Electric boxes are usually used in photovoltaic power generation systems, which are divided into DC combiner boxes and AC distribution boxes. In the photovoltaic power generation system, the electric box is a wiring device that ensures the orderly connection and confluence function of photovoltaic modules. The combiner box can combine the electric energy after the photovoltaic series, and use it together with the controller, photovoltaic inverter, and AC power distribution cabinet to form a complete photovoltaic power generation system and realize grid connection with the mains.

Photovoltaic box function introduction

Photovoltaic boxes are divided into two categories: DC boxes and AC boxes. The DC power box is equipped with PV-specific DC lightning protection modules, DC fuses and DC isolation switches, which are convenient for users to grasp the working conditions of PV cells in a timely and accurate manner and ensure that the solar PV power generation system exerts the maximum effect. The DC box is mainly used as the disconnection point between the photovoltaic module and the inverter to provide protection for the maintenance personnel of the inverter.

The AC box is installed between the AC output side of the inverter and the grid-connected point/load. It is mainly composed of a circuit breaker CB, a surge protector SPD, a leakage protector RCCB, and a smart meter can also be used to detect the system voltage, current, power, and electrical energy. and other parameters. The AC box can be used as an inverter output disconnect point to provide system security, protect the safety of installation and maintenance personnel, and can also be used as a bus for multiple inverters.

Electric box technical parameters

The main technical parameters of the electric box are determined according to the system, taking the DC electric box as an example:

1, to determine the DC system voltage;

2. To determine the rated peak current of the photovoltaic string, the usual current is divided into two gears lower than 15A and lower than 20A;

3. Determine the number of input loops, usually the number of strings;

4. Determine the number of output loops, this parameter is mainly determined by the system power and the inverter used;

The model and quantity of the required electrical box components can be determined through the above parameters. The above are the parameters required by the conventional electric box. If there are other requirements, special components can be added to the electric box, such as DC meters, monitoring systems, etc.

The design of the AC box is mainly determined according to the way of connecting to the grid or the load situation. For household photovoltaic AC boxes, a single-phase layout is generally adopted, and the indoor loads are jointly protected by the AC micro-break MCB, the leakage protector CCB and the AC surge protector. In some cases, components such as smart meters will be added.

in conclusion

The photovoltaic box is an important part of the photovoltaic system. This article introduces the DC box and the AC box from various aspects. When choosing equipment, you need to choose from materials, design, technology, testing, certification and other aspects, so as to reduce equipment failure, reduce the cost of operation and maintenance, and increase the safety of the photovoltaic system.