Crucial Measures for Photovoltaic System Reliability: Overload and Short-Circuit Protection

Photovoltaic power systems have become a critical component of the renewable energy sector. However, like any other electrical system, photovoltaic systems also require effective protective devices to ensure their proper operation and prevent potential hazards. In this article, let’s discuss overload and short-circuit protection in photovoltaic systems and the importance of protective devices in maintaining system safety and reliability.

Overload Protection

Overload refers to a situation in which the electrical energy generated by a photovoltaic power system exceeds its design and rated capacity. This situation often leads to a decrease in the system’s operational performance and can potentially affect its reliability and safety.

Factors that Lead to Overload

1. Incorrect System Design: Improper product selection can lead to overloads. The products used should have a current rating 1.3In times greater than the system’s current. For example, if the system current is 13A, the selected product should have a rating of 20A to prevent overheating and overload trips. Incorrect sizing of system conductors can also cause overload.

2. Environmental Factors: External environmental factors like extreme weather conditions can  lead to physical damage to solar panels and connections, thus resulting in overloads. An non-compliant increase in wiring and solar panels can also cause overloads.

Short-Circuit Protection

A short circuit refers to direct contact between two adjacent conductors in an electrical circuit, leading to a rapid increase in current. This often results in electrical arcing and a significant current flow through the equipment, potentially causing severe safety incidents.

Factors that Lead to Overload

In photovoltaic systems, short circuits can occur due to various reasons:

1. Damaged Wires or Connections: Damaged, broken, or short-circuited wires can lead to abnormal current paths. This typically occurs when the external insulation of wires is compromised, for instance, due to crushing, abrasion, or moisture ingress. When wires are damaged, the current may bypass the normal path, leading to a short circuit.

2. Wear and Tear of Solar Panels: Damaged connections or components within solar panels can result in short circuits. Solar arrays are often constructed by connecting multiple solar panels in series or parallel to form a module. If the connections on the solar panels are physically damaged, such as cracked or broken connections, the current may bypass the damaged area, creating a short circuit.

3. External Factors: Various external factors can contribute to short circuits. Rodents or other animals may chew on insulation, compromising the integrity of the wires. Tree branches or other external objects making contact with the solar panels’ wiring or components can also lead to short circuits. Extreme weather conditions, like lightning, hail, or temperature extremes, as well as water ingress, may cause damage to solar system components, leading to short circuits.

Devices for Overload and Short-Circuit Protection

To protect photovoltaic systems from overload and short-circuit hazards, a variety of protective devices are commonly employed, including (but not limited to) the following:

A. Fuse Holders: They are one of the most common overload and short-circuit protection devices. When the current exceeds a safe threshold for a certain period or a short circuit occurs, the fuse melts due to the heat generated within, thereby cutting off the circuit to prevent equipment damage or fire. Once a fuse is tripped, it needs to be replaced to restore the protection function.

B. Circuit Breakers: They serve a function similar to fuse holders. When overload is detected, circuit breakers operate by using an electromagnetic tripping mechanism to open the circuit. Unlike fuse holders, circuit breakers can be reset after tripping, providing a means for quickly restoring power.

C. Other Devices: Supplementary protective devices such as current limiters, voltage and current monitors, and current protectors are used to limit and monitor current and voltage effectively.

*In addition to protective devices, ensuring the proper sizing and design of conductors and components to handle system loads and maintaining correct grounding and insulation measures is essential. Regular inspection and maintenance of photovoltaic systems to identify and replace damaged wiring or components are also crucial in preventing overload and short-circuit situations.

Beny’s Reliable Circuit Breakers and Fuse Holders

Beny offers a range of circuit breakers and fuse holders designed specifically for photovoltaic power systems to meet various user requirements:

BB1-63/BB2-40 DC Miniature Circuit Breakers: Suitable for photovoltaic and energy storage systems, these devices provide overload, short-circuit, and anti-backflow protection while featuring an arc-flash barrier to enhance system safety. BB1-63 is designed for DC 1200V systems with a current rating of up to 63A, while BB2-40 is for DC 1500V systems with a current rating of up to 40A. Both products have obtained certifications such as TUV Rheinland, CE, CB, TUV Australia, and UL (BB1-63 only) to meet market demands.

BD Series DC Molded Case Circuit Breakers: Primarily intended for large solar power systems, including DC combiner boxes, inverters, and DC distribution cabinets. These circuit breakers provide overload and short-circuit protection, with a rated voltage of up to DC 1000V and a current rating range of 63A to 250A. They have been subjected to extreme environmental testing from -40°C to +85°C and hold certifications like CE, CB, and TUV to ensure product reliability.

BDM Series DC Molded Case Circuit Breakers: Designed for commercial solar PV battery storage systems, electric vehicle chargers, and UPS applications. The product complies with IEC standards, featuring a rated operating voltage of DC 500V and a rated current range from 65A to 250A. It offers both overload protection and control for DC circuits. The product has been tested under extreme environmental conditions from -40°C to +85°C and can be equipped with an IP65 UV-resistant lockable enclosure for outdoor installation to meet stringent operational requirements and enhance safety and reliability.

DC Fuse Holders: Specifically designed for residential and commercial photovoltaic systems, providing overload and short-circuit protection. These products conform to IEC standards and are suitable for high-voltage systems with DC 1000V and DC 1500V ratings. They offer current ratings of up to 30A and include LED indicators to display their operational status. Additionally, they have received certifications like CE and RoHS to meet market requirements.

In photovoltaic systems, overload and short-circuit protection are essential to ensure system safety and reliable operation. Understanding the functions and proper use of various protective devices is crucial for reducing system failures, circuit damage, and potential fire hazards. By correctly installing and maintaining these devices, the performance of photovoltaic systems can be preserved, providing a reliable safeguard for the sustainable use of clean energy.