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Rooftop distributed photovoltaics have been widely used in Europe, the United States, Australia, China and Japan. As the application of photovoltaic power plants in the area closest to human activities, more and more emergency personnel and firefighters are aware of the potential safety hazards of photovoltaic systems. How to ensure personal safety, how to prevent the fire risk of photovoltaic facilities, and how to ensure that non-professionals identify and cut off risks at the first time have become issues of common concern in various countries.

Potential safety hazards of photovoltaic systems

In fact, photovoltaic systems are not as safe as we think.

We all know that the DC isolation switch is integrated in the photovoltaic inverter, but even if the DC isolation switch is turned off, there is still a voltage as high as 600~1500Vdc between the inverter and the photovoltaic panel. As long as there is radiation on the solar panel, the DC side will generate a voltage of 600~1500Vdc. In the event of a fire in an installation without quick shutdown, high voltage DC currents inside the panel array or between the panel array and the inverter will threaten the safety of firefighters. On the other hand, the circuits of most photovoltaic power plants use 600~1000V (some even as high as 1500V) DC circuits. In actual power stations, DC arcs may be caused by faults such as poor connections, poor contact quality, insulation aging, and insulation moisture. When a DC fault occurs, the PV modules continue to generate electricity. The DC current does not cross zero, so the fault current at the trigger location will continue for a long time and further start a fire with a very serious potential hazard for firefighters. According to market demand, MOREDAY has successively launched string-level and component-level fast shutdown.

MOREDAY rapid shutdown ensures the safety of PV system

MOREDAY RP series rapid shutdown is suitable for residential photovoltaic systems or industrial and commercial photovoltaic systems, and its maximum loop voltage can reach 1500V, which meets the requirements of high-power photovoltaic panels.

l Gain valuable time for firefighting

The RP series quick shut-offs comply with international standards for firefighters’ work procedures. When a fire occurs in the photovoltaic system, the AC terminal current will be disconnected first. At the same time, MOREDAY Quick Shutdown will collect the power failure signal. If the power failure time exceeds 5 seconds, it will automatically disconnect the isolation switch and then disconnect the DC side, creating a safe environment for firefighters. On the other hand, with the advanced temperature sensor monitoring the temperature inside the case in real time, MOREDAY’s fast shutdown can automatically open the switch when the internal temperature exceeds 70℃.

l Completely isolated solar panels

The RP series uses MDIS DC isolating switches, which can be directly used in photovoltaic panels. In the event of a fire, Quick Shutdown quickly shuts down the PV array without any risk of high DC voltages. If the customer wishes to achieve a lower DC voltage across the roof (for example, below 80V~120V), multiple safety switches (one for every 2-3 panels) can be applied to ensure maximum safety.

l Automatic reset

MOREDAY’s RP series fast shutdown auto reset. When AC power is turned off (such as during a power outage) and then power is restored, the RP series will reset and automatically connect the circuit quickly. The client does not need to reset it manually every time.

l No need for additional network, with more stable switching capability

Compared with the common fast isolation devices on the market using remote communication technology, the PEFS series fast shutdown is directly controlled by the AC circuit without additional networking. It only uses the existing AC power system. In addition, MOREDAY does not perform the on-off function through electronic components, but performs the on-off function through the isolation switch with arc extinguishing function, which directly disconnects the DC circuit with higher stability.

l Extend the service life of PV inverter

When MOREDAY’s RP products are installed in the system, the DC circuit will automatically shut down if the AC circuit is not energized, such as during a power outage, power line maintenance or grid failure. This will greatly extend the life of the PV inverter and make it safer to repair or replace the PV inverter.

l Use the most popular DC switches

MOREDAY’s RP series is equipped with MD DC disconnect switch, which is the most popular DC disconnect switch for photovoltaic applications in the world. The MOREDAY spring structure bounces with a response time of just 5 milliseconds, which quickly extinguishes the arc. Combined with self-cleaning contacts, the switch offers increased durability and safety. Therefore, many PV inverter manufacturers choose MD as the first choice for DC disconnector.

l Professional DC isolating switch manufacturer

MOREDAY has extensive experience in developing DC disconnect switches with customers all over the world. MOREDAY has become the first company in China to develop a DC arc extinguishing capability without using remote communication technology, effectively ensuring the safety of high-voltage DC roofs.

l 25-year long-life design of photovoltaic system

MOREDAY’s RP series products use industrial grade capacitors and motors, and strictly control key internal components. It can work normally in harsh environments ranging from -20°C to 70°C. Equipped with waterproof breathable valve to effectively avoid cavity condensation. The design life can meet the operating requirements of the photovoltaic system for 25 years.

With excellent performance and a professional after-sales team that quickly responds to customer needs, this product is popular in the European market and continues to be well received by customers.