Solar plants are exposed 24×7 to environmental and electrical hazards. Among the most underestimated aspects of solar design is proper earthing and lightning protection. Time and again, poor grounding has led to equipment damage, inverter failures, and even fire risks — often due to simple yet critical mistakes during installation.
In this blog, we’ll cover the top 5 earthing/Lightening Arrestors mistakes, with real case studies, best practices, and technical recommendations — helping you design safer, more reliable solar plants.
This blogs not only covers the common mistakes but is a Complete Technical Guide on Grounding and Lightning Protection for Solar Projects covering the basics so that even a novice can understand it.
❌ Mistake 1: High Earth Resistance in Poor Soil Conditions
🧪 Case Study: 500 kWp Plant – Rocky Terrain, Ranchi
- Problem: Frequent inverter shutdowns during power fluctuation.
- Diagnosis: Earth resistance measured ~12 ohms per pit.
- Cause: Rocky terrain, shallow rods, no chemical backfill.
- Impact: Intermittent tripping and system unreliability.
✅ How to Avoid It:
- Use chemical earthing rods with backfill compound (BFC) in rocky or dry soil.
- Ensure resistance < 1 ohm for sensitive equipment.
Conduct proper soil resistivity testing before designing the grounding system.
⚡ Mistake 2: Improper or Missing Lightning Arrestors
🌩️ Case Study: 400 Kw Plant- in Jamshedpur
- Problem: A lightning strike damaged 3 inverters.
- Cause: Conventional rod installed at the wrong height and position. No proper earthing or SPD installed.
- Loss: ₹6 lakh in equipment replacement.
✅ How to Avoid It:
- Use ESE (Early Streamer Emission) LAs for large or open-area solar farms.
- For small systems, install conventional LAs at correct height and connect with low-resistance grounding.
Always install Surge Protection Devices (SPD) at ACDB, DCDB, and inverter terminals.
🔗 Mistake 3: Isolated or Improper Grounding Topology
🧲 Case Study: 150 Kwp Plant, Dhanbad
- Issue: Lightning surge damaged SCADA and ACDB.
- Reason: Isolated grounding of transformer and solar array.
- Root Cause: No GI strip interconnection between pits → potential difference caused internal surges.
✅ How to Avoid It:
- Follow parallel grounding practice:
- Interlink all pits using GI flat strip (40×6 mm or 25×6 mm).
- Create a closed loop around the plant for equipotential bonding.
Ensure transformers, inverters, and modules share a common ground plane.
🛰️ Mistake 4: Not Earthing Sensitive Electronics Like SCADA & Sensors
🛰️ Case Study: Multiple Rooftop Plants in Bokaro
- Problem: Erratic SCADA data, false alarms, unstable monitoring.
- Cause: Earthing was done only for inverters and structure, ignoring SCADA, combiner boxes, and sensors.
✅ How to Avoid It:
- Earth every signal-carrying or data-sensitive component:
- SCADA system
- Remote sensors
- Weather station
- Combiner boxes
- SCADA system
Use dedicated earth pits or SPD-based signal protection for communication and monitoring units.
🧑🔧 Mistake 5: Choosing Inexperienced or Untrained Installers
Even the best design will fail if the installer lacks technical understanding.
🚨 Common Errors by Untrained Installers:
- No earth resistance measurement after installation.
- GI strips loosely laid, exposed or broken.
- Lightning Arrestors without proper down conductor routing.
- Lack of documentation or marking of earth pits.
✅ How to Avoid It:
- Choose certified professionals or EPCs with:
- Experience in MW-scale solar grounding systems.
- Availability of earthing measurement tools (megger, clamp meter).
- Knowledge of IS/IEC standards for earthing and lightning protection.
- Experience in MW-scale solar grounding systems.
Ask for an “Earthing Layout Diagram” and test report after installation.
🌍 Earthing: Concepts and Best Practices:
Now that the importance of earthing in solar plants is clear, let’s explore the fundamentals of earthing and outline the best practices to ensure system safety, performance, and compliance.
🔌 What is Earthing?
Earthing is the process of transferring the immediate discharge of electrical energy directly to the earth using a low-resistance wire. In a solar power plant, earthing plays a critical role in protecting both equipment and personnel.
🎯 Purpose of Earthing in Solar Plants
- Safety: Prevents electrical shock hazards for maintenance personnel and users.
- Equipment Protection: Safeguards sensitive electronics like inverters from overvoltage and lightning.
- Voltage Stabilization: Maintains system voltage within a safe limit.
Lightning Protection: Provides a safe path for lightning strikes.
🔍 Components to Be Earthed in a Solar Plant
- Solar Panels (Module Frames) – to avoid leakage current risks.
- Mounting Structures – usually metallic and exposed.
- Inverter – the most sensitive equipment.
- AC and DC Distribution Boards
- Lightning Arresters and Surge Protection Devices (SPDs)
- Transformer (if used)
- Neutral of Power System
⚙️ How Earthing Impacts Solar Plant Performance
- Equipment Damage – due to voltage surges or lightning.
- Fire Hazards – caused by stray currents or short circuits.
- System Downtime – unplanned shutdowns due to tripping.
- Risk to Human Life – shocks or electrocution during maintenance.
- Loss of Warranty – many OEMs void warranties without proper grounding.
- Electrical Noise- Reduces electrical noise and improves
- signal integrity in communication cables.
- System Lifespan: Increases the lifespan of sensitive components.
- Safety Compliance: Ensures compliance with safety standards like IS 3043 or IEEE standards.
- Energy Losses: Helps avoid energy losses and inefficiencies due to leakage currents.
🛠️ Common Earthing Methods
1. Plate Earthing
- Uses a copper or GI plate buried vertically.
- Common in large plants.
