Furse Total Solution to Earthing & Lightning Protection

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TSC-0912 - 09.10.12
Furse, Wilford Road, Nottingham, NG2 1EB • Tel: +44 (0)115 964 3700 • Email: • Web:
Protecting photovoltaic systems
Photovoltaic (PV) systems are at risk from
transient overvoltages which may enter the
system following a direct lightning strike to a
structural LPS, or via the wider electrical
network.
Protection against transient overvoltages is achieved
through installation of appropriate SPDs on the DC
and AC side of the DC-AC inverter in the PV system.
Installation should follow the guidance provided in
Technical Specification DD CLC/TS 50539-12.
Installation on the DC side of the DC-AC inverter
An SPD specifically designed for use on the DC side of a
PV system should be installed.
Where the distance between the PV array and the
inverter is < 10 m, a single SPD suffices, mounted as
close as possible to the inverter. Where the distance
> 10 m, two SPDs should be installed, one close to the
inverter and the other close to the PV array. The
minimum Type of SPD is dependent on presence of
structural LPS/separation distance (see Table 4, below).
Note: Furse ESP PV Series SPDs (see pages 250-251)
offer combined Type 1+2 protection, and therefore
apply across all scenarios.
Installation on the AC side of the DC-AC inverter
The presence (or lack) of a structural LPS, plus whether
sufficient separation distance has been kept between
the LPS and the PV array, defines the SPD requirement
on the AC side of the inverter (see Table 4).
Where the distance between service entrance
(Main Distribution Board (MDB)) and inverter is
< 10 m, a single SPD should be installed at the
service entrance (MDB). Where > 10 m, two
SPDs should be installed, one at the MDB and
the other close to the inverter.
Furse Combined Type SPDs for AC mains
power circuits are applicable here. The SPD to
be installed will be dependent on the Class of
LPS around the structure, and the location of
the metallic services connected to it (i.e.
underground/exposed overhead supply).
Selection of the appropriate Furse SPD
therefore follows the product selection chart
shown on page 181.
SPD SPD
SPD for PV systems
(ESP DC550/12.5/PV or
ESP DC1000/12.5/PV)
AC
Output
Equipotential
bonding bar
DC
Input
kWh kWh
SPD
SPD for AC mains
power (Type 2)
SPD for AC mains power (Type 2)
LV Incomer
Earthing
conductor
Earth
termination
system
Meter/main
distribution
SPD SPD
SPD for PV systems
(ESP DC550/12.5/PV or
ESP DC1000/12.5/PV)
AC
Output
Equipotential
bonding bar
DC
Input
kWh kWh
SPD
SPD for AC mains power
(Type 2 - separation distance kept)
(Type 1 - separation distance
not kept)
SPD for AC
mains power
(Type 1)
LV Incomer
Earthing
conductor
External LPS
s
s = separation distance.This installation shows the separation distance is kept.Where the
separation distance is not kept, the PV array should be bonded directly to the external LPS.
Earth
termination
system
Meter/main
distribution
s
Generator junction box - SPD for
PV systems (ESP DC550/12.5/PV) SPD for AC mains
power (Combined
Type 1+2)
Operation building - SPD
for PV systems (ESP DC1000/12.5/PV)
PV units
LPZ 0
Figure 9: Roof
mounted PV
array, no
external LPS
Figure 10:
Roof mounted
PV array,
external LPS
Figure 11: Protection of solar park/PV array
PV arrays should
be protected by a
structural LPS
in line with
BS EN/IEC 62305.
Status of
structural LPS
SPD requirement Important note:
This page refers to
protection of PV power
circuits only. Ensure any
data/signal/telecoms lines
connected to the PV system
are also appropriately
protected.
Table 4: SPD requirement
according to structural LPS
configuration.
DC side, distance PV array to inverter
AC side of inverter
< 10 m > 10 m
No structural LPS
ESP PV Series protector
See pages 250-251
(min. Type 2 performance)
ESP PV Series protector
(min. Type 2 performance)
ESP AC mains power protector
See pages 182-195
(min. Type 2 performance)
Structural LPS (separation
distance kept)
ESP PV Series protector
(min. Type 2 performance)
ESP PV Series protector
(min. Type 2 performance)
ESP AC mains power protector
(min. Type 2 performance - inverter)
(min. Type 1 performance - MDB)
Structural LPS (separation
distance not kept)
ESP PV Series protector
(min. Type 1 performance)
ESP PV Series protector
(min. Type 1 performance)
ESP AC mains power protector
(min. Type 1 performance)