Recently, according to media reports, the solar power box of Haoyao Livestock Farm in Xikou Township, Chiayi County suddenly exploded due to unknown reasons, causing more than 600 deaths and injuries to 2,000 pigs on the farm. Among them, 250 pregnant sows were electrocuted or paralyzed. ,lost heavily. Talking about the cause of the explosion, the relevant personnel said that a bird corpse was found at the power switch after the incident. The preliminary analysis was that the bird accidentally touched the switch, which caused the solar photovoltaic to be unable to be sent back to the Taipower grid, further causing leakage.
It is reported that the livestock farm is to install a photovoltaic system on the roof, that is, a distributed photovoltaic system. In recent years, distributed photovoltaics have been widely used by the public due to their advantages such as flexible application scenarios and on-site consumption. However, in traditional distributed photovoltaics, there are many hidden dangers in the DC high voltage in the system, which will not only cause leakage problems similar to the livestock farm, but also cause arc sparks and other accidents such as fires. In densely populated areas, once a problem occurs, it will bring immeasurable loss of life and property.
It is not difficult to find that with the rapid growth of distributed photovoltaic installed capacity, safety is a key issue that needs urgent attention.
In November 2021, in order to regulate the safety of distributed photovoltaic power generation, the National Energy Administration issued an announcement on public solicitation of opinions on the “Notice on Strengthening the Safety of Distributed Photovoltaic Power Generation (Draft for Comment)”. The announcement puts forward guiding measures to solve the problems such as “DC high voltage” in distributed photovoltaic power plants, and its core demands are mainly two points – safe low voltage and safe shutdown.
Now, let’s discuss the specific solutions of “safety low voltage” and “safety shutdown”.
Safe Low Voltage – Micro Inverter
For DC high voltage, the most thorough solution is the micro-inverter. The micro-inverter is “inherently safe”, and its parallel connection to the photovoltaic system makes the DC side of the system stable at a low voltage of about 40V, which fundamentally eliminates the risk of fire and electric shock.
On the other hand, the quality of micro-inverters is also an important factor affecting the safety of photovoltaic power plants. Hemai strictly controls the micro-inverse production process and device quality. It adopts mature topology solutions in the power supply industry, with reliable structure, sufficient design margin, and a warranty of up to 25 years; and uses aluminum casings to fill the inside of the machine. Glue to enhance the thermal conductivity of the power device to the casing and reduce the internal thermal stress.
At the same time, the micro-inverter is extremely intelligent, with its own component-level monitoring, which can monitor component-level voltage, current, power and other information. No matter where in the world there is a problem with any component, connecting line or connecting terminal, we can easily locate the fault point and fault type through the monitoring platform.
Safe Shutdown – Fast Shutdown
After a fire occurs in the photovoltaic system, a high voltage of hundreds or even thousands of volts will still be generated. If firefighters rush to rescue, it will threaten the lives of firefighters. In this context, MOREDAY released the latest module-level rapid shutdown solution for rooftop string photovoltaic systems.
When an emergency occurs in the photovoltaic system, the connection between each component can be quickly disconnected within 30 seconds, the high voltage on the DC side can be cut off, and the voltage can be reduced to 80v within 30 cm of the system and 30v outside 30 cm to ensure operation and maintenance. Personal safety of personnel and firefighters, and timely maintenance of photovoltaic power plants to minimize property losses.
In addition, fast shutdown has the following advantages
1. Endless compatibility
Breaking through the limitations of the adaptability of various photovoltaic modules, MOREDAY has a multi-series product line, which realizes powerful compatibility functions, and can match photovoltaic modules of different brands, series, power, etc., providing new options for the adaptation of many modules.
2. Easy to install
MOREDAY conducted a lot of research and testing on the installation process of quick shutdown, and finally realized “click and easy installation”, saving time and labor costs, so that novice Xiaobai can quickly get started.
3. Low noise and stability
Typically, a DC arc detection device within a photovoltaic system will identify the signature signal of an arc fault and disconnect the power circuit before the arc fault develops into a fire or a short circuit occurs. However, the working noise of some of the switch-off devices will be misjudged as “dangerous noise” by the device, which will “emergency brake”, stop the system operation, and cause system loss. The working noise of the quick shutdown is far lower than the “warning line”, which avoids the misjudgment of the system and ensures the power generation income of the photovoltaic power station.
For a long time, MOREDAY has been committed to the research and development of safe and efficient distributed products. Its rapid shutdown technology can effectively solve the safety problems caused by the DC high voltage in the traditional photovoltaic system, and the strength guarantees the “safety low voltage” and “safety shutdown” of the photovoltaic system.
Post time: Jul-11-2022