This entry provides an overview of common Solar PV system faults.
1. Types of PV System Faults
In recent years, the overwhelming growth of solar photovoltaics (PV) energy generation as an alternative to conventional fossil fuel generation has encouraged the search for efficient and more reliable operation and maintenance practices, since PV systems require constant maintenance for consistent generation efficiency. One option, explored recently, is artificial intelligence (AI) to replace conventional maintenance strategies. The growing importance of AI in various real-life applications, especially in solar PV applications, cannot be over-emphasized.
Over time, PV systems experience fault occurrences that affect the system’s operating efficiency, may cause damage to the system components, and may also lead to dangerous fire threats and safety hazards. PV system faults are classified as physical, environmental or electrical faults [1]. Panel faults, such as PV cell internal damages, cracks in panels, bypass diodes, degradation faults, and broken panels are classified as physical faults [1]. Shade faults due to bird dropping, dust accumulation, cloud movement, and tree shadows are classified as environmental faults [1]. Faults that are classified as electrical faults include MPPT faults, open-circuit faults, ground faults, line-line faults, short-circuit faults, arc faults, and islanding operation [1][2]. This section briefly discusses the different types of faults peculiar to PV systems.
2. Shading Faults
Shading occurs when objects, such as trees, neighboring buildings, and overhead power lines, cast shadows on PV modules
[3][4]. Shading in PV arrays could be homogeneous, where there is a balanced reduced irradiation across the PV panels or non-homogeneous, where there is an unbalanced reduced irradiation across the panels
[1].
3. Arc Faults
A frequent high-power discharge of electricity through an air gap between conductors causes this type of fault
[5][6][7]. The two forms of arc faults include first, the series arc faults that usually originate from solder separation, connection corrosion, cell damage, rodent damage or abrasion from numerous sources. Second, parallel arc faults that result from insulation failure in current-carrying conductors
[5][6].
4. Line-Line Faults
A line-line fault is an unintentional short-circuit between two points with differing voltage potentials
[8][9][10]. These faults are more difficult to detect than other faults and are frequently misinterpreted as short-circuit faults in grounded PV systems, since the fault current is determined by the voltage differential between two fault spots
[1]. The most common types of line-line faults are intra string faults, which are short-circuit faults between two locations on the same string, and cross string faults, which are short-circuit faults between two places on separate threads
[1].
5. Ground Faults
To protect users from a possible electric shock, it is common practice that the metallic parts of the PV array are grounded using earth-grounding conductors (EGC)
[1]. The term “ground fault” refers to any unintentional connection between a current-carrying conductor and an EGC that results in a current flow to the ground
[7][8][11][12].
6. Other Faults
This refers to any fault that cannot be categorized under any of the previously discussed faults. These types of faults include MPPT and inverter faults that mostly occur due to inverter components failure, such as IGBTs, capacitors, and converter switch failure
[13][14][15]; bypass diode faults resulting from a massive reverse current flow during faults, which leads to short-circuits
[16][17]; blocking diode faults, also as a result of a reverse current flow
[1]; open-circuit faults caused by items falling on PV panels, physical failure of panel-panel cables or joints, and sloppy termination of cables, plugging, and unplugging connectors at junction boxes
[18]; faulty connections damage of connecting cables or a wrong connection of panels
[19]; battery bank failures due to abnormal charging conditions
[1]; and blackouts caused by natural disasters, such as a storm and lightning
[20]. Most of these mentioned faults are usually due to an after effect of the other faults
[1].