Ground faults are a rather typical sort of problem in PV systems, but the harm to the inverter installations can also be more catastrophic. The source of this extremely unwanted current flow is an unintended electrical connection between the current-carrying wire in the photovoltaic array and the equipment grounding conductor. As a result, it is critical to eradicate the defect in a timely manner in order to return the system to working order. Ground faults, in addition to being a safety risk, also pose a fire risk because short-circuited electricity heats exposed metal. Furthermore, inadequately recognized and curtailed ground faults might pose a risk of fire in solar PV arrays. In this post, we will look at ground faults in solar panels using a solar farm case study here, as well as practical methods for detecting such flaws.
- What Are The Dangers Of Solar Panel Ground Faults?
Ground faults are especially problematic in bigger solar PV systems since they may go unnoticed for long periods of time. Ground fault protection systems do not detect the modest (1 amp) current flowing in a ground fault, resulting in a blind zone. The first DC ground fault becomes a parallel channel for a huge current in the case of a subsequent fault with higher electricity in which the GFP could trip the circuitry. This can quickly escalate into a huge fire. While the GFP may remove the secondary ground fault, large currents might return via the initial undiscovered ground fault, rapidly disintegrating the insulation and creating a fire.
- Common Causes For Ground Faults On A Solar Panel
One of the most common failures in solar panel PV systems is a ground fault, which can be triggered by one of the following factors:
- Cable insulation failure is caused by rodents nibbling through the insulating envelope and inducing a ground fault.
- Grounding errors within solar panels may occur when a solar cell short circuits to grounded module chassis owing to poor encapsulation, physical damage, or moisture degradation in the solar module.
- An ancillary short circuit around an ordinary conductor and ground, such as a wire in a solar panel accidentally hitting a grounded conductor.
- Detection Of A Ground Fault On A Solar Panel
Detecting a solar panel ground fault can be challenging, especially in big PV systems. This is because such ground faults are frequently far less than the threshold sensitivity of a ground fault protection device. Residual current detectors and insulation resistance monitoring are two methods for diagnosing DC ground faults. It is recommended that a grounding test utilizing an insulation resistance tester be performed on a regular basis to assess the resistance to ground when the grid is in an open circuit setup. The evaluation can disclose two possibilities: the insulation resistance reflects above the threshold and the system may commence, or the insulation resistance struggles beneath the threshold, indicating defective insulation and the possibility of a ground fault.
Even if the inverter’s ground fault detection interrupter (GFDI) reliably breaks the circuit, determining the cause of the ground fault might be challenging. Initially, technicians should use a continuity test to see if the GFDI is ruptured. To do a continuity test, place the leads of a multimeter on the metal tip of a fuse and set the selector to resistance. If the resistance is extremely high, the fuse may have melted and should be replaced. Following that, technicians should use an insulation tester to measure the conductors’ insulation resistance. A voltage is given to the conductors in this test, causing a current to flow through the wire, and is measured to assess the status of the insulating resistance.
To pinpoint the prime cause of a ground fault, do the following:
- Remove the negative and positive leads from the inverter to confirm its separation from the solar panel array
- In order to apply a live voltage on the wires, secure the DC disconnection
- Evaluate the array’s open-circuit voltage by measuring the voltage between the negative and positive terminals
- Determine both positive and negative to the ground at this point
In the absence of any ground fault, either conductor should have zero volts to the ground. Examine each connection juncture for the entire length leading to the array for existing voltage to ground from both conductors. Once the problem has been identified, change the damaged wires and maintain records of all testing and upgrades.
Excessive current to faulty threads, including reverse current via nearby strings, may overburden conductors and connections, causing excessive heat and the danger of fire. Faulted threads can also have an adverse effect on maximum power point tracking, lowering the PV grid’s efficiency and power production. Look for a service provider who provides a wide range of solutions as well as technical competence to defend against ground-fault occurrences in solar PV panels.