Part 1: Equipment-level inspection and operation and maintenance SOP for PV side components and array systems of photovoltaic power stations (corresponding to topology module 1)
This article corresponds to the panoramic topology diagram of the photovoltaic power station [Module 1: Photovoltaic modules and square array system], covering photovoltaic module glass/backplate appearance inspection, infrared hot spot scanning, junction box bypass diode test, portable EL crack detection, PID effect (potential induced attenuation) nighttime pressure repair and photovoltaic module standard cleaning operations.
1. Photovoltaic module physical appearance and structural maintenance SOP
(1) Tempered glass and backplane packaging maintenance
Inspection of tempered glass and anti-reflective coating: Check that there are no spider web-like bursts and cracks on the surface of the glass; check that the anti-reflective (ARC) coating has no peeling, scratches or peeling; check that the silicone sealing edge at the junction of the glass and the aluminum alloy frame has no degumming or cracking.
Backsheet and double-glass module packaging inspection:
Single-glass module backplane: Check that the backplane has no yellowing, no scratches, no exposed copper, no bubbles, bulges, and no delamination. When the backplane is deeply scratched and has a fluorine coating, moisture can easily invade and cause the insulation to drop to 0 MΩ.
Double-glass components: Check that the POE/EVA film on the front and rear double-layer glass edges has no aging bubbles, no water vapor snail trails, and black tracks.
(2) Aluminum alloy frame, pressure block bolts and ground jumper
Tightening torque of frame and pressure block: Use a torque wrench to randomly test the middle pressure block and side pressure block bolts of the assembly. The tightening torque of M8 stainless steel bolts must be maintained at 16.0 ~ 20.0 N·m, and the locking washers must be well locked. The pressing block must not compress the effective light-emitting area of the battery piece.
Module ground jumper resistance test: Use a microohmmeter to test the jumper resistance of the module's aluminum alloy frame to the photovoltaic bracket's ground terminal. The on-resistance must be ≤ 0.1 Ω. If the grounding bolt is found to be corroded, sand it with sandpaper and retighten it, and apply anti-rust conductive paste.
(3) MC4 DC plug polarity, temperature rise and junction box
MC4 quick plug arc prevention maintenance:
Polarity check: When reconnecting after disassembly and maintenance, you must use a multimeter to measure the positive and negative polarities. Reverse polarity is strictly prohibited.
Buckle and seal: Check whether the waterproof rubber sealing rings of the positive and negative MC4 plugs have aged and fallen off; the plug handle is locked firmly and there is no looseness due to tripping.
Infrared Thermometry: Use an infrared camera to scan a running MC4 plug. The operating temperature rise of the plug must be < 15.0 ℃, and the operating temperature must be < 60.0 ℃. If the plug is found to be discolored and black or the temperature rise exceeds the standard, it means that the contact resistance is too large. The circuit must be cut off and re-crimped to replace the new MC4 terminal.
Appearance and sealing of the junction box: Check that the junction box shell is not cracked or deformed, and that the box cover is fastened; the outlet anti-pulling nut (Cable Gland) is tightened and not loose.
2. Component hot spot effect (Hotspots) and junction box bypass diode maintenance SOP
(1) Infrared thermal imaging (FLIR) hot spot scanning SOP
Test meteorological conditions: Scanning operations must be carried out when there is sufficient sunshine, solar irradiance must be ≥ 700 W/m², wind speed < 4.0 m/s, and the entire station's photovoltaic array must be operating at full power.
Hot spot classification and treatment standards:
General hot spots (10.0 ℃ ≤ ΔT < 20.0 ℃): Single point slight heating, partially blocked by dust or bird droppings -> Record the number and include it in the cleaning and maintenance plan; retest after washing.
Severe hot spots (ΔT ≥ 20.0 ℃ or T ≥ 80.0 ℃): severe heat generation, EVA film turns yellow, and back panel is burnt -> Isolate the component and replace it within 48 hours to prevent fire.
Bypass breakdown: The entire string/half string of cells generates heat and temperature rise -> The bypass diode in the junction box breaks down and is short-circuited -> During a power outage, disassemble the junction box, measure and replace the bypass diode.
(2) Junction box bypass diode (Bypass Diode) detection SOP
When the bypass diode is short-circuited by reverse high voltage, the entire string or half of the string of cells will be bypassed normally, resulting in a loss of 1/3 or 1/2 of the module power.
Step 1: Open the DC input breaker/unplug the MC4 plug for the string to bring the assembly offline.
Step 2: Open the junction box cover and set the multimeter to the "diode measurement position".
