Lightning ProtectionTechniques For Roof-Top PV Systems

8/13/2019 Lightning ProtectionTechniques For Roof-Top PV Systems

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CHAPTER 1

INTRODUCTION

With increasingly complex and sophisticated buildings and equipment, a single

lightning stroke can result in physical damage and catastrophic failure. It can initiate fire,

cause major failures to electrical, telephone and computer services and simultaneously

cause substantial loss of revenue through down-time.

There are no devices or methods capable of modifying the natural weather

phenomena to the extent that they can prevent lightning discharges. Lightning flashes to,

or nearby, structures (or lines connected to the structures) are hazardous to people, to the

structures themselves, their contents and installations as well as to lines. This is why the

application of lightning protection measures is essential.

The lightning protection system is generally considered in two parts. The external

lightning protection system intercepts, conducts and dissipates the lightning flash to

earth. The internal lightning protection system prevents dangerous sparking within the

structure (using equipotential bonding or separation distance) [6].

The design of a lightning protection system needs to:

Intercept lightning flash (i.e. create a preferred point of strike)

Conduct the lightning current to earth

Dissipate current into the earth

Create an equipotential bond to prevent hazardous potential differences between LPS,

structure and internal elements/circuits

In achieving this, the lightning protection system must:

Not cause thermal or mechanical damage to the structure

Not cause sparking which may cause fire or explosion

Limit step and touch voltages to control the risk of injury to occupants

Limit damage to internal electrical and electronic systems

Dept. of EEE TEC, Vellarakkad1


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Lightning protection systems typically follow two approaches,

Non-isolated system where

potentially damaging voltage differentials

are limited by bonding the lightning

protection system to the structure

Isolated system where the

lightning protection system is isolated from

the structure by a specified separation

distance. This distance should be sufficient

that energy is contained on the LPS and

does not spark to the structure [6].

1.1 Step and touch voltages

Touch voltage is the voltage acting upon a person between his position on the earth

and the position of down conductor, when touching the down conductor. The current

path leads from the hand via the body to the feet.

Step voltage is a part of the earthing potential which can be bridged by a person

taking a step over 1m. The current path runs via the human body from one foot to the

other [7].

Fig. 1.1) Isolated and Non-Isolated protection

Fig. 1.2) Step and Touch voltage gradients



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1.2 Separation (isolation) distance requirements

A separation distance,

between the external LPS and

the structural metal parts is

essentially required. This will

minimize any chance of partial

lightening current being

introduced internally in the

structure. This can be achieved

by placing lightening conductors sufficiently far away from any conductive parts that

have routes leading into the structure. So, if the lightening discharge strikes the

lightening conductor, it cannot bridge the gap and flash over to the adjacent metal

work.

The separation distance between the item to be considered and the LPS (to ensure

that the dangerous sparking between them does not occur) is determined by the

following equation,

Fig. 1.3) Concept of separation distance

Fig. 1.4) Bonding & separation distance



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Where,

kiis a factor that depends upon the chosen lightning protection level.

kcis a factor that depends upon the number of down-conductors (note that a range is

given for 2 or more down-conductors, and depends on the current-sharing between

down-conductors).

kmis a factor that depends upon the electrical insulation material (1.0 for air, 0.5 for

concrete and bricks).

Lis the length in meter, along the air-termination or down conductor, from the point

being considered to the closest equipotential bonding point [1].

The values of ki, and kcare given in Tables 1.1 and 1.2.

Table 1.1) Values of ki

Table 1.2) Values of kc

1.3 Conclusion

At present, photo voltaic cells have a growing demand as a renewable energysource. For the roof-top installation, PV panels are integrated to the new buildings and

new constructions. This integration raise challenges in designing the building and also

the PV system. A major issue arises in this case is the lightning protection of the

building and PV system [1]. A single lightning stroke can damage the panels and cause

substantial loss of money. Hence, available protection techniques for safeguarding the

buildings against direct strikes are necessary to be evaluated to provide a safe location

to install the PV system.



