Solar power plants are increasingly deployed across India. With large metal structures, panels, and exposed rooftops, they are extremely vulnerable to lightning strikes.
- What many owners don’t realize is Lightning damage is often NOT covered under EPC warranties or operational insurance policies.
- A single lightning strike can damage inverters, panels, and communication systems — leading to heavy financial loss and downtimes.
Proper lightning protection is not just compliance — it is mission-critical. This makes proper Lightning Protection Systems (LPS) not just a best practice, but an essential investment to secure long-term plant performance and financial viability.
⚠️ Why Lightning Damage is NOT Covered by Warranty or Insurance
❌ EPC Warranty Exclusion
EPC contractors generally treat lightning as a Force Majeure (Act of God). Therefore:
- Warranty does not apply to damage caused by lightning or surges unless the system was improperly installed.
- Even equipment manufacturers exclude lightning-induced failures unless proven the product was inherently defective.
❌ Operational Insurance Limitations
Standard plant insurance may exclude damages caused by electrical surges, especially:
- If proper Lightning Arrestors (LAs) and Surge Protection Devices (SPDs) were not installed.
- If poor earthing or maintenance was recorded.
🔐 What This Means for Plant Owners
The financial responsibility of lightning damage lies with the plant owner unless:
- Proper protection is installed and maintained.
- Optional natural disaster coverage is added to insurance.
🌪️ 5 Common Mistakes in Lightning Protection
❌ Mistake 1: Inadequate Lightning Arrestor Installation
🔍 Case Study – Rooftop Solar Plant, Ranchi (2021):
⚠️ Issue:
A lightning strike hit near a 100 kWp rooftop solar plant.
The site had no or inadequate lightning arrestor (LA) system, leaving critical components exposed.
💥 Impact:
- 🔧 Inverters severely damaged
- 💸 Repair Costs: ₹4+ lakhs
- ⏱️ Downtime: Significant interruption in plant operation
🔍 Root Cause:
- ❌ Insufficient Lightning Arrestor (LA)
- ⚡ Lack of complete coverage over the rooftop installation
✅ Solution:
- Install a well-designed Lightning Arrestor system with full-area coverage
- Ensure protection even for small rooftop systems
- Prevent costly equipment failures with proper surge and lightning protection
❌ Mistake 2: Using Conventional LA in High-Risk Zones Without ESE
🔍 Case Study – Ground-Mounted Plant, W.Bengal (2022):
⚠️ Issue:
A nearby lightning strike caused surge induction in the AC line.
The plant was protected only with conventional rod-type arrestors, which lacked adequate coverage.
💥 Impact:
- 🔧 3 inverters damaged beyond repair
- ⏱️ Downtime: 7 days
- 💸 Financial Loss: ₹4.5 lakhs
🔍 Root Cause:
- ❌ Absence of Early Streamer Emission (ESE) arrestor
- ⚡ Improper earthing of existing lightning arrestors
✅ Solution :
- Install an ESE-type Lightning Arrestor for wider and more effective coverage
- Ensure proper earthing of all protection devices
- Regularly audit and test the lightning protection system for reliability
❌ Mistake 3: EMI Issues in String Monitoring Units (SMUs)
🔍 Case Study– Rooftop Industrial Plant, Dhanbad:
⚠️ Issue:
Frequent communication errors and data loss were observed from SMUs, affecting system monitoring and performance analysis.
💥 Impact:
- 📉 Unreliable generation data
- 🚨 False alarms and failure in remote diagnostics
- 🔄 Disruption in plant performance assessment
🔍 Root Cause:
- ❌ No equipotential bonding
- ⚡ Improper placement of Lightning Arrestors (LAs)
- 🛡️ Absence of shielding against electromagnetic interference (EMI) from lightning-induced surges
✅ Solution :
- Ensure proper equipotential bonding across all SMUs
- Install and position LAs effectively based on surge risk zones
- Implement shielding and grounding practices to mitigate EMI disturbances
❌ Mistake 4: Low Height of Lightning Arrestors
🔍 Case Study – School Rooftop Solar Plant, Jamshedpur
⚠️ Issue:
A conventional Lightning Arrestor was installed below the height of the solar panels.
