For solar power systems of daily life and industrial, to improve stability and system maintenance, it’s generally necessary to add a PV combiner box between solar panels and inverters, connect solar panels in series to the PV combiner box for convergence, and then connect to the inverter. In order to help people understand how the combiner box work, that’s what we want to talk about today.
What is PV Combiner Box?
In the solar power generation system, the PV combiner box is an important wiring equipment that ensures the orderly connection of solar panels and the confluence function. It means that the user can connect a certain number of solar panels with the same specifications in series to form a PV series, and then connect several Solar panels in series. The panel strings is connected to the PV combiner box in parallel, and after the combiner box is combined, it is connected to the solar inverter for power supply.
The Function of PV Combiner Box
The combiner box is a product special to collect current. It’s mainly used in medium-sized and large solar power systems. The quantity of strings in the PV array is large also the output is large. So we will need a device to collect these outputs so that they can be directly connected to the inverter. In a solar power system, the combiner box is a wiring equipment that ensures the orderly connection of solar panels and combination. The equipment can ensure that the solar power system easy to cut off the circuit during maintenance and inspection, and reduce the scope of power outage when the system fails.
Lightening Protection Design of Combiner Box
Since the solar power system is installed in an outdoor environment, lightning strike protection must be considered. To this end, the DC output components of the combiner box can be equipped with DC MCB, DC SPD and DC Fuse, and set up working status indicators, lightning counters, etc. Once a lightning strike occurs, the lightning protection part will quickly discharge the excessive electrical energy to ensure stable output of electrical energy and protect the combiner box from lightning. The lightning protection components installed in the combiner box are called PV lightning protection combiner boxes, which ensure the maximum effect of the solar power system.
The Inner Accessories of Combiner Box
1. Shell
The PV combiner box shell is generally made of steel plate sprayed with protective layer, stainless steel or engineering plastics. It is beautiful in appearance, strong and durable, simple and convenient to install. The protection level can reache IP54 or IP65, and meets the requirements of long time use.
2. DC MCB/DC MCCB
DC MCB/MCCB is the output control device of the whole combiner box, which is mainly used for opening/closing of the line. Its operating voltage is up to DC1000V, and can be customized to 1500V. Since the solar module can generate direct current, it’s easy to produce arc when the circuit is off. Therefore, the DC breaker must be selected.
3. DC Fuse
When the backflow current occurs in the module, DC fuse can cut off the fault string in time, the rated working voltage is up to DC1000V, while 1500V DC fuse is available in 1500V PV combiner box; and the rated current of dc fuse is generally selected as 15A, 20A will be selected in some projects. The DC fuse is a special designed for solar power system. It’s installed with a special closed base to avoid the burning of modules due to the backflow of current between groups. When the current backflow occurs, it will quickly exit the faulty string from the system operation, while not affecting other normal working strings, which can safely protect the PV string and its conductor from the threat of reverse overload current.
4. Anti Reverse Diode
The function of the diode in the combiner box is different from that of the component junction box. The diodes in the junction box of the components are mainly used to provide a continuous flow channel when the battery is blocked, while the diodes in the combiner box are mainly used to prevent the circulation between the strings.
5. DC SPD
DC surge protective device is a special lightning protection product for solar power system, with double self-protection function of overheating and overcurrent; Adopt modular design, can be replaced with electricity, and have deteriorated display window.
Features of PV combiner box
I. It can connect multiple PV arrays at the same time, meet the needs of different user;
II. Each input is independently equipped with DC high-voltage lightning protection circuit, which can ensure that lightning strikes do not affect the normal output of the PV arrays;
III. The output end is connected with a DC high-voltage lightning protection module, which can suffer a maximum lightning current of 40kA;
IV. Use high-voltage circuit breakers, and the DC withstand voltage value is not less than DC1000V/1500V, which is safe and reliable;
V. With the lightning recording function, it’s convenient to understand the intrusion of lightning disasters;
VI. The protection level reaches IP54/IP65, outdoor installation will be no problem.
Through the above sharing, wish everyone has a clear understanding of the PV combiner box. In general, a large solar power generation system requires a lot of solar panel arrays. In order to reduce the connection lines between the solar panel array and the inverter and simplify the system structure, it is necessary for the PV combiner box to connect these lines in parallel.
