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String Monitoring and its Advantages

Solar power plants are the crucial elements in our electricity system for generating clean and sustainable forms of energy. For maximizing the output of solar power plants, proper string monitoring is essential. One of the important aspects of monitoring solar arrays is the string that connects the solar panels. We must design a comprehensive string maintenance checklist to ensure that solar plants work at their maximum. Some points are elaborated below.

What is String in Solar Panel?

Strings refer to a specific configuration of solar panels electrically connected in series. Strings are a vital part of solar panel photovoltaic systems. Sizing strings in a solar panel is an important task. It involves determining the number of solar panels connected in series to form a string. We can use the below formula. 

Number of panels in a string N =Inverter maximum DC input voltage vdc / max open circuit voltage voc 

What is String Monitoring?

String monitoring is like keeping an eye on all the strings of solar panels to see how well each one is working. It helps us know the performance of each panel and the whole solar panel system. The main goal is to check the current and voltage of each string in real-time. We also measure the temperature inside the box to make sure everything is okay. The information about current, voltage, and temperature is sent through a cable using Modbus protocol. This helps us quickly find and fix any problems in any string. There are two ways to do string monitoring: using a solar inverter-based system or using a separate string monitoring system from another company.

Futr Energy helps to identify the exact point of failure in the solar PV system. Having a string monitoring system in the plant eliminates both these problems and allows the maintenance team to track the correct location of the problem and fix it in the minimum time possible.

Role of String Monitoring

String monitoring plays an important role in the efficient and reliable operation of solar power plants. Monitoring of individual strings of solar panels allows for real time performance, early issue detection, and informed decision making. String monitoring in a solar power plant is essential for maintaining peak performance, detecting faults, optimizing efficiency, and preventing energy loss by closely monitoring and managing the performance of each string of solar panels. Some of the key roles and benefits of solar string monitoring are mentioned below.

⦁ Early issue detection

⦁ Optimizing system performance

⦁ Predictive maintenance

⦁ Maximizing energy output of solar plant

⦁ Regulatory compliance and reporting

⦁ Safety assurance and remote access management

What is a Solar Monitoring System?

Solar monitoring systems are essential for maximizing the effectiveness of your solar plants. They continuously observe and analyze the performance, health, and energy consumption of your solar power plants. These systems also monitor specific components, such as solar batteries and electric vehicle (EV) chargers. In the event of a decrease in energy output or system malfunctions, these monitoring systems promptly generate alerts, ensuring the smooth operation of your solar setup.

How Do Solar Monitoring Systems Work?

Solar monitoring systems use sensors and communication devices on solar arrays to track production data. This information is transmitted to a gateway via hardwiring, internet (ethernet or wifi), or cellular technology, which then sends it to a cloud-based software application. In addition to real-time monitoring, some systems issue alerts for solar system issues or declining power production. These alerts help identify problems quickly, minimizing potential system downtime. Some systems also offer weather alerts for low-sunlight days or storms, facilitating proactive planning and ensuring efficient stored solar power for later use.

Advantages of a String Monitoring System

Let’s talk about why having a string monitoring system is a good idea. In a solar power setup, each “string” is a group of solar panels linked together. Imagine you’ve set up a 500 kWp solar power system, and each string has 10 solar panels connected in a row.

Now, suppose one of the solar panels in a string gets damaged or has a loose connection on a sunny day. You might not notice a big drop in overall power production because it’s just a small part of the whole system. You might think the slight reduction is due to normal things like weather changes or temporary shading.

But here’s the catch: those 10 panels in the affected string are actually not producing any power. That adds up to a loss of nearly 15 units per day. A string monitoring system helps you figure out the real reasons for the drop in production. It lets you track and fix issues quickly, so you don’t lose out on valuable energy.

String Configuration and Design:

We must ensure that string layout, voltages, and currents are systematic here. 

String Layout:

We must ensure the layout is according to the manufacturer’s design and optimized for space and lighting constraints. 

String Voltages and Currents:

Suppose we use an inverter at the end to provide the energy to an AC load. In that case, we need to ensure that the voltages and currents of each string are within the specified range to prevent overloading and underutilizing the inverter capacity.

String Length and Number of Panels:

Ensure the string has the correct number of panels and appropriate length to match the specifications of the inverters. 

String Monitoring Equipment

Maintaining the optimal performance of solar panel string monitoring equipment is a basic requirement. This includes.

String Level Monitoring System:

Install a string-level monitoring system for robust real-time monitoring of each string. We can detect early issues through a level monitoring system, Compatibility with inverters, and alerts and notifications.

Data Logging:

Set up data logging to record the historical performance of strings. This data will be important for trend analysis and identifying issues simultaneously.

String Health and Performance Checks

 We must inspect the strings’ temperatures, voltages, and current levels for string health and performance checks.

Voltage and Current Monitoring:

Regularly monitor and check each string’s voltage and current level with the help of a meter; this will help detect deviations from the targeted value. Sudden drops or spikes may indicate issues with panels or wiring. 

By this, we can maximize the string efficiency,

  • Actual Power Output can be measured directly from the inverter or monitoring system.
  • Expected Power Output is calculated as the sum of the maximum power ratings of all panels in the string.

Temperature Monitoring:

Excessive heat can reduce panel efficiency, so we must keep track of temperature. We can mitigate the issue of overheating by implementing certain procedures, such as proper ventilation and shading.

Module-Level Monitoring:

Module-level monitoring helps pinpoint individual module-level issues and identify faulty panels.

Regular Maintenance:

Regular maintenance can be done by:

Visual Inspection:

 Conduct a visual inspection to determine any damages, loose connections signs, or wear and tear. We can check the performance ratio by using the formula.

  • Actual Yield is the actual energy output in kWh.
  • Irradiance is the solar energy received on the panel’s surface (measured in W/m²).
  • The area is the total area of all panels in the string.

Cleaning:

Dirt, dust, and debris on panels also affect their efficiency, so ensure regular cleaning to generate more energy.

Data Analysis and Troubleshooting 

Data analysis and troubleshooting can be done with the help of data analysis tools and remote monitoring.

Analysis Software:

The data analysis software is very useful for pattern detection, anomaly detection, historical trend analysis, and performance benchmarking.

Remote Monitoring:

For real-time monitoring and rapid response time, remote monitoring is special.

Emergency Response Plane 

Develop an emergency response plan to look into the issues promptly from the string-level monitoring system and train the maintenance team to respond to emergencies effectively.

Conclusion:

String monitoring is a vital component of solar power plant maintenance and optimization. Following the points mentioned earlier, we can ensure that our solar panels work at their maximum potential and contribute to sustainable energy.

Click here to download Sample file for String Monitoring Checklist

Originally published at futr.energy/knowledge

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