As a result, it failed to intercept lightning strikes, leading to hotspot formation and damage in multiple panels.
💥 Impact:
- 🔥 Panel hotspot failures
- ⚠️ Increased risk of fire and long-term panel degradation
- 🛠️ Costly maintenance and performance loss
🔍 Root Cause:
- ❌ Lightning Arrestor installed below panel level
- 📐 Incorrect height and protection angle ignored
✅ Solution :
- Install LAs at least 2 meters above the highest point of the plant
- Maintain a 45° protection angle to ensure full coverage of the installation
- Follow standard LA installation norms for effective lightning protection
❌ Mistake 5: LA Not Bonded with SPDs and Earthing Network
🔍 Case Study – Commercial Building, Purulia:
⚠️ Issue:
Lightning strike caused a surge via communication cable (SCADA not surge-protected).
💥 Impact:
- ACDB( Alternating Current Distribution Board), Control panel and SCADA (Supervisory Control and Data Acquisition) damaged
- Monitoring offline for 10 days
- Loss of remote visibility and alarms
🔍 Root Cause:
Lack of surge protection on data lines and no proper equipotential bonding.
🧑🔧 Importance of Installer in Lightning Arrestor in Solar Plants
Proper installation of a Lightning Arrestor (LA) is as critical as choosing the right type of device. Even the most advanced ESE arrestor or surge protection system can fail to protect if not correctly designed, positioned, and earthed. That’s where the installer’s expertise becomes vital.
🔧 1. Correct Positioning & Height Calculation
The LA must be installed above the tallest point of the plant, ensuring a clear protection radius.
A trained installer uses IS/IEC 62305 guidelines to calculate the zone of protection, considering strike probability and layout.
Poor placement can leave parts of the plant exposed — defeating the entire purpose of the LA.
🌍 2. Accurate Risk Assessment
Experienced installers assess lightning risk based on:
Geographic zone
Surrounding topography
Size and layout of the solar plant
This influences whether a conventional or ESE arrestor should be used.
⚙️ 3. Proper Earthing System Integration
The LA must be connected to a low-resistance earthing system (typically <5 ohms).
Skilled installers ensure:
Use of copper bonded rods
Adequate conductor size (e.g., 25×3 mm GI strip or copper)
Chemical earthing to maintain long-term performance
⚡ 4. SPD and Ground Bonding
Lightning protection doesn’t stop at the LA. Installers must:
Install Surge Protection Devices (SPDs) at key points (DC & AC sides, SCADA)
Ensure all metal bodies and panels are bonded to the same earthing grid
Avoid ground loops and floating potentials
🧾 5. Compliance, Testing & Documentation
Certified installers:
Conduct earthing resistance tests
Submit as-built drawings and test reports
Ensure compliance with CEA & IEC standards
🛡️ Why it Matters:
Improper installation by untrained personnel can lead to:
⚠️ Inverter damage despite LA
⚠️ No insurance claims due to non-compliance
⚠️ Safety hazards or fire risk
📘 Basic Understanding of Lightning Arrestor
🌩️ What is a Lightning Arrestor?
📌 Definition
A Lightning Arrestor (LA) is a device designed to protect electrical equipment by diverting high-voltage surges from lightning to the ground.
🎯 Purpose
- Protect solar panels, inverters, SCADA, and control equipment.
- Prevent fire hazards.
- Avoid revenue loss due to breakdown.
- Protects human life and costly infrastructure
⚙️ How Does a Lightning Arrestor Work?
🧪 Technical Working:
- Normal Condition: The arrestor remains non-conductive under normal voltage conditions.
