Why Choose Polycrystalline Solar Panels | Efficiency, Durability

Polycrystalline silicon solar panels cost about 15% lower, conversion efficiency about 15%–18%, high temperature resistance performance is better, suitable for large area installation, maintain 30° tilt angle during installation and clean regularly to improve power generation efficiency.

Efficiency

Conversion Performance
Currently, mass-produced polycrystalline silicon solar cell conversion efficiency generally maintains in the 17.5% to 19.2% range. Under 1,000W/m² air mass AM1.5 standard test light source, and cell surface temperature constant at 25 degrees Celsius, one area is 1.63 square meters 60-cell encapsulated poly module usually can output 270W to 290W DC power.

· Manufacturing process middle, silicon wafer surface will plate one layer thickness about 70 nanometers to 90 nanometers silicon nitride anti-reflection film, make specific wavelength between 400 nanometers to 1100 nanometers range light's surface reflectivity forced lower to below 5%.

· Module internal fill factor measured value is usually 75% to 78% between fluctuation, circuit series resistance is generally controlled within 0.5 ohms, parallel resistance then needs to be strictly greater than 500 ohms, through this set of parameters to guarantee continuous output current's stability.

· Single piece side length 156.75 mm size regular polysilicon wafer, in short circuit physical state under's current output ability is about 8.8 amperes to 9.2 amperes, open circuit voltage value can reach 0.63 volts to 0.65 volts.

Temperature Fluctuation
When outdoor actual work environment deviates from 25 degrees Celsius lab constant temperature baseline, polysilicon module's peak output power temperature coefficient is usually calibrated at -0.38%/C to -0.41%/C between. In summer noon direct sunlight environment under, module glass backplate surface physical temperature often will climb to 60 degrees Celsius to 65 degrees Celsius, leading to whole piece panel's real-time output power compared to rated nameplate data large drop 13.3% to 16.4%.

· Open circuit voltage's fixed temperature coefficient generally maintains at -0.31%/°C, panel temperature every increase 10 degrees Celsius, single piece poly module's output voltage will reduce about 1.2 volts, leading to system end's whole string total voltage following it drop about 15 volts to 20 volts.

· Short circuit current temperature coefficient presents positive micro-increase physical state, specific value about falls at +0.05%/°C, panel temperature every rise 1 degree Celsius, output current only weakly increases about 0.004 amperes to 0.005 amperes.

· Under wind speed constant at 1 meter/second, external environment temperature 20 degrees Celsius, sunshine radiation intensity 800 watts/square meter nominal cell operating temperature test condition, poly panel's actual physical operation temperature usually falls between 43 degrees Celsius to 47 degrees Celsius.

Weak Light Power Generation
In the morning 7 to 8 or evening 17 to 18 time period, solar radiation intensity usually will suddenly drop to 200 watts/square meter, poly panel this time's relative photoelectric conversion efficiency still can reach 1000 watts/square meter standard strong light under efficiency value's 95% to 96%.

· Encounter continuous cloudy rainy weather, diffuse reflection type light occupies total input beam 80% above, this time one rated power 300W poly module still can maintain about 25W to 40W weak real-time power output.

· As long as the module end provided DC voltage cross grid-tied inverter set 120 volts to 150 volts physical startup threshold, the system can then with 2% to 5% extremely low load operation rate start toward external grid transport standard AC power.

· Front glass light transmittance is hard required to reach 91.5% to 92%, at the same time, must adopt ultra-white embossed process to treat the surface, to guarantee light incident angle greater than 60 degrees extreme tilt irradiation condition, still have 85% above photon amount can penetrate thickness 3.2 mm tempered glass direct reach silicon wafer internal P-N junction place.

Yearly Degradation
Put into commercial use first year within, poly module received material own light-induced degradation effect's direct influence, system actual output power will appear 2.0% to 2.5% irreversible physical decline. From grid-tied after 2nd month to 12th month, poly silicon wafer internal boron-oxygen complex will continuously consume about 1% to 1.5% internal minority carrier lifetime.

· After the first long as 12 months fast degradation period, in the subsequent 2nd year to 25th year period, every year's linear actual power degradation rate will be strictly controlled at 0.65% to 0.70% fixed downward slope range.

· When a photovoltaic system runs continuously for 10 years, a single piece panel measured output power needs to be based on contract guarantee not lower than factory nameplate calibrated total power's 90%.

· Continuous run to 25th year design life cycle end time, comply with IEC61215 factory standard qualified polysilicon products, its remaining actual power generation must maintain initial promised power's 80.7% to 82% between.

· In simulate potential induced degradation extreme environment test, place poly panel in 85 degrees Celsius absolute high temperature, 85% air relative humidity closed environment chamber, and continuously apply a negative 1000 volts DC bias voltage continuous bake 96 hours, final measured total power loss percentage needs to be controlled in a 5% tolerance range.

