In a new solar plant, establishing a ranking system—often used to compare inverter blocks, string performance, or site-to-site efficiency—requires a balance of leading indicators (proactive, predictive metrics) and lagging indicators (reactive, historical results).

 Shri SKB Valli Sir in morning meeting asking to all to know leading and lagging indication in plot , block performance.

In a new solar plant, establishing a ranking system—often used to compare inverter blocks, string performance, or site-to-site efficiency—requires a balance of leading indicators (proactive, predictive metrics) and lagging indicators (reactive, historical results). For a new, high-performance plant, leading indicators are critical to identify issues before they significantly impact revenue. 

Key Leading Indicators (Predictive of Future Performance)

These metrics signal potential future failures or performance degradation, allowing for corrective maintenance before production drops. 

String-Level DC Current Imbalance: Identifying individual strings producing less than neighbors, signaling soiling, shading, or damaged panels (e.g., PID).

Inverter/Converter Efficiency & Clipping Ratio: Monitoring if inverters are clipping (capping output) correctly based on DC/AC ratios; if an inverter runs below expected, it suggests DC health issues.

Thermal Monitoring (Module/Inverter Temperature): High temperatures significantly reduce efficiency; tracking this allows for proactive cooling or ventilation fixes.

SCADA Data Availability/Accuracy: A low rate of data transmission is a leading indicator of communication faults.

Soiling Rate/Soiling Loss Trend: Tracking the accumulation of dirt on panels to optimize cleaning schedules before significant energy is lost.

Transformer/Inverter Alarms & Trips: Early warnings on equipment health (e.g., DC insulation resistance, noise levels). 

Key Lagging Indicators (Measures of Past Results)

These metrics measure the final outcome of the day, month, or year. While essential for financial and contractual compliance, they do not help in preventing failures that have already occurred. 

Performance Ratio (PR): The most common metric, comparing actual energy produced to theoretical energy potential based on irradiance. A high PR (usually 75-85%) signals a well-functioning plant.

Specific Yield (kWh/kWp): The energy generated per unit of installed capacity, allowing comparisons across different sized plants or blocks.

Capacity Utilization Factor (CUF): Measures how effectively the plant uses its capacity over time.

Actual vs. Expected Energy Production (kWh): The variance between the forecasted generation and real-time generation.

Plant/Inverter Availability (Uptime): The total time the plant is available to produce power; contractual availability typically targets >98%.

Degradation Rate: The annualized loss in energy output as the plant ages. 

Implementing a Ranking System

A balanced ranking system for a new solar plant might, for instance, rank inverter blocks based on: 

30% - 7-day Average Performance Ratio (Lagging)

30% - 7-day Specific Yield (Lagging)

20% - Real-time Inverter Availability (Leading)

20% - Daily String Current Imbalance (Leading) 

This allows managers to reward high-performing blocks (via lagging metrics) while immediately identifying which areas need maintenance before the next month's report (via leading metrics.

In a new solar plant, implementing a "lEHSQ" (Leading Environmental, Health, Safety, and Quality) ranking system involves tracking proactive actions (leading) alongside final outcomes (lagging). For a new plant, leading indicators are critical to establishing a proactive safety culture and identifying construction or commissioning defects before they cause long-term performance issues. 

Key EHSQ Indicators for Solar Plant Ranking

1. Leading Indicators (Proactive/Predictive)
These metrics signal future performance and allow for early intervention to prevent accidents or equipment failure. Safety Training & Induction Rates: Percentage of staff completing site-specific safety inductions and specialized training (e.g., high-voltage safety).

• Safety Observation Rates: Number of hazard reports, near-miss reports, or safety observations (e.g., inverters, cabling) filed per employee, indicating engagement.
• Preventive Maintenance (PM) Completion: Percentage of scheduled maintenance tasks on trackers, inverters, and modules completed on time.
• Safety Audits/Inspections: Frequency of site safety audits and management site visits.
• Permit-to-Work (PTW) Compliance: Percentage of tasks performed with valid, filled-out permits.
• Equipment Commissioning Checklists: Completion rate of pre-commissioning checks, including thermographic imaging of panels and I-V curve tracing. 

2. Lagging Indicators (Reactive/Outcome-Based)
These metrics measure historical outcomes and validate the effectiveness of proactive measures. Total Recordable Incident Rate (TRIR): Total number of injuries or illnesses.

• Lost Time Injury Frequency Rate (LTIFR): Number of lost time injuries per million man-hours.
• Environmental Spills/Releases: Number of environmental breaches or hazardous material spills.
• Non-Conformance Reports (NCRs): Number of quality issues found during inspections.
• Grid Compliance Failures: Number of times the plant violated grid connection requirements. 

Indicators for Plant Ranking System (Performance & Quality) For ranking new plants, EHSQ is combined with operational KPIs to ensure quality:

• Performance Ratio (PR) Test: The Actual Yield vs. Theoretical Yield. A high PR (usually 
  

  $>80\%$
  ) indicates high-quality installation and minimal, early-stage, in-factory, or shipping damage.
• Specific Yield (kWh/kWp): Normalizes output to allow comparison between different-sized plants.
• System Availability (%): Percentage of time the plant is capable of producing energy, indicating the reliability of the installed equipment.
• SCADA Data Availability: Percentage of time the monitoring system is fully functional, ensuring visibility of the plant. 

Implementing the Ranking System

1. Dashboard Integration: Use SCADA data to feed, in real-time, both performance (PR) and EHSQ (e.g., near-misses) into a central dashboard.
2. Weighted Scoring: Assign higher weightings to leading indicators during the first 6–12 months of operation (e.g., training, safety observations) to build culture, shifting towards more weight on lagging indicators (e.g., TRIR, PR) as the plant matures.
3. Proactive Maintenance: Use leading indicators to trigger maintenance before a lagging indicator (like total plant downtime) occurs.