How to check the solar system? What are the main subjects of the physical examination?
PV module physical examination
The energy of the photovoltaic system comes from the photovoltaic modules. The occurrence of cracks, hot spots, dust accumulation, and poor wiring in the photovoltaic modules will directly affect the power generation capacity of the power station. Therefore, the physical examination of the modules is very necessary. The physical examination steps are as follows:
01
Component Dust Check
Component dust accumulation is the most common problem in operation. If you want the power station to generate high power, it is necessary to keep the lighting surface of the components clean. If there is dust, it can be washed with a soft brush and clean water. The force of use should be small. It is forbidden to wipe the photovoltaic modules with hard objects, and do not clean with corrosive solvents. If there is snow, it should be cleaned in time; Do it in the morning or evening when the light is low.
02
PV module integrity check
Photovoltaic modules should be inspected regularly, such as quarterly or yearly. If glass is broken, backplane is burnt, battery is discolored, junction box is not tightly sealed, deformed and twisted, cracked or burned, plugs are loose, fall off, and corrode, etc. Repair or replace in time.
03
Photovoltaic module shading inspection
The power station runs outdoors for a long time and is often left unattended. It is necessary to check whether there are new growth plants or other objects that block the components. If there are shadows, they need to be dealt with in time to avoid affecting the components and power generation.
04
Component Wiring Check
For photovoltaic modules with metal frames, the frame and the bracket should be in good contact, make sure that the mounting bolts have been firmly connected to the oxide film of the aluminum frame, the frame must be firmly grounded, and the grounding resistance should not be greater than 4Ω.
05
String current check
Use a DC clamp-type ammeter to measure the input current of each PV module string connected to the same inverter under the condition that the solar radiation intensity is basically the same. The current deviation of the same model and the same group of modules is generally not more than 5%. , need to be checked in time.
06
Thermal imaging inspection of components
If conditions permit, an infrared thermal imager can be equipped to regularly detect the temperature difference on the outer surface of the photovoltaic module; it can timely find out the health status of the electrical equipment in the system, and prevent potential power loss and safety hazards in time.
Inverter physical examination
The inverter is the brain of the photovoltaic power station. The external operating status information of the photovoltaic power station is basically sent by the inverter. The operating status of the inverter is also an important step in the physical examination. The inspection items are as follows:
01
Inverter appearance inspection
The inverter structure and electrical connections should be kept intact, and there should be no rust, dust accumulation, etc.; there should be no large vibration and abnormal noise when the cooling fan is running. , maintain good cooling and ventilation.
02
Inverter Wiring Check
Strictly and regularly check whether the wiring of each part is loose (such as fuses, fans, input and output terminals, and grounding, etc.), and repair the loose wiring immediately.
03
Inverter monitoring data check
The current inverters all have the function of intelligent communication monitoring. During the physical examination, it is necessary to check whether the communication data of the inverter is normal, whether the inverters of the same capacity at the same time period, and whether the generated power is close. If it is found that an inverter shows a large power deviation , to check the cause in time; at the same time, you can view the operation data and fault code of the power station through the Growatt monitoring APP or web page, which is convenient to find the cause of the fault.
04
Protection function check
If the circuit breaker on the AC output side (grid-connected side) is disconnected once regularly, the inverter should immediately perform anti-islanding protection action and stop feeding power to the grid. This function can ensure the safety of operation and maintenance personnel.
Physical examination of distribution box
There are many switches, lightning protection and other electrical equipment in the photovoltaic power distribution box, and it is also a place where faults occur frequently.
01
Checking the voltage switch
The general photovoltaic power distribution box mainly includes electrical switches such as AC circuit breakers, lightning protection switches and knife switches. During the physical examination, the quality of the switches is mainly checked. Whether there is no action or damage, especially the installed outdoor power distribution box, which is prone to inductive lightning strikes, it is necessary to regularly check whether the lightning protection switch is in good condition.
02
Wiring Check
The power distribution box has to pass through the large current on the AC side of the inverter, which is prone to generate heat fault points. During the physical examination, it is necessary to check whether the terminals have serious heating, blackening, burning and other abnormal conditions. If found, they need to be replaced in time. At the same time, the inlet and outlet sides of the distribution box need to be sealed with fireproof mud to prevent animals such as reptiles or mice from entering the distribution box outdoors and cause short-circuit faults.
Physical examination of photovoltaic support
The role of photovoltaic brackets in photovoltaic systems is to protect photovoltaic modules that can withstand the gravity of photovoltaic modules for 25 years and not be damaged by natural conditions such as strong winds and heavy snow. The materials of the brackets are mainly stainless steel and galvanized steel, etc. Generally, the compression resistance, strong wind resistance and corrosion resistance are very good.
01
Stability Check
Photovoltaic brackets have been exposed to wind and rain for a long time outdoors, and the connectors are easily loosened due to various tensions. During the physical examination, it is necessary to check that all bolts, welds and bracket connections should be firm and reliable, and the stability of the component bracket should be checked. If the bracket bolts and nuts are loose, they should be stabilized in time.
02
Corrosion resistance inspection
According to the actual situation of the installation site, such as in a high temperature and humid operating environment, it is necessary to regularly check whether the metal bracket is rusted.
03
tracking bracket
For solar cell array supports with polar axis automatic tracking system, it is necessary to regularly check whether the mechanical and electrical performance of the tracking system is normal.
Physical examination of cables
AC and DC cables are generally hidden works in photovoltaic systems. The cables will be laid through pipes or through bridges. The inspection is slightly more difficult, but it cannot be ignored.
01
Visual inspection
The photovoltaic cables connected between the modules should be tied reliably, without looseness or damage; the cable identification plate should not be missing or damaged, and the identification and writing of each string should be clear and easy to identify. If there is damage, it should be replaced in time. For cables and terminals connected to outdoor and overhead lines, check whether the terminals are complete, and whether the contacts of the lead wires are hot or black.
02
Seal check
The parts at the inlet and outlet of equipment such as combiner boxes and bridges should be well sealed, and there should be no holes larger than 10mm in diameter, which should be blocked with fireproof mud.
03
Cable Integrity Check
Make sure that the cable terminals are well grounded, the insulating sleeves are intact, clean, and have no traces of flashover discharge; make sure that the cables have obvious phase colors; for multiple cables laid in parallel, check the current distribution and the temperature of the cable sheath to prevent damage caused by poor contact The connection point of the cable is burned out; the cable should not run under overload, and the lead package of the cable should not be expanded or cracked; where the cable has too much pressure and tension on the equipment shell, the support point of the cable should be intact; check When the indoor cable is open in the trench, it is necessary to prevent damage to the cable; ensure that the bracket is grounded and the heat dissipation in the trench is good.
04
ground check
The metal cable tray and its support and the incoming or outgoing metal cable conduit must be grounded (PE) or zero-connected (PEN) reliably; the tray and the tray should be connected with a ground wire reliably.
In winter, the power generation of photovoltaic power plants decreases, so there is no need to be nervous. This is a normal phenomenon, because the duration of sunshine in most areas becomes shorter in winter. At this time, it is very necessary to carry out a comprehensive year-end physical examination for the power station, so as not to delay the power generation, but also to escort the continued safe and efficient power generation in the coming year.