Isolated Lightning Protection for Solar Plant
PR Newswire: Solar power plants need isolated lightning protection because they are often located in exposed areas. In isolated lightning protection, the air terminal is mounted on a mast of a certain height to provide appropriate elevation as per the design and is placed away from the solar panel/panels to be protected. Solar lightning arrestors are typically installed on the roofs of buildings to provide a path for lightning strikes to be grounded. A lightning arrester kit includes a high-voltage terminal, a ground earthing terminal (rod), copper wires for connections and earthing chemicals.
Lightning is a visible electric discharge caused by a thunderstorm lightning that may occur within or between clouds between the cloud and air or between the cloud and the ground. Lightning is at its very core an electric current and discharged within a storm cloud within a storm particles of ice from at the highest parts of the storm.
The heavier and negatively charged particles then sink to the bottom of the storm and the lighter positively charged particles stay near the top as these particles interact a charge builds up and eventually overwhelms the insulating properties of the atmosphere. This is when lightning occurs within a cloud.
But what about on the ground cloud to ground lightning occurs?
when the strong negative charges at the bottom of the cloud attract positive charges on the ground. An electrical discharge called a step leader of negative charge will descend from the cloud seeking out a path of least resistance towards the ground. This actually happens so fast we can't see it with our naked eye when the negative charge gets close to the ground the positive charge on the ground will send a streamer upwards to meet the negative charge. The negative and positive channels connect and the discharge becomes what we know as a stroke of light.
how does a lightning arrester work?
A lightning arrester protects electrical equipment from high-voltage surges by diverting the surge to the ground, bypassing the equipment:
Types of Lightning Arrestors
There are two major types of Lightning protection systems: Active and Passive.
Franklin Rods
The Franklin rods (conventional arresters) we discussed earlier are part of the passive category.
These devices have one primary function: to intercept the lightning strike. Their protection is based on their position and composition. Since lightning tends to strike the highest points and charged objects, the probability of a strike hitting the Franklin rod is high.
The LA then collects these charges and earths them into the ground. A lightning rod with a height of 1 meter will extend its protection to approximately 5 meter radius.
ESE Lightning Arrestor
ESE stands for Early Streamer Emission, and it is a form of active lightning arrestor. Unlike the Franklin rod, ESE is a sum of many different electronic parts.
An ESE-type arrester contains within itself an ion generator. Sensing a change in the environment and the possibility of a potential strike, the device starts creating ions and throwing a stream into the air. As a result, it attracts lightning, before safely grounding the charges.
ESE can be installed anywhere between 4-30 meters above ground, and are ideal for commercial solar installations. Moreover, you can find ESE lightning arrestors with 4 levels of protection in the market, each covering a higher area.
Typically, an ESE installed at a height of 5 meters can cover between 79 meters (level 1) to 107 meters (level 4).
Advantages of ESE type Lightning Arrester over Traditional Arrester
ESE-type lightning arresters are considered better than conventional devices. Here’s why:
1. Bigger Radius of Protection
The radius of protection refers to the circular area where lightning does not strike due to the presence of equipment like a lightning arrester in the middle. ESE has a bigger radius of protection as compared to the conventional LA.
Moreover, ESE not only protects the solar power plant but also the surrounding areas from lightning.
2. Early Action
ESE possesses the capability to detect the potential occurrence of lightning well in advance of it striking an object. As a result, it has a lower response time as compared to conventional devices. Furthermore, it can intercept lightning from considerable distances, making it more efficient.
3. Cost-effective
In the case of a large-scale installation generating megawatts of power, safeguarding the entire area would require multiple lightning rods. In this context, investing in an ESE-type arrester proves to be more cost-effective, as a single device can cover a larger area.
Lightning Protection for Solar Plant
Solar power plants need isolated lightning protection because they are often located in exposed areas. Solar lightning arrestors are typically installed on the roofs of buildings to provide a path for lightning strikes to be grounded. A lightning arrester kit includes a high-voltage terminal, a ground earthing terminal (rod), copper wires for connections and earthing chemicals.
- Large surface area: Solar power plants are often large and have a large surface area, making them a target for lightning.
- Metallic build: Solar power plants are often made of metal, which attracts lightning.
- Isolated locations: Solar power plants are often located in isolated areas.
- High rates of lightning strikes: Some areas are more prone to lightning strikes than others.
- Damage to sensitive equipment: Lightning can damage the sensitive equipment in solar power plants.
- Separating the lightning conductor: The lightning conductor should be separated from the conductive parts of the solar power plant.
- Ensuring a safety distance: A sufficient safety distance should be maintained to prevent flashovers during a lightning strike.
