How Can Solar Panel Damage Be Prevented | Weather Protection, Installation Quality Inspection

Selecting anti-wind ≥ 2400Pa, anti-snow ≥ 5400Pa modules and adding installing protective frame; standardizing installation torque error ≤ 5%; every half year inspecting bracket and wiring, can lower failure rate about 20%–30%.

Weather Protection

Resist big wind

When the wind speed reaches 30 meters/second, a piece of area being 2.5 square meters' conventional solar panel will bear about 130 kilograms' upward wind pulling lifting force. If the installation tilt angle is set at 15 degrees to 20 degrees, the panel back face's aerodynamic lift coefficient will be compared to 0 degrees flat paving installation time lower 25%. At roof arranging modules time, edge place must leave out at least 50 centimeters' yielding distance, avoiding roof eaves place magnified 1.5 times' eddy current wind pressure tearing bottom part's fixing fixture.

· Fixing pressing block needs to use anti-pulling strength reaching 800 megapascals' M8 specification 304 stainless steel bolt, construction time using torque wrench putting tightening torque controlled at 18 to 20 newton·meters between.

· Aluminum alloy guide rail's supporting span is strictly limited to 120 centimeters within, in order to guarantee per square meter 1.5 kilonewtons' static load can evenly distribute at 4 pieces of fixing points.

· At wind speeds all year round exceeding 35 meters/second's region, every interval 2 meters spacing needs to add install a root thickness being 4 millimeters' oblique direction aluminum pull rod, putting bracket's physical deformation amplitude limited at 3 millimeters within, preventing hidden crack producing.

Block hail

Diameter 25 millimeters' hail with 23 meters/second's free falling body speed smashing toward panel time, instantly produced's impact kinetic energy is about 1.2 joules. Surface covering 3.2 millimeters thickness AR coating tempered glass's module, is able to bear 50 times the same strength's continuous impact, and glass shattering rate is 0%. Putting bracket's installation tilt angle from 15 degrees lift high to 35 degrees, hail contacting glass surface's incidence angle will happen deflection, vertical direction on's destroying force will follow it attenuate 40%.

· In high-frequency hail-falling regions, at module exact above 15 centimeters, place add install mesh hole diameter being 15 millimeters' stainless steel protective net, material cost per square meter increases about 30 yuan.

· This layer metal net is able to absorb 40 millimeters big hail 85% of its initial kinetic energy, putting single piece 550 watts panel's suffered damage probability from 12% large amplitude press low to 0.2%.

· The frame needs to adopt a thickness of 35 millimeters' anodized aluminum oxide profile, at multiple points impact under, can ensure the whole piece 3.2 millimeters glass's inward concave bending degree not exceeds 5 millimeters.

Temperature control

Solar panel's standard test temperature baseline is 25 degrees Celsius, working temperature every rises 1 degree Celsius, output power then will fixedly drop 0.35%. At an air temperature of 35 degrees Celsius on a summer afternoon, the actual measured temperature of a dark color glass surface will rapidly soar to 65 degrees Celsius, leading to system current peak power generation efficiency permanently flow lose 14%. At the panel bottom part, constructing passive heat dissipation's airflow channel, is an item with an extremely low cost but a return rate reaching 300% physical cooling scheme.

· Solar panel bottom part and roof surface between reserve 15 to 20 centimeters' vertical ventilation gap, allowing environment wind with 1.5 meters/second's flow speed continuously pass through.

· This kind of continuous air convection can put the junction box's working temperature lower by 8 to 12 degrees Celsius, exchange back about 3% to 4.2% of the power generation amount loss.

· Outdoor transmission line uses temperature resistance 90 degrees Celsius' cross-linked polyethylene insulation layer 4 square millimeters pure copper direct current wire, at 60 degrees Celsius' high temperature sun exposure under, cable's resistance increase value per meter not exceeds 1.5 milliohms.

