Efficiency Improvement Module Technology Research-GCL

Wang Guofeng, GCL Aug 3rd 2018 PV Module Efficiency Improving Technology Research GCL: the biggest comprehensive clean energy industry platformGCL has made three times of strategic transformation during its development history and thereby occupy an advanced position in clean energy field The group owns several listed companies: Poly GCL (3800.HK): global biggest polycrystalline 2. Use reflective welding strip/pad pasting processPower loss owing to internal istance of inter-link/bus-bar 1. Reduce welding strip resistanc; 2. Use MBB, half-chip etc to reduce resitance losslight transmission thru the gaps between chips and serials Use white EVA etc to increase light reflection Effect of improved light transmission on power gainØ Experiment design Use identical materials for all module parts but for glass, and verify the effect of light transmission of the glass on CTM. The result is shown below: use of high transmission glass may improve CTM by 0.8% at most. Ø Experimental results: 1. By using identical materials for other parts, transmission of glass is directly relating to CTM; 2. To increase light transmission of glass is an effective mean to improve module CTM; 3. Light transmission difference between more widely used PV glass types may cause 0.8% CTM difference. Effect of white EVA on power gain Ø Theory of power increment by use of white EVA White EVA is of higher reflection than traditional rear panel or glass, so that the module power can be increased by using the gap between serial chips to improve resuse of the light energy. Ø White EVA power gain: GCL bulk product data verification White single-glass module power gaied in by 0.7% White dual-glass module power gained in bmore than 2% Effect of weld strip resistance on power gain Ø Effect of welding strip resistivity on power rate Power loss by welding strip P=Impp²*R=Impp²*ρ*L/S, so that the strip resistivity is directly proportional to loss, use of low resistant strip may bring up to 0.7% of CTM increase. Ø Experiment design: Use entical materials for all other parts but for welding strp of different resistivity, the power comparison test ontained following result: Ø Experimental results: 1. By using identical materials for her parts, weld strip resistivity was found reversely proportional to CTM2. Reduction of weld strip resistance can effectively increase module CTM, use of low resistance strip may result in a CTM difference of up to 0.7% Effect of relective weld strip/pad pasting on module power rate Ø Theory of CTM increase by reflective strip/film pad Deeper trough on weld strip surface will increase diffuse reflection and hence the current and module power rate. It was verified by GCL bulk product data that: relective strip and pad film can increase CTM by 0.8% and 1.7% respectively over those of regular type of strip. EVACellBacksheetGlassØ Comparison of surface structure and reflectivity Reflective weld strip LRF reflective film Regular weld strip Contents Module efficiency improvement by best packaging technologySelected auxiliary material helping module efficiency improvementGCL technology 2) can use much finer wire to reduce silver consumption; 3) can further decrease main grid resistance and contact cell to reduce heating loss; 4) will greatly improve defect (sub-fissure) tolerance oery chip; 5) can reduce hot spot risk and truly guarantee power generating capacity retention. 2BB 3BB 4BB 5BB 12BBMulti-grid technology features: ü Finer and thiner main/aux grids for less use of slurry and cost downü Circular copper weld strip of ＜0.4mm dia. for increased reflection and enlarged light areaü Shorter path of current collection to reduce effect of sub-fissure on battery performance and increase toleranceü Cost down from battery end in addition to improved power CTM and higher reliability 1. MBB multi-grid packaging process -- featurs & advantages MBBtechnology features Cost-down by less use of silver slurry Short currnet collection path for higher efficiency Much better appearance Better sub-fissure tolerance & reliability Circular weld strip to increase reflectionHighly compatible half-chip hi-effi battery MBB multi-grid packaging process -- featurs & advantagesØ Power gain of 12BB is 0.2%～0.25% higher than 5BB, total power increase will be around 5W for the whole module MBB multi-grid packaging process -- battery efficiency simulation Efficiency data simulation for different number of grid wires: 1. 12BB battery efficiency can be improved by 0.2%～0.25% over 5BB, showing around 5W gain for whole module2. 