A solar PV weather station provides site-specific data on the environmental conditions that directly affect photovoltaic power generation. The efficiency of a solar PV plant depends on more than the specifications of its photovoltaic modules and inverters. Power generation is constantly affected by solar irradiance, cloud cover, air temperature, wind speed, and other weather parameters.
If an operator can only see actual power output, part of the picture remains outside the monitoring system. A drop in generation may be caused by changing weather conditions, soiling of the panels, module degradation, or equipment issues. Without accurate data on the conditions at the site, identifying the cause of a deviation becomes much more difficult.
This is why a modern weather monitoring station for a solar PV plant is more than a source of weather information. Site-specific weather data can be used to assess the site’s energy potential, forecast generation, monitor plant performance, diagnose deviations, and automatically respond to adverse weather conditions.
Why Solar PV Plants Need On-Site Weather Monitoring
The performance of a solar PV plant is directly linked to the amount of solar irradiance reaching the PV array. However, irradiance alone is not enough for a complete analysis.
Air temperature, cloud cover, wind, humidity, and other environmental factors can also affect plant performance. This makes it important not just to use a regional weather forecast, but to measure conditions directly at the site.
A local automated weather station builds a dedicated history of observations for a specific solar PV plant. This allows operators to compare actual generation with the real conditions under which the equipment was operating at any given time.
At the project assessment stage, weather data helps determine the energy potential of a site. Solar irradiance measurements provide a basis for estimating future energy yield and modelling plant performance.
Once the plant is commissioned, the same data can be used for operational monitoring. Actual generation can be compared with expected output to identify situations where plant performance does not match the prevailing weather conditions.
In this way, PV weather monitoring moves the focus from simply recording energy output to understanding the factors that drive it.
Solar Irradiance Monitoring for PV Performance Analysis
For a comprehensive assessment of a solar PV plant, solar irradiance is one of the key parameters to monitor. Depending on the project configuration, a weather monitoring station may measure global horizontal irradiance (GHI), plane-of-array irradiance (POA), ambient temperature, module temperature, wind speed, wind direction, humidity, atmospheric pressure and rainfall.
These measurements provide the environmental context needed to evaluate plant performance.
For example, if solar irradiance remains high but the plant’s power output drops significantly, weather conditions can be ruled out as a likely cause. The investigation can then focus on potential technical issues such as panel soiling, changes in module performance, or equipment faults.
If irradiance decreases at the same time as power output, however, the change in generation may primarily be explained by natural external conditions.
This makes a weather station an additional tool for PV performance monitoring and diagnostics. It does not replace the monitoring system for the plant’s electrical equipment; instead, it provides the environmental context needed to interpret its data.
Solar Power Generation Forecasting
One of the key applications of weather monitoring at a solar PV plant is short-term solar power generation forecasting.
This requires up-to-date data on solar irradiance, cloud cover, wind speed, temperature, and other weather parameters. Analysing these inputs makes it possible to estimate changes in generation over the next few minutes or several hours.
For plant operators, this provides advance visibility into potential changes in power output. For the wider power system, this is particularly important because solar generation is inherently variable.
If a decrease or increase in generation is expected, the information can be taken into account when balancing electricity supply and demand. More accurate PV power forecasting helps grid operators plan the required capacity in advance and reduce the impact of sudden changes in solar output.
Weather data is therefore not only useful for analysing events after they happen. It enables a more proactive approach to plant operation.
Monitoring the Actual Performance of Solar PV Plants
For a solar PV plant, it is important to know not only how much energy was generated, but also whether that output is consistent with the current external conditions.
Consider a situation where solar irradiance remains high, but the plant’s power output drops significantly. If the operator has access to site-specific weather data, weather conditions can be ruled out as a likely cause and the investigation can focus on a potential technical issue.
Possible causes may include soiling of the panel surface, changes in the performance of individual modules, or equipment failure.
If solar irradiance decreases at the same time as power output, however, the change in generation may primarily be explained by natural external conditions.
By combining environmental measurements with electrical data, operators can distinguish weather-related changes from potential technical deviations and investigate problems more efficiently.
The Impact of Weather Monitoring
Depending on the plant configuration and operating conditions, weather monitoring can contribute to:
- up to 1.5–4% higher annual energy yield
- up to 20% fewer unplanned outages
- a 1–3% increase in Performance Ratio
- additional protection for PV structures during high-wind conditions.
Actual results depend on the plant, equipment, operating conditions, and implementation of the monitoring system.
Weather Data for Solar PV Equipment Protection
Weather data can be used not only for analysis and forecasting, but also for the automatic protection of solar PV plant equipment.
Strong winds are one example. For plants equipped with movable structures or solar tracking systems, wind speeds above a defined threshold can create additional mechanical loads.
With real-time data from weather sensors, the control system can respond to adverse conditions and move the panels into a safe position.
Temperature is another important factor. Continuous temperature monitoring makes it possible to account for conditions that may increase the risk of equipment overheating.
Weather data can also serve as an input for auxiliary systems, such as panel cleaning or anti-icing systems.
In this case, weather monitoring becomes part of the plant’s automation system: it does not simply record environmental conditions, but allows those conditions to be taken into account when operating the plant.
Weather Data for Diagnosing Performance Deviations
The practical value of weather monitoring becomes particularly clear when analysing abnormal operating conditions.
Suppose actual generation falls below the expected level.
Instead of immediately looking for equipment failure, an operator can systematically compare plant performance with the environmental conditions:
- Check the level of solar irradiance.
- Review changes in temperature and other weather parameters.
- Compare weather data with the generation profile.
- Determine whether the deviation can be explained by external conditions.
- If not, proceed to diagnose the electrical and power equipment.
This approach can help identify the source of a problem faster and distinguish weather-related effects from technical issues.
Weather Data for Energy Contracts and Performance Verification
Local weather monitoring also has another important function: documenting the conditions under which electricity was generated.
When analysing deviations between planned and actual energy output, historical weather data can show what conditions were observed at the site during the relevant period.
Site-specific data provides an independent information base that can be used to analyse plant performance and assess compliance with contractual obligations.
The Sokol Meteo approach describes this principle as creating a common information language between the investor, operator, and power system.
Weather data provides context for energy performance: not only how much electricity was generated, but also the actual conditions under which the plant operated.
Weather Data for Solar Project Planning and Feasibility Studies
Weather monitoring is useful not only for operating solar PV plants, but also for evaluating new projects.
Long-term observations create a valuable data set for assessing potential sites. The more data available on actual conditions at a specific location, the more accurately its energy potential can be evaluated.
Historical measurements can be used:
- when preparing feasibility studies
- to estimate future plant performance
- to build financial models
- to calculate ROI
- for strategic planning of new and existing assets.
Instead of relying solely on average regional figures, investors can use data collected directly at the site under consideration.
Once the plant is commissioned, the same data set continues to support day-to-day operations, including performance monitoring, diagnostics, and further forecasting.
A dedicated historical database can help:
- analyse seasonal patterns
- compare actual conditions across different periods
- identify the causes of deviations
- improve generation forecasting
- plan plant operation and future development.
Sokol-M1 Weather Station for Solar PV Plants
For a comprehensive analysis of a solar PV plant, solar irradiance alone is not enough. Plant performance and operating conditions depend on multiple factors, so the weather monitoring system should be configured to meet the specific requirements of each site.
The Sokol-M1 automated weather station measures the key meteorological parameters required for solar PV monitoring. Additional sensors can also be integrated to expand the range of measurements depending on the plant design, site conditions, and monitoring requirements. The final configuration should take into account the required parameters, including solar irradiance, as well as the method used to transmit data to the plant monitoring system.