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CHAPTER 2

EXTERNAL LPS

2.1 Introduction

External protection system of a building intercepts the direct lightning strikes by

air termination system, conducts the lightning current through a low impedance path to

the earth termination system, and disperses this high current to a low resistance earth.

In following the challenges in designing these three components are discussed [1].

2.2 Air termination system

The role of an air termination system is to capture the lightning discharge current

and dissipate it harmlessly to earth via the down conductor and earth termination

system. Therefore it is vitally important to use a correctly designed air termination

system [4]. The type of air termination system installed on the roof depends on the

shape and materials of the roof and usage of the building. Also, the type of protection

and the area which is critical to be protected influence the selection of air termination

system. Considering these factors, the following in any combination can be used for the

design of air termination,

Air rods (or finials) whether they are free standing masts or linked with conductors to

form a mesh on the roof.

Catenary (or suspended) conductors, whether they are supported by free standing masts

or linked with conductors to form a mesh on the roof.

Meshed conductor network that may lie in direct contact with the roof or be suspended

above it, so that the roof is not exposed to a direct lightening discharge.

Positioning of the air termination system is of paramount importance. The air

termination components should be installed on corners, exposed points and edges of the

structure [4]. Three basic methods recommended for determining the optimum location

of the air termination systems are,

The rolling sphere method (RSM)

The protection angle method (PAM)

The mesh method (MM)



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2.2.1 The Rolling Sphere Method

The rolling sphere method is a simple means of identifying areas of a structure that

need protection, taking into account the possibility of side strikes to the structure. In

this method, an imaginary sphere is rolled over the surface of the structure. Where the

sphere touches the structure, this point is vulnerable to a lightning flash and air-

termination(s) are required. The air-termination system is placed such that the sphere

only touches the air-terminations, and not the structure [4][6].

Corresponding to the class of LPS, radius of the rolling sphere is different.

For structures less than 60 m high the risk of flashes to the sides of the building is

low, and therefore protection is not required for the vertical sides directly below

protected areas.

Fig. 2.1) Rolling sphere method

Table 2.1) Rolling sphere radius and class of LPS

Fig. 2.2) RSM for buildings less than 60 m high



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In the IEC standards, for buildings above 60 m, protection is required to the sides of the

upper 20% of height.

This method is suitable for defining zones of protection for all types of structures

especially those of complex geometry [6].

Fig. 2.3) RSM for buildings greater than 60 m & less than 120m high.

Fig. 2.4) RSM for buildings greater than 120 m high



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2.2.2 The Protective Angle Method

The protective angle method is a mathematical simplification of the rolling sphere

method. The protective angle (a) is the angle created between the tip (A) of the vertical

rod and a line projected down to the surface on which the rod sits.

Air-terminations (rods/masts and catenary wires) are located so the volume defined

by the protection angle covers the structure to be protected. The height of the air-

termination is measured from the top of the air-termination to the surface to be

protected. The protective angle varies with the height of the air termination and the

class of the LPS. The protection angle method is limited in application to heights that

are equal to or less than the corresponding

rolling sphere radius [4][6].

The protection angle method can be used

on inclined surfaces, where the height of the

rod is the vertical height, but the protection

angle is referenced from a perpendicular line

from the surface to the tip of the rod [6].

Dept. of EEE TEC, Vellarakkad

Fig. 2.5) PAM for a single air rod

Fig. 2.6) Effect of height of the reference plane

on protection angle

Fig. 2.7) PAM applied to an inclined surface.

8


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Where the protection angle method alone is employed, multiple rods are generally

required for most structures. However the protection angle method is most commonly

used to supplement the mesh method, providing protection to items protruding from the

plane surface.