Shading Loss
In order to prevent bird droppings or fallen leaves from bringing a local physical shadow effect, one piece contains 60 pieces series connected cells poly module will at back junction box internal parallel connect 3 rated load current as 15 amperes or 20 amperes silicon material bypass diodes.

l When the panel front has 10% physical area covered by a non-transparent object for 30 minutes, the local silicon wafer surface temperature will because of the hot spot effect rapidly climb to 120 degrees Celsius to 150 degrees Celsius.

l This time, the internal one of the bypass diodes will conduct rapidly within 0.01 seconds, take 20 pieces covered series cells from the circuit forcibly cut off, leading to the whole piece poly panel's instantaneous output power appearing a 33.3% cliff-like drop.

l If not have these 3 bypass diodes' physical intervention, the covered part resistance value will suddenly increase 50 times to 100 times, causing the whole string photovoltaic DC string's transmission current to plummet 80% above.

l System early stage design time strictly required front and back two rows PV array horizontal physical distance maintain at 2.5 meters to 3.5 meters, ensure in every year Winter Solstice day morning 9 to afternoon 15 these 6 hours solar height angle lowest irradiation range within, not have any exceed 0.5 square meters building or vegetation shadow project to panel bottom 5 cm height above effective power generation area.

Durability

Can Bear Hit

Poly silicon module outermost layer covered one layer thickness reaching 3.2 mm low iron tempered ultra-white embossed glass, light physical transmittance maintains in 91.5% to 92.2% range. In a lab environment under hail physical impact standard test, pneumatic launch equipment will one diameter 25 mm, weight about 7.53 g solid ice crystal ball, with 23 meters/second physical terminal speed (equal to hourly speed 82.8 km) launch and vertical impact panel front 11 different designated physical coordinate points, after continuous impact, glass surface layer not allowed appear any naked eye visible physical fracture or depth exceed 0.1 mm tiny crack.

In the destruction stronger steel ball drop experiment, one weight 227 g standard solid stainless steel ball from 1000 mm vertical absolute height free fall hit toward the glass center area, panel internal upper lower two layers thickness distributed in 0.45 mm to 0.6 mm between EVA film will rapidly happen deformation, absorb 90% above mechanical impact kinetic energy, guarantee located at encapsulation structure middle layer thickness 180 micron polysilicon cells not happen large area micro-cracks or physical grid break phenomenon.

Blow Wind Fall Snow

Poly panel periphery adopts cross section thickness of 35 mm or 40 mm anodic oxidized aluminum alloy frame proceed whole surround physical press, surface oxide film thickness is strictly controlled by factory between 15 micron and 20 micron, specially used to block long-term exposure to outdoor air middle metal material happen irreversible oxidation corrosion.

In the mechanical static load test chamber inside, the panel front needs to bear a high as 5400 Pascals downward physical pressure, equivalent to every 1 square meter surface area evenly shared thickness exceeding 1.5 meters, total weight reaching 550 kg static accumulated snow, load state under panel center's physical deflection deformation amount must be smaller than its long side total size's 1.2%, after removing external load need in 2 hours within completely recover physical flatness.

The panel back side similarly needs through 2400 Pascals dynamic wind load back and forth pull test, equivalent to at system installation tilt angle set as 30 degrees, module can resist wind speed reach 130 km/h 12-level strong gust toward outside pulling, on installation bracket cooperate use torque set in 14 Newton-meters to 18 Newton-meters range M8 model stainless steel fastening bolts, can take whole set panel's physical displacement rate firmly lock in 0.5 mm extremely small error range within.

Alternating Cold and Heat

In simulate extreme climate violent change TC200 thermal cycle test process, the poly panel will be whole pushed into a closed walk-in environment chamber. The chamber internal gas temperature needs to be between minus 40 degrees Celsius and plus 85 degrees Celsius continuously proceed 200 complete physical high-low temperature alternating cycles, period maximum cooling and heating physical rate requirement reach every hour change 100 degrees Celsius.

In the DH1000 damp heat accelerated aging test project, test equipment requires taking panel place in a temperature constant at 85 degrees Celsius, air relative humidity high as 85% high pressure airtight space inside continuous bake place 1,000 hours, test period full after extract panel measure internal circuit series resistance, resistance increase amount must not exceed initial set resistance 5%, and whole piece poly panel DC output power maximum loss percentage forced limited in 5% tolerance red line within.

Moisture Proof and Salt Alkali Resistance

Backplate back use silicone glue bonded junction box shell by high strength polycarbonate material injection molding, solid dust and liquid water physical protection level calibrated as IP68 level, can at underwater 1.5 meters static water depth middle continuous soak 24 hours without happening internal circuit short circuit, box body inside poured thermal conductive silicone take 3 rated load current 15 amperes or 20 amperes bypass diodes completely physical seal dead, ensure diode at 110 degrees Celsius extreme work high temperature under can take accumulated heat rapidly conduct diffuse to external air in.

Bottom connect inverter equipment two standard lengths as 900 mm, cross-sectional area 4 square millimeters tin-plated pure copper core DC cables, outer layer tightly wrapped through UV anti-aging treated cross-linked polyolefin insulation layer, in concentration ratio as 5% sodium chloride neutral salt spray solution continuous spray 96 hours corrosion penetration test in, cable outer skin insulation layer will not crack, and circuit insulation resistance value can maintain at 400 Megohms above high level.