Accuracy Requirements in Solar Trackers per IEC 62817

By Irfan Akhtar & Ramy Adel Barakat

Introduction

Solar trackers play a pivotal role in maximizing the efficiency of photovoltaic (PV) systems by enabling solar panels to follow the sun’s trajectory. However, the performance of solar trackers is highly dependent on their accuracy. The IEC 62817 standard outlines stringent requirements to ensure that solar trackers deliver reliable and efficient performance, with a critical focus on accuracy and durability.

Key Accuracy Requirements

The IEC 62817 standard specifies that solar trackers must achieve an accuracy of ±5° to capture 99.6% of the available direct beam energy. This accuracy benchmark ensures that trackers align with the sun’s position throughout the day, minimizing energy losses.

Significance of ±5° Accuracy:

? A deviation beyond this threshold results in a notable reduction in energy yield.

? Precision is crucial in concentrating PV systems and bifacial modules, which are more sensitive to misalignment.

Design Constraints: Torsional and Structural Integrity

1. Torque Tube Design

The torque tube is a critical component in solar trackers, serving as the main structural element that rotates the PV modules. The IEC 62817 standard indirectly imposes constraints on the torsional deflection of the torque tube to maintain tracking accuracy.

? Torsional Limitation: The torque tube must have minimal twisting under load. Excessive twisting can lead to misalignment of the modules and reduced energy capture.

? Maximum Allowable Twist Angle: Industry best practices recommend limiting the torsional deflection to less than 0.5° per meter of torque tube length to meet the ±5° system accuracy requirement.

2. Wind Loading Considerations

Solar trackers are exposed to dynamic wind loads that can induce structural vibrations and misalignment. The IEC 62817 standard emphasizes:

? Stiffness: Materials and structural design should ensure that wind-induced deflection does not exceed the allowed angular deviation.

? Damping Mechanisms: Effective damping systems reduce oscillations and maintain stability during high winds.

3. Control System Precision

The tracker’s control system must include sensors and actuators capable of maintaining the required accuracy. Key elements include:

? High-resolution sun sensors.

? Precise motor control algorithms.

? Compensation for temperature-induced material expansion/contraction.

Best Practices for Compliance with IEC 62817

To achieve and maintain the required accuracy, manufacturers and designers should adopt the following practices:

Material Selection

? Use high-strength steel or aluminum alloys for torque tubes to minimize deflection.

? Implement anti-corrosion treatments to ensure long-term structural integrity.

Structural Design Optimization

? Employ finite element analysis (FEA) during the design phase to predict torsional behavior under various load conditions.

? Optimize the shape and thickness of torque tubes to balance weight and stiffness.

Tracking Algorithm Enhancement

? Develop tracking algorithms that compensate for environmental factors such as wind, temperature, and module weight.

? Integrate real-time feedback systems for continuous alignment corrections.

Testing and Validation

? Conduct comprehensive on-site and laboratory tests to verify compliance with IEC 62817.

? Perform endurance tests to evaluate long-term performance under simulated environmental conditions.

Call for Expert Discussion

The solar industry continues to innovate in materials, control systems, and designs to meet and exceed the accuracy requirements set by IEC 62817. However, questions remain:

? What are the emerging trends in torque tube materials to further reduce twisting angles?

? How do advanced tracking algorithms improve long-term accuracy under varying conditions?

? Are there additional enhancements to mitigate wind-induced vibrations?

By sharing insights and expertise, we can drive advancements in solar tracking technology and contribute to the growth of renewable energy solutions.

References

1. IEC 62817: “Photovoltaic Systems – Design Qualification of Solar Trackers.” International Electrotechnical Commission.

2. Solar Energy Industries Association (SEIA): Solar Tracker Best Practices.

3. G. Wu et al., “Analysis of Torque Tube Torsion in Solar Tracker Systems,” Journal of Solar Energy Engineering, 2023.

4. National Renewable Energy Laboratory (NREL): “Impact of Tracking Accuracy on PV System Performance.”

Conclusion

Adhering to the accuracy requirements defined in IEC 62817 is crucial for optimizing solar tracker performance and ensuring maximum energy output. By focusing on material selection, structural integrity, and control precision, the industry can meet these stringent standards while fostering innovation. Let’s collaborate to enhance solar technology and pave the way for a sustainable future!