2.2.3 The Mesh Method

For protection of a plane (flat) surface, the mesh method is considered to protect

the whole bound surface if meshed conductors are:

Positioned on the edges (perimeter) of the surface

The mesh size is in accordance with Table 2.2

No metallic structures protrude outside the volume (consider air-terminals and

RSM/PAM method to protect these)

Fig. 2.8) Combination protection

Table 2.2) Mesh size for mesh method



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From each point, at least two separate paths exist to ground (i.e. no dead ends), and

these paths follow the most direct routes

The mesh method should not be used on curved surfaces, but can be used on non-

horizontal plane surfaces and compound surfaces [6]. For example on the vertical sides

of tall buildings, for protection against flashes to the side, or on compound surfaces

such as industrial roofs. For compound surfaces, conductors should be placed on the

roof ridge lines if the slope exceeds 1/10.

Fig. 2.9) Protection via mesh method

Fig. 2.10) Mesh method for compound shapes



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The protective area provided by the mesh method is the area bounded by the mesh.

The protection to areas adjacent to the mesh (e.g. building sides and lower structural

points) is determined by the protection angle method or rolling sphere method.

The protection provided by meshed conductors not placed in full accordance with

the mesh method, e.g., those raised above the building surface, should be determined

with an alternative design method, i.e., PAM or RSM, applied to the individual

conductors.

2.3 Down conductor system

The down conductor system is the electrically conductive connection between the

air termination system and the earth termination system. The function of down

conductor systems is to conduct the intercepted lightening current to the earth

termination system without intolerable temperature rises to damage the structure.It can

be implemented by separate conducting tapes/wires or natural components of the

building such as reinforcing rods of walls or concrete columns and steel structured

frames.

Fig. 2.11) Volume protected by meshed conductors according to PAM & RSM method



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To avoid damage caused during the lightening current discharge to the earth

termination system, the down conductor systems must be mounted to ensure that from

the point of strike to the earth,

Provide multiple paths for lightning current.

Be a direct continuation of the air-termination system.

The length of the current paths is kept as short as possible (straight, vertical, no loops).

Not be installed in gutters or down-spouts (even if PVC covered).

The connections to conductive components of the structure are made wherever required

(distance < s; s= separation distance).

Connect via a test joint to the earth termination network.

The general requirements for down-conductors on non- isolated LPS are:

At least two down-conductors should be used.

Down-conductors should be equally distributed around the perimeter of the structure

(within practical and aesthetic reasons).

Down-conductor should be located at exposed (external) corners of the structure where

possible (within 300 mm).

Attempt to locate down-conductors (using separation distance requirements) away from

doors, window frames, railings etc. that would be subjected to human touch during

thunderstorms periods.

The typical values of the distance between down conductors are shown in Table

2.3. In case of tall structures bonding all down conductors at regular vertical intervals

(say 20 m) may keep the system at equipotential [7].

Table 2.3) Typical spacing of down-conductors & equipotential bonding rings



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The general requirements for down-conductors in an isolated LPS are:

For rod air-terminations, one down-conductor is required per mast. If the mast is

metallic or interconnected reinforcing steel, then no additional down-conductor is

required.

For catenary air-terminations (one or more wires), at least one down-conductor is

required per support.

It should be noted that, down conductors must be installed straight and vertical,

and they should not be installed in loops or as over hangs. If loops cannot be avoided,

the separation distance across the gap must be greater than minimum separation, s.

2.4 Earth termination system

The surge current flowsthrough the down conductors will be dispersed to the soil

by the earth termination system. Since the reliable performance of the entire lightning

protection system is dependent upon an effective earthing system, it should possess the

following characteristics,

Low electrical resistance between the electrode and the earth. The lower the earth

electrode resistance the more likely the lightening current will choose to flow down that

path in preference to any other, allowing the current to be conducted safely to and

dissipated in the earth.The general requirement is that the lightning protection earthing

system must have a resistance of less than 10 ohms

Good corrosion resistance. The choice of material for the earth electrode and its

connections is of vital importance. It will be buried in soil for many years so has to be

totally dependable.

Design details are given on two methods:

Type A Vertical and/or horizontal electrodes installed outside the structure footprint.