- Using an air termination system: An air termination system intercepts lightning strikes
- Using a down conductor system: A down conductor system provides a dedicated path for lightning.
- Using an earthing system: An earthing system dissipates the lightning current into the earth.
- Using a surge protection device: A surge protection device protects the solar panels from damage caused by lightning strikes.
A lightning arrester protects electrical systems from lightning by diverting a lightning surge's current to the ground, away from sensitive equipment:
Lightning is caused by the buildup of opposite charges in the atmosphere, which eventually breaks down the insulating capacity of the air. The resulting rapid discharge of electricity is what we see as lightning.
Lightning strike is one of the biggest fears of consumers when it comes to solar. And why wouldn’t it be? A single lightning bolt can generate 300 million Volts and have a current strength of 30,000 Amps! That’s more than enough to damage the system and property.
So, let’s dive into the world of LA and its workings and understand why an ESE-type LA is better than conventional devices.
Nowadays more such solar farms are being protected by the Early Streamer Emission technology-based Lightning Protection System as per standard for Protection against lightning strikes and installed away from these panels to be protected which avoids shadow issues on solar panels.
LA arrangement and the solar panel should be maintained. The separation distance can be calculated based on the following parameters.
- Height of the supporting mast.
- Latitude and Longitude of the site.
- Time of operation and
- Seasonal variation
When calculating lightning arrester placement for a solar power plant, you can consider the following factors:
Separation distance
The distance between the solar panel and the lightning protection system (LPS) should be calculated based on the height of the supporting mast, the site's latitude and longitude, the time of operation, and seasonal variation.
Shadow
The shadow of the lightning arrester arrangement can affect the performance of the solar system, so it's important to maintain a safe separation distance.
Down conductor
The down conductor should be at least two runs from the air terminal and connected to at least two earth electrodes per down conductor.
Arrester rating
The arrester's rating should be at least 1.2 times the transformer's rating.
You can also assess the current status of the system's earthing and protection against transient overvoltage to determine if the safety level is sufficient.
Ese Lightning Conductor Protection Radius Calculation
Protection Radius Table
ASLA - Axis Early Streamer Emission Lightning Arrester
| ESE conductors | h=Conductors tip height (m) | |||
|---|---|---|---|---|
| 2 | 3 | 4 | 5 | |
| Level-1 | ||||
| C20 | 20 | 30 | 40 | 50 |
| C40 | 24 | 35 | 47 | 58 |
| C60 | 32 | 49 | 66 | 82 |
| Level-2 | ||||
| C25 | 23 | 37 | 45 | 56 |
| C40 | 26 | 39 | 52 | 65 |
| C60 | 36 | 54 | 72 | 90 |
| Level-3 | ||||
| C25 | 26 | 39 | 52 | 65 |
| C40 | 30 | 45 | 60 | 75 |
| C60 | 40 | 60 | 80 | 100 |
| Level-4 | ||||
| C25 | 29 | 43 | 58 | 72 |
| C40 | 34 | 50 | 67 | 84 |
| C60 | 44 | 66 | 88 | 110 |
Here are the protection levels for lightning arrestors:
-
Level IThe maximum surge current is 200 kA, and the protection radius is 20 meters. This level is used for large areas, such as explosive material complexes and petrochemical facilities. The worst-case scenario of a direct lightning strike, with a peak pulse of 200 kA.
-
Level IIThe maximum surge current is 150 kA, and the protection radius is 30 meters. This level is used for multiple areas, such as hospitals, warehouses, and telecom towers. The peak pulse is 150 kA, with half of that flowing into the earth connection.
-
Level IIIThe maximum surge current is 100 kA, and the protection radius is 45 meters. Covers 80% of applications, including houses, office complexes, and industrial plants.
-
Level IVThe protection radius is 60 meters.
To reduce the susceptibility of a solar power system to surges, the "twisted pair" technique can be used. This technique equalizes and cancels out any induced voltages between two or more conductors.
What is the coverage area of a lightning arrester?
The coverage area is the area within which the arrestor can protect a structure from lightning strikes. This semi-circle area is calculated by considering the radius of protection which is calculated based on the following parameters
- the height of the lightning arrestor
- the level of protection decided during risk assessment
- the type of arrestor - like ASLA 15, 30 and 60
This Delta value is the constant value for different ESC models given by the ESC manufacturer based on the lightning strike carrying capacity of the arrestor.
