GARD – Installation, Operation and Maintenance Manual
A l e n c o n S y s t e m s L L C - P a g e
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3 Introduction
3.1 PV Safety
As with any electrical appliance, solar panels can be at risk to certain electrical damages and
dangers, such as solar panel fires and power surges. Luckily, there are plenty of measures in
place to ensure safe PV operation. This document provides a brief on the safety issues often seen
on PV systems and Alencon’s preventive approach to safe operation through the Ground & Arc
Rapid Disconnect unit – the GARD.
3.2 Grounding
All bodies including equipment frames and people in contact with Earth are charged to Earth
(ground) potential. Therefore, touching grounded equipment frames is safe.
Electrical sources like solar panels or electrical batteries generate voltage or difference of electrical
potentials between two terminals. When the terminals are connected to a conductive load, the
current begins to flow from the source to the load thereby generating power.
Figure 4: Grounding schemes
A ground fault is an inadvertent contact between an energized conductor and ground or equipment
frame, thereby providing an alternative pathway for the current to
“leak”
to ground. The return
path of the fault current is through the grounding system and any personnel or equipment that
becomes part of that system. Ground faults are frequently the result of insulation breakdown -
damp, wet, and dusty environments expose the grounding system to degradation of insulation and
increase the potential for hazards to develop.
The common grounding schemes found in a PV system are –
Negatively Grounded PV
Positively Grounded PV
Ungrounded/Floating System
Either the positive or negative terminal of the source/load system can be connected to ground
potential. In this case the voltage on the second source terminal is referenced to ground or to the
equipment frame and defines the break down insulation strength.