Type B Ring electrode, installed outside the structure footprint (at a distance of about

1 meter from the structure walls. In a given ring conductor 80% of its length should be

in contact with soil) or natural earth electrode within footprint (e.g. footing

reinforcing).



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In type A system, there must be earth electrodes installed at the base of each down-

conductor. A minimum of two electrodes must be used.Depending on the class of the

LPS, the minimum total length of electrode at each down-conductor is, (l1) for

horizontal electrodes and (0.5l1) for vertical electrodes.

In type B system, a ring electrode around the perimeter of the structure, or natural

elements within the foundation is used.A ring conductor should have a mean radius of

distance re l1.

Fig. 2.13) Minimum length of electrodes, l1, for type A & B earthing systems

Dept. of EEE TEC, Vellarakkad

Fig. 2.12) Type A & B earthing systems

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Where the distance rewould require the ring to be installed at a distance greater

than 1 m from the structure, then it is recommended that the ring be installed at 1 m and

additional supplemental horizontal or vertical electrodes are added per the following

requirements. At least two equidistant supplemental electrodes should be installed and

ideally connected at the each point where the down-conductors connect to the ring

electrode.

Additional horizontal electrode lengthat each down-conductor = - re

Additional vertical electrode lengthat each down-conductor = ( - re) / 2

Type B is recommended for bare solid rock and for structures with extensive

electronic systems or great risk of fire. Type B is preferential from the point of view of

providing equipotential bonding between the down-conductors (assuming no ground

level equipotential ring is used) and providing better potential control in the vicinity of

conductive building walls. For structures with non-conducting walls (brickwork, wood,

etc.), and no interconnection to foundation reinforcing, a type B system or earth

equipotential bonding ring is highly recommended.

2.5 Conclusion

An external LPS consists of Air termination system, Down conductor system and

Earth termination system. These individual elements of an LPS should be connected

together using appropriate lightning protection components satisfying the lightning

protection standards. This will ensure that in the event of a lightning current discharge

to the structure, the correct design and choice of components will minimize any

potential damage.

Fig. 2.14) Type B earthing system with additional elements



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CHAPTER 3

INTERNAL LPS

3.1 Introduction

In the event of lightning, the danger of direct strikes to the protected building is

reduced by external lightning protection system, which facilitates the high inrush

current to flow through multiple down conductor system and then disperse to the soil

through the earth termination system. Apart from the direct strikes nearby strikes of

lightning can also affect the electrical systems inside the building. This is due to surges

that are generated by inductive coupling (rarely capacitive coupling as well).

3.2 Lightning protection zones

The protection of electrical and electronic systems in buildings and structures

against surges resulting from the lightening electromagnetic pulse (LEMP) is based on

the principle of Lightening Protection Zones. According to this principle, the building

or structure to be protected must be divided into internal Lightening Protection Zones

according to the level of threat posed by LEMP. The zones may not necessarily be

physical boundaries (e.g. structure walls). The zones are areas characterized according

to threat of direct or indirect lightning flashes and full or partial electromagnetic field.

The occurrence of lightning flashes, the lightning current or induced current and the

electromagnetic field are varied in these different LPZs [2][6][7].

LPZ 0 (Zero) is considered the lowest zone, LPZ 1, 2n being respectively

higher. In general the higher the number of zone the lower the electromagnetic

effects expected. It is the design and placement of the LPS that ensures the structureand internal contents are within an LPZ 0B zone.

Table 3.1) Lightning protection zones



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Internal systems are required be located within an LPZ 1 (or higher) zone. As seen

from Figure 3.1, electrical/electronic equipment located in LPZ 1 (or higher) and

connecting to external services such as power lines, data lines and water and gas pipes

(located in LPZ 0B or LPZ 0A) require transient protection devices (TPD) or Surge

Protective Device (SPD) and spatial shielding or shielding cables, to limit energy being

conducted from zones exposed to direct lightning or full/partial electromagnetic fields

or surge current. Non electrical services (e.g. water, gas, etc.) meet this requirement by

equipotential bonding [7].

