Analysis of the causes of fire accidents on the DC side of photovoltaic power generation systems

Photovoltaic power generation systems are getting closer and closer to our lives. The attached picture shows some accident cases of photovoltaic power generation systems, which should attract the great attention of photovoltaic practitioners.

In order to facilitate your reading, I have listed some of the causes of photovoltaic DC side fire accidents for your reference. Please correct any shortcomings.

1. The pin crimping between the photovoltaic cable and the connector is unqualified;

2. Photovoltaic connectors of different brands can be plugged into each other;

3. The positive and negative poles of one or more photovoltaic strings are reversely connected;

4. The waterproof performance of the positive O-ring and the tail T-ring of the connector is not up to standard;

5. Photovoltaic connectors or photovoltaic cables have been in a humid environment for a long time;

6. The cable skin was cut or excessively bent during the laying process;

7. In the grid-connected state, plug and unplug the connector;

8. Any point in the photovoltaic string circuit should be grounded or form a path with the bridge.

Below I give the following explanations for each of the above reasons, please refer to them.

    1. The pin crimping of photovoltaic cable and connector is not qualified.

Due to the uneven quality of construction workers, or the construction party not providing professional training to the workers, unqualified photovoltaic connector pin crimping is the main reason for poor contact between photovoltaic cables and connectors, and is also one of the main reasons for photovoltaic power generation system accidents. one. The picture below is a sample obtained by the author from a photovoltaic power station that is not connected to the grid. Just pull the cables on the inverter side gently and almost all the cables will come out in one pull. It can be seen that the cable and the connector are only briefly connected. The exposed cable with a voltage of nearly 1000V may break away from the connector at any time and fall on the color steel tile or cement roof, ignite, and cause a fire accident.

The correct installation sequence is shown below. Please be sure to install the connectors at both ends of the photovoltaic cable before connecting the module side and the inverter side.

This 4-step method is designed to accommodate single-person operation.

Please see the next chapter for explanations of the remaining seven reasons.