Diligently clear accumulated snow

5 centimeters thick's dry snow layer will block 95% of sunlight rays, making a unit 5 kilowatts system's daily power generation amount from 20 degrees plummet to not enough 1 degree. When containing moisture, wet snow accumulates to 10 centimeters thick, per square meter, the panel needs to bear 20 to 25 kilograms' extra static load. This kind of heavy pressure, if continuously acts exceeding 72 hours, will lead to a 1.2-millimeter thick aluminum frame bending 2.5 millimeters, the internal silicon wafer will bear microscopic stress, producing a width of about 0.05 millimeters' crack.

· Procuring a root carrying 60 centimeters wide soft silicone squeegee's 4 meters long telescopic pole, single time cleaning's consumable depreciation fee not reaches 2 yuan, and glass surface's scratch rate is 0%.

· Accumulated snow thickness reaches 3 centimeters, the time conducting pushing snow operation's resistance is smallest, once accumulated snow melts after re-freezing into a 5-centimeter thick ice layer, pushing away needed physical pushing force will increase 3 times.

· Putting installation tilt angle set at 40 degrees, when daytime environment temperature returns to 2 degrees Celsius above time, 80% of accumulated snow will slide down automatically under gravity action in 2 hours.

Avoid lightning strike

One time local's lightning strike will in 0.1 seconds inside produce as high as 100 kiloamperes' instant surge current, can in 10/350 microseconds' pulse cycle inside burn down inverter's maximum power point tracking circuit board. Putting all exposed metal modules in contact with an equipotential connection, establishing a strip impedance approaching 0, can put 99% of lightning surges safely into the soil inside.

· Using cross-sectional area being 16 square millimeters' bare copper wire series connecting all aluminum guide rails, connection point uses 6 millimeters specification's stainless steel grounding clip fixed firmly.

· Putting a root length being 1.5 meters' copper-clad steel grounding pole vertically driven into containing water amount 20% soil inside, using a multimeter measured's overall grounding resistance numerical value absolutely cannot exceed 4 ohms.

· At the direct current combiner box, internal parallel installing a piece of 2-level direct current surge protector, ensuring that induced lightning intruding time, can in 25 nanoseconds' extremely short time inside release 40 kiloamperes' nominal discharging current.

Installation Quality Inspection

Look for cracks

At single piece weight reaching 28 kilograms' 550 watts solar panel transporting and going onto roof's process inside, as long as happening 15 centimeters height's dropping or worker applies exceeding 30 kilograms' local pressing, originally thickness only being 0.16 millimeters' silicon wafer internal then will produce naked eye unable to perceive's microscopic fracture. Construction team at night completely no illumination's condition under, must use high resolution EL infrared tester toward whole set system conduct 100% power on scanning.

Giving every string module reverse inputting 10 amperes' direct current after, through a photosensitive camera capturing wavelength at 1,000 to 1,100 nanometers between' infrared luminescence image, once discovering a single piece cell on exists length exceeding 2 millimeters' black stripe, represents a hidden crack already formed. Carrying 0.2 millimeters initial hidden crack's module grid-connected running 6 months after, crack will following 50 degrees Celsius' day night temperature difference brought's thermal expansion cold contraction enlarge to 5 millimeters, leading to that piece panel's output power produce 3% to 5% attenuation.

At noon, 12 o'clock, light irradiance reaches per square meter 800 watts time, again use carrying thermal imaging lens's drone conduct temperature inspection. If the same one-piece panel on any two points' surface temperature difference value exceeds 15 degrees Celsius, explains the internal bypass diode already being forced to start, local hot spot effect is consuming generated's electric energy, corresponding module must with 0 tolerance's principle full amount return exchange.

Check insulation

Direct current side cable's running wire standardization and joint sealing degree decided the whole set system for the next 25 years whether electricity leaking catching fire accidents will happen. Site acceptance personnel needs to use a 1000-volt range insulation megohmmeter, at positive and negative pole cable toward ground, apply direct current high voltage, keeping the test state 60 seconds, read the insulation resistance absolute numerical value cannot be lower than 1 megohm. If the numerical value only has 0.5 megohms, explains the outer layer thickness being 0.8 millimeters' cross-linked polyethylene insulation skin at threading pipe time being scratched broken, encountering relative humidity reaching 85%'s rainy day, then will produce 10 to 30 milliamperes' leakage current, leading to the inverter immediately stopping the machine reporting an error.