At the boundary of each internal zone, the equipotential bonding must be carried

out for all metal components and utility lines entering the building or structure. This is

done directly or with suitable SPDs.

Fig. 3.1) Lightning protection zone concept



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3.3 Equipotential bonding

Equipotential bonding is simply the electrical interconnection of all appropriate

metallic installations/parts, such that in the event of lightening currents flowing, no

metallic part is at a different voltage potential with respect to one another. If the

metallic parts are essentially at the same potential then the risk of sparking or flashover

is nullified.

This electrical interconnection can be achieved by natural bonding or by using

specific bonding conductors. Bonding can also be accomplished by the use of Surge

Protective Devices (SPDs) where the direct connection with bonding conductors is not

suitable.

Figure 3.2 shows a typical example of an equipotential bonding arrangement. The

gas, water and central heating system are all bonded directly to the equipotential

bonding bar located inside but close to an outer wall near ground level. The power

cable is bonded via a suitable SPD, upstream from the electric meter, to the

equipotential bonding bar. This bonding bar should be located close to the Main

Distribution Board (MDB) and also closely connected to the earth termination system

with short length conductors [4][5].

Fig. 3.2) Example of main equipotential bonding



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In larger or extended structures several bonding bars may be required but they

should all be interconnected with each other. The screen of any antenna cable along

with any shielded power supply to electronic appliances being routed into the structure

should also be bonded at the equipotential bar [4].

3.4 Conclusion

The fundamental role of the internal LPS is to ensure the avoidance of dangerous

sparking occurring within the structure to be protected. This could be due to following

a lightning discharge, to lightning current flowing in the external LPS or indeed other

conductive parts of the structure and attempting to flash or spark over to internal

metallic installations. Carrying out appropriate equipotential bonding measures or

ensuring there is a sufficient electrical insulation distance between the metallic parts

can avoid dangerous sparking between different metallic parts.



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CHAPTER 4

LIGHTNING PROTECTION FOR ROOF-TOP PV SYSTEMS

4.1 Introduction

Building Integrated Photo Voltaic (BIPV) system as a type of implementation of solar

energy has a high demand at present. The assessment of risk of damage due to lightning for these

systems is necessary as the systems are installed at significantly large heights and extended

surface at such heights make these systems vulnerable to be intercepted with lightning stepped

leaders. Therefore, the external LPS ofBIPV systems must be designed by considering the PV

panel on the roof top as well.

4.2 Design of Lightning Protection System

To design suitable air termination system which is capable of protecting PV panels from

direct strikes and induced effects several extra precautions should be taken by the designer. The

roof should be protected considering the PV panel as an isolated system from the LPS. In this

case extra care should be taken regarding the shape, height, and total configuration of panels. In

addition, the separation distance of panels to the LPS is another specified issue. In designing the

air termination system which consists of rods on the flat surface roofs by the protection angle

method can be seen in Figure 4.1, the angle of the PV panels or the maximum angle of the

moving panels should be taken into consideration; the protected area by the rod must cover the

panel when the panel surface is rotated. In Figure 4.1, it can be observed that by the rolling

sphere method the distance between each two rods in a row, also the distance between the rods in

one row to the other row can be obtained. Further, in designing LPS, care should be taken to

minimize the shadow effect of finials on panels which may reduce the efficiency of system [1].

Fig. 4.1) Protection of PV panels applying RSM and PAM



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As shown in Figure 4.2, at least the minimum separation s should be kept between

LPS and the panels frame (isolated LPS). Separation s should also be kept between the

bonding conductor and PV panels mounting structure unless the LPS is bonded to the

frames (non-isolated LPS) to be protected. The requirement of an isolated or non-

isolated LPS depends on the sensitivity of the PV system for the stray lightning

currents that will be diverted into the metal framework of the panel. Depending on the

requirement of isolation or non-isolation of external LPS, other necessary components

of the LPS (such as SPD) may be determined.