9BB efficiency gain is 0.02% less than 12BB. 3. Best design needs to take slurry consumption, efficiency gain, module gain and cost-down in acountNumber of wires Longest transmission path 4BB 19.5mm9BB 8.4mm12BB 6.2mm Ø MBB module reliability test and high severity test show much less power decay than IEC standard (-5%), showing the product can meet long term outdoor use conditions Ø Increased sub-fissure tolerance and less effect of sub-fissure on power output MBB multi-grid packaging process -- long term reliability Weld spot full and not offset Weld spot full but offset Weld spot small, not offset Uneven solder resulting in rosin weldWeld strip layout accuracy match with weld disc design Ø Too small disc may cause strip offset, resulting in rosin weld or partial welding. Ø Bigger disc can reduce partial welding risk to achieve better weld performance but cause higher silver slurry consumption. Optimal design of disc size and tin solder thickness can achieve satisfactory pull stress at both front and rear faces of the weld disc. MBB multi-grid packaging process industrial application -- improved weld performance Through equipment modification & material improvement, one-pass MBB premium quality product rate has been elevated gradually and is expected to approach the level of regular module types. MBB multi-grid packaging process industrial application -- stepwise increasing premium quality product rate Description Capacity/beat Quantity Chip cutter/serial welding integrated package 2400pcs/h (integral) 3200pcs/h (half chip) 12 Typesetter 60pcs/h 12 Stack welders A/B 25S 3 packagesPost equipment Regular types Matched capacityØ Integral Ø Half-chip Ø Dual glassØ Mono-/polycrystallineHigh compatibility Ø Chip-cutter/serial welding integration: one man/machine post omittedØ Bus-bar automatic welding: 4 man/machine posts omitted Less labor demand MBB multi-grid packaging process industrial application --500MW process line put in operation MBB multi-grid packaging process industrial application -- 300W+ module power distribution Polycrystalline 60pcs module 300W technology combinationØ GCL diamond wire hi-effi black Si PERC, combining with MBB technology, averaged battery efficiency exceeds 20.8%Ø MBB module CTM＞98%Ø Main stream grade 295W+ modules account for ＞96%, the proportion of 300W+ exceeds 56% 2. Half-chip module packaging process -- featurs & advantagesØ Half-chip design can increase CTM by 2.5%.• 电池片面积减半，电流减半，内耗减少3/4• 电池片间距增加一倍，增强零深度反射效果提升组件CTM • 使用分体式接线盒，减少了线缆连接长度，提升组件CTMBattery chip half cutting Increasing zero depth reflection 优势降低了损耗提升功率 低隐裂和热斑风险适合大型地面电站系统兼容60/72和MBB/双面电池等结构设计降低遮挡影响低工作温度提升发电量 Half-chip module packaging process -- typesetting design Ø In Apr 2016, GCL developed a both end leads half-chip module and introduced it in bulk productionØ This half-chip model can increase module power gain by around 2.2%Ø Circuit structure on this model module needs to add dummy insulative lines to isolate the junctions, but causes less change in operation comparing to that of regular module. Ø Two typesetting design models of half-chip packaging result in 0.3% of CTM difference. Ø In Sep 2017, GCL started to develop and introduce middle lead half-chip model. Ø This half-chip model can increase module power gain by around 2.5%Ø This model is of simpler circuit structure but needs to develop a new type stack welder. With developed equipment the model is now fully fit to bulk production, and has become a main stream half-chip type in the industry. Half-chip module packaging process -- practical power generation test Ø Geographic location Nanjing (E : 118 ℃ 46 , N: 32 ℃ 03 )Ø Installation capacity: 50 KWØ Module models Half-chip P3/72, integral chip P6/72Ø Testing method Comparing the models of same code number and same power rate. Ø Conclusions 1. Comparing to integral regular module, power output gain is about 4.5% 2. Under climate conditions of high temp and strong sunshine, half-chip module will enjoy significant power output advantage. Note: during the time period of 7.16-7.29, one of dual-chip modules failed to turn round owing to tracking support troble, resulting in less power output from the module. 3. Dual-face dual-glass module packaging process -- featurs & advantagesØ Dual-face dual-glass module has both the advantages of dual-face and dual-glass options. Ø Under different situation, the rear face may add 5%-30% of power output. Ø Dual-glass design, 30-year power rate warranty, annual decay rate of 5% fromthe secod year and on. Ø Dual-face output&1500V systemvoltage for lower system BOS and LCOE (kWh cost) Ø Compatible with MBB and half-chip process High output High reliability Low LCOE No side-frame design, free from snow/dust accumulationHigher reliability passing through triple IEC ageing test Friction resistant, fit to desert area installationLow moisture permeation, free of PID and snail stripe risk, best fit to water surface/wet surrounding installation High fire-proof grade, class ALower risk of sub-fissure and hot spot