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Figure 27. PV system protection
Leave Floating
Figure 28. Array Frame earthing decision tree
• Class II modules?
Yes
• Class Il Cables, connectors/ions & Junction Boxes
•Isolation Transformer in Inverter?
(Note: to BS 3535 between a.c. & d.c.)
• In Equipotential Zone?
(Note: freestanding ground mounted, or building roof
mounted arrays (away from building metalwork) will
normally not be within the equipotential zone. However, a
solar thermal system, or other building linked metalwork,
installed within reach may extend the equipotential zone
outside the normal building envelope)
• PME Earthing?
Install & bond to earth spike
(Note: do not take PME out of
equipotential Zone)
(Note: Use 10mm² braid or equiv)
(Note: If an earth spike is already Installed for Lightning Protection, bond to this braid)
(Note: Use 10mm² braid or equiv)
4. PV SYSTEM PROTECTION
In order to prevent damage to the system due to over currents (overload
or short circuits) that might occur during use, measures for adequate
protection should be taken.
4.1.
Protection against lightening
PV systems do not increase the building's risk of being hit by lightning.
Any earthing arrangements must be in accordance with BS-7430,
BS-6651, BS-7671.
If there is already a lightening protection system (LPS) in the building the
PV generator must be connected to it. The internal protection circuit of
the PV should be carefully implemented.
Exceptions can be made to photovoltaic systems that are situated in ex-
posed locations, which should have a proper separate protection system
against lightening.
If the building does not have an LPS the PV support structure should be
connected to earth, and incorporated in equipotential bonding according
to the figure 27.
4.1.1.
Array Frame Earthing Decision Tree
The kits are composed with class II modules, class II DC cables & con-
nectors and are connected to the mains via an inverter with an isolation
transformer. This approach is recommended and permits the array frame
to be left floating.
(Figure 28)
and
and
No
No
Yes
Bond direct to Consumer
Earthing Terminal
(Note: Use 10mm² braid or equiv)
Yes
19
Solargen solar PV
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