An important aspect of external LPS in the presence of roof top PV system that has

not been properly addressed in the LP standards is the mechanical stability of the

vertical air-terminations. In the event of a mechanical failure of vertical air-termination

(such as the whole rod being enrooted from the base or part of the upper segment

detached from the main rod), the cost of damage may be highly enhanced if the fallen

part lands on the PV system [1]. Damage may be even worse in the case of mechanical

failure of early streamer emission (ESE) type air terminations (recommended in French

Standards NF C 17-102 and Spanish Standards UNE-21186) where a heavy metal part

is most often connected at the pinnacle of the rod. Authors have observed such damage

to the roof of buildings in several countries including India and Malaysia.

Fig. 4.2) Applying protection angle method for PV panels



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Hence, more stringent conditions should be introduced into the standards (or

guidelines) on the mechanical strength of vertical air-terminations of LPS for buildings

with roof top PV systems. These recommendations should cover the fixing strength of

the base plate, material strength, weight of the rod etc. On the other hand, mesh type

(horizontal tapes or wires) air-termination systems can strongly be recommended for

such structures instead of vertical metal rods. Such design will also reduce the shadow-

effect problem as well.

The selection of SPDs for roof-top PV systems depends on the class of LPS for

building and the isolation of PV panels frames from LPS, unless bonding the panel

frames to the LPS makes the system non-isolated which changes the SPD type

applicable for that PV system and sizes of earthing conductors that carry the lightning

induced currents. DC wires are used to connect the output of PV panels to the inverter

inside. Protection of DC wires in the LPZ1 is performed by SPDs that are connected

before the inverter in DC side. If the separation distance between panels on the roof and

inverter is more than 10 m, two sets of SPDs are required, one close to the PV modules

and another one close to the inverter. Furthermore, one set of SPD is essential in the

AC side. Also, if the distance between the inverter and load center is more than 10 m,

one SPD is needed in the load center as well [1]. Figure 4.3 shows a roof top PVsystem with all components, the internal and external LPS.

Fig. 4.3) SPD connection for roof top PV system



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The types of SPDs applicable for the PV system can be selected according to the

situation between the panels and LPS. For a roof-top PV system in a building without

the external LPS, two sets of SPD type 2 are needed in the DC side and two sets of

SPD type 2 in the AC side and load center (distance more than 10 m).

In the roof-top PV system with external LPS, if the distances between air

terminations and bonding conductors on the roof to the panels frame and mounting

system are more than the separation distance S, the PV system can be kept isolated, in

this case, two sets of SPD type 2 are required in the DC side and one SPD type 2 in the

AC side close to the inverter, but the SPD in the AC load center should be selected

from type 1.

For the non-isolated PV system where the LPS is connected to the panels frames

with a distance less than the separation distance S, two sets of SPDs type 2 are required

in the DC side, but in the AC side of inverter one SPD type 1 must be installed close to

the inverter and one SPD type 1 is also needed in the AC load center [1].

In order to reduce the dangerous sparking between the PV system components and

to make the PV system equipotentialized, all SPDs and inverter equipment grounding

must be bonded to the Equipotential bonding bar. This bonding bar should beconnected to the main earthing bar close to the earth termination system. Also the

panels frame must be connected directly to both the equipotential bonding bar and the

main earth bonding bar. The sizes of earthing conductors which connect the

components to the bonding bar are different depending on the volume of the induced

current that may be carried through the conductor. Also, different dimensions of

conductors are employed when the LPS is connected to the panel [1][7].

4.3 Conclusion

BIPV system is becoming an emerging trend in India. The PV panels are usually

placed in the roofs of tall buildings so the chance of lightning strikes is large. To

protect the panels, available protection techniques for safeguarding the buildings

against direct strikes are to be evaluated to provide a safe location to install the PV

system.



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CHAPTER 5

BIPV CASE STUDIES IN INDIA

5.1 Introduction

The solar PV technology involves direct conversion of available solar energy into

some useful electrical energy. It can realistically contribute to greater global

sustainability in the medium to long term. PV is becoming more and more accessible

both in urban and rural areas due to declining costs. Recently, there has been a world-

wide focus on the architectural integration of PV modules in the building envelope.