Example:
Height of arrestor is 5 meter
you are selecting a protection level of 4, which means the value of R will be 16 meters
and you are selecting the aslas 60 ESC model, your Delta value will be 63 meters
Now put them into the formula,
This means that all objects within the radius of 110 meters of your lightning arrestor are protected from direct lightning strikes.
We have done all the hard work of calculating this formula for various configurations.
Just follow this table to know the radius of protection for your structure
Let's use the same values as the example above using in the above table
Say the height of your arrestor is 5 meters and you are aiming for protection level of 4 for last 60 model, see table, you get the coverage area as 110 meters.
As per NFC 17-102, the ΔT for an ESE Lightning rrester should be at least 10μs – this means that the emission time of the ASLA ESE is at least 10μs. ASLA ESE products ranges from a ΔT of 10μs to 60μs, depending on the requirements of the project.
Active Lightning Protection Solution with High End ratings of protection radius 107m at 5m height, ΔT 60μsec
Example of Delta value of different manufacturer:
The calculation for the radius of protection
it is calculated with the below formula:
Where,
Rp (h) (m) is the protection radius at a given height h
h (m) is the height of the ESEAT tip over the horizontal plane through the furthest point of the object to be protected
r (m) is 20 m for protection level I | 30m for protection level II | 45m for protection level III | 60m for protection level IV
∆ (m) ∆ = ∆T x 106 Field experience has proved that ∆ is equal to the efficiency obtained during the ESEAT evaluation tests ∆ is the speed of ion meter per micro second - Triggering time
Rp = √(h(2D-h) )+ ∆L(2D+ΔL) h ≥5m.
ΔL = V × ΔT
Rp: Conductor protection area radius
h : The distance between the point of conductor and the area to be protected
ΔT: Triggering time
D : Triggering distance according to the NF C 17-102 standard
D value is: D= 20 Level-1
D= 30 Level-2
D= 45 Level-3
D= 60 Level-4
ΔL(m) = v (m/ µs). ΔT(m/µs)
About Relevant Regulation
• Due to the negligible effect on the increase of probability of a direct lightning strike to PV generators on a building, it does not necessarily require a lightning protection system if none is already present
• In case the physical characteristics or prominence of the building do change significantly, it is recommended to carry out a risk assessment according to IEC 62305-2 standards, and if required, install a lightning protection system according to IEC 62305-3.
• If there is a lightning protection system (LPS) already installed, the PV generator should be integrated into the LPS according to IEC 62305-3.
• Even if there is no LPS installed, overvoltage protection may still be required to protect the PV generator and the power conversion unit.
Distance between a lightning arrester
The minimum distance between a lightning arrester and solar panels in a solar power plant is 0.5 meters. However, the exact distance depends on several factors, including:
- The type of lightning arrester
- The voltage level of the system
- The installation requirements of relevant standards and regulations
Lightning Protection Earthing
Enter the lightning arrestor, a key ally in the earthing arsenal. Lightning protection earthing is specifically designed to protect solar plants from the high voltage spikes caused by lightning strikes. This type of grounding diverts the potentially destructive energy directly into the earth, thereby protecting the sensitive electronic components of your solar plant.
Here are some things to consider when calculating earthing for a lightning arrester at a solar power plant:
Product standards
IEC 62561-1 (EN 62561-1): Lightning protection system components (LPSC) – Requirements for connection components. This standard describes test procedures for metal connection components. Components falling within the scope of this standard.
IEC 62561-2 (EN 62561-2): Lightning protection system components (LPSC) – Requirements for conductors and earth electrodes. This standard specifies the requirements on conductors, airtermination rods, earth lead-in rods and earth electrodes.
IEC 62561-3 (EN 62561-3): Lightning protection system components (LPSC) – Requirements for isolating spark gaps (ISG)
IEC 62561-4 (EN 62561-4): Lightning protection system components (LPSC) – Requirements for conductor fasteners
IEC 62561-5 (EN 62561-5): Lightning protection system components (LPSC) – Requirements for earth electrode inspection housings and earth electrode seals
IEC 62561-6 (EN 62561-6): Lightning protection system components (LPSC) – Requirements for lightning strike counters (LSC)
IEC 62561-7 (EN 62561-7): Lightning protection system components (LPSC) – Requirements for earthing enhancing compounds
IEC 61643-11 (EN 61643-11): Surge protective devices connected to low-voltage power systems – Requirements and test methods
IEC 61643-12 (CLC/TS 61643-12): Surge protective devices connected to low-voltage power distribution systems – Selection and application principles
Renewable Energy: Report covers installed capacity & forecasts for renewable energy market to promote and disseminate knowledge of all the various topics and technologies of different renewable energy resources on green and sustainable business,.
