How to evaluate the performance of solar panels?

Key performance indicators (KPIs) are crucial for evaluating the efficiency of solar panels and optimising their use. These indicators help to understand how the panels work under different circumstances and how to improve their performance.

The key performance indicators (KPIs) for solar panels

Efficiency

The percentage of solar energy that a solar panel can convert into electricity is known as its efficiency. When choosing a solar panel, this is one of the most crucial aspects to consider.

It is calculated by dividing the electrical power output in watts by the solar power input in watts. This is measured as a percentage.

A higher efficiency panel will require less space to generate the same amount of electricity than a lower efficiency panel. This is critical in places where space is limited or expensive.

Energy production (kWh)

The total amount of electricity produced by a solar panel during a given period, usually expressed in kilowatt-hours (kWh).

It is calculated by adding up the energy produced by the panel over a period of time, e.g. a day or a year.

This measure improves the understanding of the performance of the panel under typical operating conditions. The calculation of the economic viability of a solar installation, the return on investment and the planning of energy consumption are crucial.

Specific yield (W/m²)

The specific efficiency describes the amount of energy produced per unit area of the solar panel. It is a useful measure for comparing the efficiency of different solar panel technologies, regardless of their size.

The maximum power output of the panel (in watts) is divided by its area (in square metres).

It provides a direct assessment of the panel design and technology. The high specific output shows that the panel can generate more energy per square metre, which is useful in installations with limited space.

Measuring the performance of solar panels

Integrated system monitors

Many solar systems have integrated monitors that show the real-time performance of the system. These monitors can show the current energy production and the overall efficiency of the system. They can also alert on any technical problems.

These devices are usually connected directly to the solar inverter and have the ability to provide data accessible through a display on site or remotely via the Internet through a web display.

Energy sensors and meters

Energy sensors are placed at different locations in the solar system to measure the intensity of sunlight, the temperature of the panels and the electrical current produced. This data is essential for evaluating the performance of particular panels. These sensors collect data for operational adjustments, detection of defective panels and optimisation of the orientation and angle of the solar panels to maximise solar collection.

Monitoring applications and analysis software

A wide range of applications and software platforms are available for monitoring solar systems. These tools provide detailed insight into system performance by collecting and analysing data from sensors and system monitors.

These applications allow users to view historical trends in energy production, receive notifications of problems, compare expected versus actual performance and much more. In addition, they can assist in maintenance planning and ROI calculations.

Visual and thermographic inspections

Solar panels need regular inspections with thermal imaging cameras to find physical or electrical problems, such as damaged cells or faulty connections.

Thermography can detect hot spots or inconsistencies in the panels that indicate faults, allowing early interventions to keep the system up and running.

Energy management systems

These systems are more complex and can be integrated with other home or building management systems. They can monitor solar energy production and total building consumption, allowing them to optimise the use of the energy generated.

Based on production and consumption patterns, they provide detailed analysis and suggestions for improving energy efficiency.

Factors that can affect the performance of solar panels

Orientation of the panels

To maximise solar energy collection, solar panels should be oriented towards the sun. To obtain the greatest exposure to the sun in the northern hemisphere, panels are usually oriented towards the south. Incorrect orientation can significantly reduce energy production.

Panel tilt

The amount of sunlight that falls directly on the panels is influenced by their tilt. An optimal angle varies according to latitude and season. A proper tilt ensures that the panels receive the maximum amount of direct solar radiation throughout the year.

Shading

Trees, nearby buildings or other structures that shade the panels can significantly reduce energy output. Partial shading can even affect the performance of the entire system, especially if the panels are connected in series, as it limits the current passing through the shaded panel.

Weather conditions

Weather directly affects solar energy production. Cloudy or rainy days reduce the amount of sunlight available, making the panels less effective. In addition, high temperatures can reduce the efficiency of solar panels because they produce less energy when they are hot.

Dirt and debris build-up

The accumulation of dust, dirt, leaves and other debris on the surface of the panels can block sunlight and reduce their ability to produce energy. To ensure maximum efficiency of the panels, it is essential to keep them clean.

Material ageing

Continued exposure to ultraviolet radiation and climatic variations can cause solar panel materials to deteriorate over time. This can result in a progressive decrease in the efficiency of the panels.

Quality of equipment and installation

The accuracy of the installation and the quality of the solar system components are also crucial. Faulty installation or poor quality components can cause significant energy losses.