Such type of modules can effectively replace conventional building materials like roof

tiles, shingles, facades, and normal glazing. PV building materials can be manufactured

in a manner that they are quite similar to the conventional building products, blending

well with the surrounding environment.

5.2 BIPV systems in India

India with a tropical climate with sunny weather condition is a suitable area for

installing PV systems. Rabi Rashmi Abasan (meaning a solar housing complex) is

Indias first solar complex. This complex conceived by WBREDA (West Bengal

Renewable Energy Development Agency) is located at New Town Kolkata and is

spread over an area of 1.76 acres. There are 25 independent apartments in the complex,

each of which has been provided with a rooftop solar PV system of 2 KWP capacity.

Sixteen single crystal silicon modules of 125 WP have been put up in each case. Each

house owner within the complex willproduce his own power for domestic use and feed

any surplus power into the local grid. He can also draw power from the grid as and

when needed. The utility will pay the house owner and vice-versa on net monthly

metering.

Also great numbers of bungalows constructed in the country side provide

opportunities to install the rooftop PV systems. The preference of bungalows instead of

tall buildings normally with flat surface roofs are the lower height of the building and

slopped roof. By installing PV panels on the bungalows roofs, the danger of lightningstrikes shall be much less than tall apartments.



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Also the shading effects in most cases can be reduced because the panels are

mounted above a height that is taller than trees or any other equipment on the ground.

Furthermore, in the rooftop PV systems most of the wirings and all other equipments

except panels can be imbedded inside the building with the separation distance to the

LPS which can be protected against lightning [1].

Figure 5.1 and 5.2 show two BIPV projects in India, the slopped roof and the flat roof

respectively.

5.3 Conclusion

Two types of BIPV projects in India are slopped roof and flat roof projects. The

panels on the slopped roof are mounted directly on the roof without any mounting

structure while in flat surfaced roofs the panels are mounted on bars with certain height

fixed to structure; therefore, the height of the structure to be protected in the flat surface

is higher. Hence, in suchcases vertical type air-terminations become a must.

Fig. 5.1) Slopped roof BIPV system

Fig. 5.2) Flat roof BIPV system



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CHAPTER 6

CONCLUSION

An efficient design of the LPS with a well-located PV panel provides high

efficiency of power generation with minimized lightning risk. To design the external

LPS, the type of PV system and the configuration of PV panel should be taken into

account. The shape of the roof and location of the panel are also important factors in

optimizing the LPS. It is recommended to design the required LPS for the PV system

during the construction or pre-construction stage of the building, so that the efficiency

of the protection system could be maximized. Wherever it is possible, mesh type air

terminations are preferred over vertical rods to minimize mechanical damage in the

case of air-termination failure and also to avoid shadow effect.



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CHAPTER 7

REFERENCES

[1]Narjes Fallah, Chandima Gomes, Mohd Zainal Abidin Ab Kadir, Ghasem Nourirad,Mina Baojahmadi, and Rebaz j.Ahmed Lightning Protection Techniques for Roof-

Top PV Systems IEEE 7th International Power Engineering and Optimization

Conference (PEOCO2013), Langkawi, Malaysia June 2013.

[2]IEC 62305-1: Protection against lightning Part 1: General principles, 2010.[3]IEC 62305-2: Protection against lightning Part 2: Risk management, 2010.[4]IEC 62305-3: Protection against Lightning Part 3: Physical damage to structures

and life hazard, 2010.

[5]IEC 62305-4: Protection against lightning Part 4: Electrical and electronicsystems within structures, 2010.

[6] Erico international corporationERITECH-Lightning Protection Handbook Designingto the IEC 62305 Series of Lightning Protection Standards. , 2010

[7]DEHN Lightning protection guide revised 2nd edition., 2007

Documents

Lightning ProtectionTechniques For Roof-Top PV Systems