated dirt—dust, sand, bird droppings or pollution—further reduces the amount of light reaching the photovoltaic cells. Since solar radiation is already low, the relative impact of soiling is even greater than on clear days. For this reason, a regular cleaning plan is essential to maintain optimal performance throughout the year.

The inspection of electrical components is also a fundamental part of operation and maintenance. Under low-irradiance conditions, losses caused by faulty connections, damaged cables or poorly adjusted inverters become more critical. A minor electrical fault can lead to a significant loss of generated energy. Regular technical inspections help detect and correct these problems before they seriously affect production.

Another key element is the mounting structure and the orientation of the panels. The tilt and azimuth are designed to optimise annual energy capture, but they can be altered over time by wind, structural movement or ground settlement. Proper operation and maintenance includes verifying that the structures remain correctly aligned, ensuring that the modules capture as much radiation as possible, including the diffuse radiation typical of cloudy days.

Continuous monitoring of the photovoltaic system is an essential tool to optimise generation. Monitoring systems allow real-time analysis of plant performance, making it possible to detect abnormal drops in output and take prompt action. On days with low solar radiation, monitoring helps distinguish between a normal weather-related decrease and a loss caused by a technical fault.

Inverters play a crucial role in power generation on cloudy days. Modern equipment is designed to operate efficiently at low voltages and currents, maximising the conversion of the energy captured by the panels. Operation and maintenance should include software updates, calibration and, when necessary, the replacement of older inverters with more efficient models.

Shade management is another important factor. On cloudy days, any additional shading can further reduce production. Trees, nearby buildings or even parts of the plant itself may block light from reaching the modules. As part of operation and maintenance, it is essential to periodically review the surroundings and remove or reduce these obstacles to improve overall performance.

The incorporation of technologies such as power optimisers or microinverters also helps improve generation under low-irradiance conditions. These devices allow each module to operate independently, preventing the performance of one shaded or poorly illuminated panel from affecting the rest. Integrating these solutions into an advanced operation and maintenance strategy can make a significant difference on cloudy days.

Finally, the training of technical staff is a basic pillar of operation and maintenance. A well-qualified team can correctly interpret production data, identify deviations and apply corrective measures quickly and effectively. This helps keep the installation in optimal condition and maximise energy output even when weather conditions are not favourable.

In conclusion, although cloudy days inevitably reduce the output of photovoltaic installations, their impact can be minimised through proper operation and maintenance.. Cleaning monitoringechnical inspections and equipment optimisation make it possible to make the most of the available radiation ensuring more stable and efficient generation. In this way, good operation and maintenance not only protects the investment but also guarantees maximum energy performance throughout the system’s lifetime. .