As a kind of connection equipment, the photovoltaic junction box is mainly used between solar charging control equipment and solar cell array (composed of solar photovoltaic modules). This comprehensive product is cross-industry, integrating material science, mechanical and electrical design.
Among the constituent elements of solar photovoltaic modules, the function of the junction box is prominent. Photovoltaic module protection, connection and current transmission are its basic functions. The junction box can adhere to the backplate of the solar panel with silica gel.
The internal line in the junction box is connected with the outgoing line in the solar panel, and the external cable is connected with the internal line, so as to connect the external cable with the solar panel. If the sunlight is blocked, the diode in the junction box can ensure the smooth operation of the solar panel.
Design classification of the photovoltaic junction box
There are many classification methods for photovoltaic junction boxes, some of which are based on the type applied to solar panels, some are based on whether they can be repaired again, and some are based on the size or carrying current.
These have no strict scientific significance, so we see what most people can accept, that is, according to the application occasion. Generally, it can be divided into four types: crystalline silicon solar panel, thin-film solar panel, BIPV and junction box for the intelligent solar panel.
Composition of the photovoltaic junction box
As a solution to human needs, the function of products has always promoted the improvement of products, and safety, as the most important part of human demand for products, also plays a catalytic role in promoting the continuous development of products.
The design and development of a photovoltaic junction box need to be applied to many disciplines such as mechanical design, electronics, material science and so on, The device can be used for connection between solar photovoltaic and the device for managing charging control.
Generally speaking, the most important part of the solar photovoltaic module is the junction box. Its role can be roughly reflected in two points: one is to connect and transmit current, and the other is to avoid damage to the function of the solar photovoltaic module. The photovoltaic junction box is mainly composed of plastic parts (box cover and box body), diodes, metal current-carrying parts, cables, negative connectors and positive connectors.
Functions and properties of the photovoltaic junction box
The photovoltaic junction box can function only when it is placed outdoors to manage the charging process, so it will be affected by various outdoor weather conditions. In addition, because its own electronic components will emit heat, there is a great difference in the internal and external pressure difference.
The influence of weather will aggravate the change of internal and external pressure differences. Therefore, it is necessary to connect with the atmosphere to balance the internal and external differences of the equipment, so as to prevent abnormalities in the use of the equipment.
In addition, it should also pay attention to blocking pollutants generated from the outside during its work. The role of solar cell modules can be summarized into two points: one is connection and transmission, but to protect solar panels from damage.
The new generation of the photovoltaic junction boxes has added remote communication, power monitoring, fault diagnosis, anti-theft protection, fire cut-off, power optimization and improvement, and even module inverter.
Main technical parameters
① The rated working voltage range is below 1500V;
② At present, the rated working current is not greater than 16A;
③ The service temperature range is – 40 ~ 90 ℃;
④ The maximum working humidity is 5% ~ 95% (no condensation);
⑤ The waterproof grade is IP65 ~ IP68.
The technical principle of the photovoltaic junction box
The traditional photovoltaic junction box is mainly composed of a waterproof and dustproof box body, metal current-carrying parts, diodes, cables and connectors. Generally, the junction box will configure the number of diodes according to the number of solar panel strings.
The conduction direction of these diodes in the solar panel is opposite to the output characteristics of the solar panel, that is, for a solar panel that works normally, the diode does not work. When a string of solar panels or a solar panel fails due to shielding, the original “power characteristic” of the solar panel immediately changes to “resistance characteristic”.
At this moment, the bypass diode can be started quickly to flow the current on the string of solar panels from the diode bypass circuit, In this way, the shielded solar cell is protected from damage due to heating. This is the important working principle of the photovoltaic junction box.