- During a Surge: When a lightning-induced voltage spike occurs, the arrestor offers a low-resistance path to the surge, directing it safely into the ground, bypassing sensitive equipment.
- Post Surge: After the surge passes, the arrestor returns to a high-resistance state, ready for the next event.
This process happens in microseconds, protecting sensitive components like inverters and controllers.
🧰 Types of Lightning Arrestors
There are two common types of lightning arrestors used in modern infrastructure:
🏗️ 1. Conventional Lightning Arrestor
🔍 Description:
- Consists of a Franklin Rod (air terminal), a down conductor, and earthing system.
- Works by offering a pointed metallic path to intercept lightning and direct it safely to earth.
- Installed at the highest point.
- Covers limited area (radius ~45° cone of protection).
✅ Advantages:
- Time-tested, simple design
- Low cost
- Passive system, no power consumption
🏭 Applications:
- Small to medium industrial structures
- Low-rise buildings and compact solar arrays
⚡ 2. ESE (Early Streamer Emission) Lightning Arrestor
🔍 Description:
- Advanced design with ionizing head having an active air terminal that emits early streamers to capture lightning at a greater distance.
- Offers wider protection radius compared to conventional systems (up to 100 meters).
- Creates an upward streamer before natural initiation.
✅ Advantages:
- Covers larger area with a single unit
- Faster and earlier activation
- Ideal for solar farms, telecom towers, and high-rise structures
🏭 Applications:
- Large-scale solar plants
- Airports, refineries, and telecom infrastructure
📊 Comparative Table: Conventional vs. ESE Lightning Arrestor
| 🔍 Feature | 🛠️ Conventional Lightning Arrestor | 🚀 ESE (Early Streamer Emission) Lightning Arrestor |
|---|---|---|
| ⚙️ Technology | Simple metallic rod (passive system) | Advanced ionization-based (active system) |
| 📏 Protection Radius | Small (typically 20–30 meters) | Large (up to 100 meters radius) |
| ⚡ Trigger Mechanism | Relies on natural downward leader | Triggers early upward streamer before lightning connects |
| 🏗️ Structure Height Required | Must be installed significantly above protected structure | Can be installed with minimal elevation, yet protects larger zones |
| 🧭 Coverage Area | Limited to vertical cone (~45° protection angle) | Circular umbrella-like area, ideal for large solar fields |
| 🔌 Best Application | Small rooftop solar, compact zones | Large ground-mount, industrial, utility-scale solar plants |
| 💰 Cost | Lower initial cost | Higher initial cost, but better ROI for large area |
| 🛡️ Level of Protection | Basic protection from direct strikes | Advanced protection even in high lightning density areas |
| 🧰 Maintenance | Very low maintenance | Needs annual inspection of emission head |
| 🌟 Advantage Summary | ✔️ Simple to install ✔️ Cost-effective for small sites | ✔️ Covers wider area ✔️ High efficiency in strike interception |
✅ Best Practices for Lightning Protection in Solar Plants
1. Risk Assessment First
Conduct lightning risk assessment based on IEC 62305 or IS/IEC 62305-2.
2. Choose LA Type Based on Project Size & Location
- Rooftop < 100 kWp → Conventional LA.
- Ground-mounted or > 100 kWp → Prefer ESE LA.
3. Integrate SPD on AC & DC Side
Use Class B+C SPD on input and output of inverters, ACDB, and SCADA.
4. Use Proper Earthing
- Chemical earthing with copper bonded rods.
- Resistance < 5 ohms.
- Equipotential bonding of all components.
5. Annual Inspection & Testing
- Measure ground resistance.
- Inspect rods and connections.
- Replace damaged or corroded parts.
Lightning protection is a critical infrastructure for solar plants. A well-designed system using the right type of arrestor, properly grounded and integrated with SPDs, ensures safety, reduces downtime, and protects investment. Avoiding common mistakes and following best practices is not just a matter of compliance — it’s about ensuring long-term performance and reliability of your solar assets.