System maintenance

Operational problems that are not detected in time, such as loose electrical connections or faulty inverters, can affect the overall performance of the system if regular maintenance is not carried out.

Regular maintenance of solar panels

Perform regular visual inspections to detect physical damage, such as cracks in panels or wear and tear on wiring. These inspections are crucial, especially after extreme weather events.

Make sure electrical connections are tight and free of signs of corrosion. This should be done by a professional at least once a year.

The inverter converts solar energy into electricity. Make sure it shows no error codes and is working properly. The inverter is a crucial component that can affect the performance of the system, so it should be checked frequently.

Check that mounting structures and brackets are secure and undamaged. Components can loosen over time due to movement caused by high winds.

Cleaning of solar panels

The frequency of cleaning depends on the location. Panels may need to be cleaned several times a year in areas with a lot of dust or pollen. Annual cleaning may be sufficient for cleaner areas.

To avoid direct sun exposure, clean the panels early in the morning or in the evening. Also, to reduce the risk of damage, make sure the panels are cool to the touch.

Clean the panel surface with water and a soft cloth or squeegee. Avoid using abrasive soaps or detergents that may leave residue or damage the surface.

Ingrained dirt can scratch the panels if you use sharp or abrasive objects. Use a soft brush or more water if you encounter stubborn stains.

Consider hiring professionals who use specialised equipment to clean large installations or panels placed in hard-to-reach areas.

Interpret the performance data of the solar panels.

Step 1: Data Collection

Having access to energy production data is necessary before performance can be analysed. This is usually achieved through:

System monitors: these devices provide real-time and historical data on energy production and other important system parameters.

Sensors and meters: provide more detailed information on particular factors such as solar irradiation, temperature and conversion efficiency.

Step 2: Data Analysis

The next step is to analyse the data to understand the behaviour of the system:

Compare with baseline data: use simulations or historical data to compare current energy production with expected values.

Identify patterns and anomalies: Examine the data to find patterns that may indicate problems, such as a decrease in energy production during certain times of the day that could indicate shading.

Inverter efficiency: An assessment of inverter efficiency, which can decrease over time and have an impact on total energy production.

Seasonal and weather effects: Take into account seasonal changes and weather conditions that may affect energy production, such as fewer hours of sunlight in winter or increased soiling of the panels during dry and dusty seasons.

Step 3: Diagnose problems

If you observe any variations or decreases in production, consider the following possible causes:

Physical inspections: Perform physical inspections to find visible panel damage or installation problems.

Check components: Ensure that all system components, such as cables and connections, are in good condition.

Shading check: Take into account shading effects that may change over time, such as the growth of nearby trees.

Step 4: Adjustments and improvements

Based on your analysis, choose which changes could improve performance:

Cleaning and Maintenance: schedule regular cleaning and maintenance based on periods when you notice a decrease in performance.

Readjusting the panels: If possible, change their orientation or tilt to capture more direct sunlight.

System Upgrades: There may be an upgrade to system components, such as purchasing a more efficient inverter or adding more panels to compensate for low output.

Step 5: Implementation and ongoing monitoring

It makes required adjustments and monitors their impact on system performance. To create a continuous feedback loop, it adjusts maintenance and operation strategies as needed, using performance data.

Conclusion: Compare current performance

To effectively evaluate the efficiency of a solar system, it is necessary to compare its current performance with previous estimates and industry standards. This process helps solar system owners and operators identify areas for improvement and determine whether the installation is performing as expected. Listed below are some key points about the relevance of this comparison:

Owners can confirm that the system is generating the expected amount of energy and performing correctly by comparing actual data with estimates and benchmarks. This is critical to ensure that production expectations and return on investment are met.

This comparison helps to quickly identify any deviations from expected performance, which may be a sign of technical problems, unplanned shading or a need for maintenance. Timely resolution of these problems can prevent significant efficiency losses and extend the life of the system.

Based on the results of the comparison, modifications can be made to improve performance, such as changing the orientation of the panels, adjusting their tilt or even upgrading system components such as the inverter.

Evaluating the efficiency of the system in comparison to other similar systems is also facilitated by comparison with industry standards. This can be useful in determining whether new technologies or operational techniques need to be implemented to remain competitive.

Understanding how the system performs compared to expectations allows operators to better plan both financially and operationally. They can adjust their revenue generation expectations based on the amount of energy they generate, as well as optimise operation and maintenance costs.

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