- Pros: Durable, effective for higher fault currents.
2. Pipe Earthing
- Uses a GI or copper pipe with holes, buried vertically.
- Pros: Cost-effective, easy to install.
3. Chemical Earthing
- Uses chemical compounds to maintain soil resistivity.
- Pros: Ideal for rocky or dry soil, long life.
- Best for: Solar plants in difficult terrain or commercial setups.
4. Strip or Wire Earthing
- GI or copper strip used in trench, connected to grounding rods.
- Pros: Good for connecting multiple components.
⚙️ Beyond Basics: Best Practices for Earthing and Protection in Solar Plants
🔗 Paralleling Multiple Earthings in Large Solar Plants
In large solar plants, paralleling (interconnecting) multiple earth pits or earthing systems is a best practice that offers significant technical and safety benefits. Here’s why it’s recommended:
⚡ 1. Lower Earth Resistance
- Improved Dissipation: Parallel earthing paths reduce overall resistance to ground, ensuring better fault current flow.
- Reliable Performance: Even in poor soil conditions, interconnected pits maintain effective grounding.
🛡️ 2. Enhanced Safety
- Voltage Equalization: Prevents dangerous voltage differences between equipment during lightning or faults.
- Personnel Protection: Reduces risk of shock by keeping potential differences near zero across the plant.
🏗️ 3. System Redundancy
- Backup Paths: If one earthing fails, others carry the fault current—ensuring continuous protection.
- No Single Point of Failure: Maintains system integrity in case of ground damage or corrosion.
🌐 4. Uniform Earthing Potential Across Plant
- Interconnected Grid: Ensures all metal structures and equipment are at the same ground potential.
- Reduces EMI/RFI Issues: Essential for inverter and control system stability in high-voltage environments.
📈 5. Compliance with Standards
- Meets BIS, IEC & CEA Norms: Most standards recommend meshed or interconnected earthing for large installations.
- Required for Approvals: Mandated in many utility and government projects for commissioning.
🛠️ 6. Easier Maintenance & Monitoring
- Single Grounding Network: Simplifies measurement of earth resistance and fault diagnosis.
Accessible Testing Points: Enables periodic testing from multiple accessible locations.
⚡ Use GI Strip in Bigger Solar Plants
Galvanized Iron (GI) strips play a crucial role in the earthing system of large solar plants. Below are the key reasons for their recommendation:
🛡️ 1. Effective Grounding and Safety
- Low Resistance Path: Ensures safe dissipation of fault currents into the ground.
- Surge Protection: Shields inverters and modules from lightning and short-circuit surges.
🌧️ 2. Durability and Corrosion Resistance
- Galvanized Coating: Zinc layer protects against rust, ideal for outdoor exposure.
- Long-Term Reliability: Reduces maintenance in large installations.
🔌 3. Better Conductivity Across Large Areas
- Wider Surface Area: Enables efficient current flow compared to wires.
- Distributed Earthing: Easily laid across different zones of a large solar plant.
🧱 4. Mechanical Strength
- Robust Build: Resists physical damage better than copper or aluminum wires.
- Suitable for Harsh Conditions: Withstands environmental and operational wear.
💰 5. Cost-Effective for Large Installations
- Affordable: Lower cost than copper, yet effective for grounding.
- Balanced Performance: Offers good conductivity at a lower budget.
📜 6. Compliance with Industry Standards
- BIS/CEA Norms: Recommended by Indian regulatory standards for solar installations.
Trustworthy Choice: Accepted across major solar EPC and government projects.
🌿 Earthing has to be done as per site requirement:
- Higher resistance; requires multiple pits or use of chemical earthing.
- Deeper drilling and soil enhancement compounds may be needed.
Sandy or Dry Soil:
- Moisture-retaining compounds improve conductivity.
- More frequent maintenance and testing required.
Thunder-prone Areas:
- Prefer ESE-type arrestors with wider protection.
- Denser network of earth pits and surge protection devices recommended.
🏆 Best Practice Recommendation
For long-term safety and system reliability, the best method of earthing in solar plants involves a two-part approach:
✅ 1. Interconnection with GI Strip
- All key components — solar modules, inverters, ACDB/DCDB, transformers, and combiner boxes — must be interconnected using hot-dip galvanized (HDGI) flat strips (typically 25×6 mm or 40×6 mm).
- This creates an equipotential bonding grid, which prevents voltage differences between components during faults or surges.
✅ 2. Grounding with Copper-Bonded Chemical Earth Electrodes
- This interlinked network is then connected to earth pits constructed with copper-bonded electrodes and chemical backfill compound (BFC).
- These electrodes provide low-resistance and long-lasting earthing solutions, especially in rocky, dry, or sandy soils.
- Target earth resistance ≤ 1 ohm for sensitive electronic components.
🟢 This method ensures:
- Low and stable earth resistance
- Uniform potential across the system
- Long life and low maintenance
- Enhanced protection against surges and lightning strikes
Copper-bonded electrode with BFC = Provides reliable grounding to dissipate fault currents into the earth
This approach ensures both uniform potential across the installation and low-resistance discharge paths, which are critical for system safety and lightning protection.
🛡️ Precautions in Solar Plant Earthing
- Measure Earth Resistance regularly (should be <1 ohm ideally).
- Use separate earthing pits for AC and DC systems.
- Ensure equipotential bonding between metallic parts.
- Follow IS/IEC standards for installation.
- Use anti-corrosive backfill material for long-term performance.
Keep earthing pits labelled and marked with Earthing resistance with date of measurement.
📝 Final Thoughts on Earthing:
Earthing isn’t just a regulatory requirement—it’s the backbone of safety and performance in any solar power plant. Investing in proper earthing design and materials ensures long-term safety, uptime, and system efficiency.