All photovoltaic dedicated's MC4 connectors must use hydraulic wire crimping pliers to apply 2.5 tons' pressure to conduct physical crimping, and the joint pressed tight after's anti-pulling force needs to pass a 300 newtons' physical pulling force test and not loosen dropping. Using a micro-resistance tester, measure the docked well's MC4 plug. The contact resistance's reading must be controlled at 5 milliohms below, otherwise, at transmitting 13 amperes' working current, the joint place's temperature will be compared to the environment temperature high out 40 degrees Celsius.

Cable passing through 90-degree wall corner bending time, bending radius must be greater than cable outer diameter's 4 times, toward cross-sectional area 6 square millimeters outer diameter being about 7.2 millimeters' direct current wire, bending radius at least needs to reserve 30 millimeters, preventing internal multi-strand tinned copper wire stress breaking.

Buckle firmly

Aluminum alloy bracket and fixing pressing block's installation torque deviation will lead to whole piece array in 30 meters/second's big wind inside produce per square meter 20 millimeters above's displacement deformation. Worker every one piece tightened used's M8 specification 304 stainless steel bolt, all must use preset well parameter's mechanical torque wrench to conduct final verification, dial on's reading needs to accurately fall at 18 to 22 newton·meters between. If torque is only 10 newton·meters, experiencing 100 times above's level 5 gust small amplitude vibration after, nut will in 3 months produce 0.5 millimeters' loosening gap; if torque is forcedly pulled to 30 newton·meters, 35 millimeters thick's aluminum alloy frame will be pressed out depth 1 millimeter's concave trace, destroying the internal silicone sealing layer.

In order to deal with summer's high 60 degrees Celsius environment temperature difference, every paving as long as 6 meters' aluminum main guide rail, then must at the connection place reserve out 20 millimeters' thermal expansion cold contraction gap, preventing guide rail expansion squeezing leading to panel produce upward 3 millimeters' bow shape bending. Roof load-bearing hook's draft depth needs to reach load-bearing wooden beam internal 60 millimeters, toward single piece hook applying 1.5 kilonewtons' vertical upward pulling force, happened's maximum displacement amount must not exceed 2 millimeters, ensuring every piece panel's 4 pieces force-bearing points are able to evenly share 130 kilograms' limit wind pressure pulling lifting force.

Verify real machine

System grid-connected starting after 72 hours is uninterrupted test running's data verification period, inverter's output end needs to connect a unit high precision's electric energy quality analyzer conducting real-time sampling. At daytime illumination irradiance stabilizing at per square meter 1000 watts' standard test condition under, the system will convert direct current into alternating current and send it into the power grid. At this time, the inverter's maximum power point tracking (MPPT) efficiency must maintain at 99.9% above, and the overall conversion efficiency must not be lower than 97.5%. Input end configured's three groups photovoltaic strings, if every one string accesses all are 10 pieces 550 watts' modules, at the same illumination under's open circuit voltage reading should be at 415 volts around, three pieces loops between's voltage difference value absolutely not allowed to exceed 5 volts.

If the first string voltage is 415 volts, the second string only has 370 volts, explains second string inside at least has one piece panel connected reversely or MC4 terminal exists serious empty connection. Electric energy quality analyzer collected alternating current end data inside, output voltage needs to stabilize at 230 volts, allowed's up and down fluctuation amplitude is positive negative 10%, output alternating current's frequency must be locked at 50 hertz, frequency deviation controlled at positive negative 0.5 hertz within. 10 kilowatt system if at noon 12 o'clock's actual measured peak output power is only 8.5 kilowatts, namely power loss reached 15%, the whole project cannot sign to receive, construction party must one by one troubleshoot and replace line loss exceeding 2%'s cable.