Step 3: Connect the red test lead to the positive electrode of the diode, and the black test lead to the negative electrode, measure the forward voltage drop (the forward voltage drop of the Schottky diode must be between 0.30 ~ 0.70 V).
Step 4: Change the test leads to measure the reverse resistance. The impedance must be close to infinity (> 1.0 MΩ). If the reverse resistance impedance is close to 0 Ω, it is determined that the diode is broken down and short-circuited, and a soldering iron must be used to replace the diode of the same specification (such as 20A / 45V).
3. Portable EL Crack Test and PID Effect (Potential Induced Decay) Prevention SOP
(1) Portable EL (electroluminescence) crack detection SOP
Cell micro-cracks are internal physical fractures that are invisible to the naked eye and will seriously affect component life.
Step 1: The test must be conducted at night or in a special blackout environment.
Step 2: Connect the DC power output of the portable EL tester to the positive and negative MC4 plugs of the PV module.
Step 3: Apply a forward current that matches the open circuit voltage (usually 8.0 ~ 10.0 A) to the component, so that the cell sheet is excited to emit near-infrared light (800 ~ 1100 nm).
Step 4: Capture EL images using a highly sensitive infrared camera.
Judgment criteria: The dark and dark areas in the image are dead chips or cracks. When the cracked area of a single cell exceeds 10% of the total area of the cell, or there are cross fractures (Black Hearts), it is judged to be unqualified and the component must be replaced.
(2) PID effect (potential induced decay) diagnosis and Anti-PID nighttime reverse pressure repair SOP
The PID effect is that under the action of high-voltage DC (1000V/1500V), a high-voltage electric field is formed between the module frame and the cell sheet, causing sodium ions (Na+) in the glass to migrate to the surface of the cell sheet, causing a severe attenuation of 10% to 50% in power within 1-2 years.
PID diagnosis: In the SCADA system, it was found that the open-circuit voltage Voc of a certain string was normal, but the full-load operating current and power dropped significantly; the EL test showed a large number of black blocks on the edges of the battery cells.
Anti-PID nightly reverse pressure repair process:
Step 1: Install an intelligent PID repair generator (Anti-PID Box) on the AC side of the string inverter or the DC side of the combiner box.
Step 2: Set the PID generator control logic: When the weather station detects irradiance < 10 W/m² and the inverter stops working for 30 minutes, the PID generator starts automatically.
Step 3: The PID generator applies 500V ~ 1000V DC high voltage (current limited to < 5 mA) to the DC negative electrode of the photovoltaic array to the ground, and pressurizes continuously for 6 ~ 8 hours.
Step 4: 30 minutes before sunrise, the PID generator automatically cuts off the high voltage and returns to ground, and the inverter starts normally. After 3 to 7 consecutive nights of repair, the component power can be restored to more than 90%.
4. Photovoltaic module standard cleaning SOP (standardized operating procedure)
Cleaning period control (mandatory anti-explosion standard):
It is strictly prohibited to clean components during high-irradiation periods at noon! When exposed to direct sunlight, the surface temperature of the module glass can reach 50 ~ 60 ℃. At this time, rinse with cold water. The severe thermal expansion and contraction stress will instantly cause the entire tempered glass to burst.
Best cleaning time: 1 hour before sunrise to 2 hours after sunrise, or in the evening after sunset.
Water quality and water pressure standards:
Water quality requirements: The pH value of the flushing water must be between 6.0 and 8.0 (neutral); the water hardness must be < 100 mg/L (hard water flushing will leave white calcium and magnesium scale on the glass surface, which is difficult to remove).
Water pressure control: The pressure of the high-pressure water gun nozzle must be < 0.40 MPa. It is strictly prohibited to use high-pressure columnar water flow to directly spray the back panel, junction box and MC4 interface of the component.
杂草与树木遮挡刈割：
Weeds in the front rows and between the rows of the square array should be mowing and cleared every quarter, and the height of the weeds should be controlled below the height of the lower edge of the module (usually < 30 cm) to prevent hot spots caused by grass shadows.
Photovoltaic power station PV side components and array system equipment level inspection and operation and maintenance sign-in form
Power station name: _______________________________ Inspection date: ____ month ____ day, 2026
Inspection area: Photovoltaic module array area Inspection person in charge: ____________________
1. On-site equipment inspection and test data recording:
2. Inspection defect registration and defect elimination dispatch
3. Inspection sign-in and review signature
Inspection Engineer (Signature): _______________ Supervision Engineer (Signature): _______________
Review (signature) of the shift leader: _______________ Sign-in and filing time: ____ hour on ____ month ____ day 2026