光伏行业中经济有效的冷却方法

THERMAL MANAGEMENT OF PV: COST EFFECTIVE COOLING METHODS SNEC 13th (2019) International Photovoltaic Power Generation and Smart Energy Conference & Exhibition Industry Workshop on High Efficiency Solar Cells, Auxiliary Materials and Technologies Related June 4th 2019, 17.00-17.15 Thermal management of PV modules increases in importance: ▪ Temperature losses average 11% - more than AC/DC loss, dirt & dust loss ▪ Strongest growth of large scale solar in high temperature areas (tropical/desert) ▪ Thermal load of the cells increases due to optimized tracking system use HEAT LOSSES INCREASE STC output measure in flashtest at Tcell of 25 oC, irradiation 1.000 Watts/m2, AMN 1,5 2 Besides STC and NOCT standards and measurements, thermal management is generally ignored. NOTC measuring Tcell at 800 Watts/m2, Tambient 25 oC, wind 1 m/s, mostly around 40- 50 oC HEAT LOSSES EXPLAINED The effect of higher temperatures at the moderate working range is a drop of 6-7% in efficiency, or the equivalent of approximately 20 Wattpeak per 60-cell module The effect of high temperatures on degradation/ lifetime is not included in standard IEC tests TEMPERATURE v EFFICIENCY FOR A Si SOLAR CELL 3 Cell temperatures are however not maximized to 60oC, not even in moderate environments where they can measure 70oC or more, while they easily reach 80-90oC in desert & tropic regions. This is dT of 60-70oC above STC, losing 20% output. T-AMBIENT IN oC 35o 25o 15o T-CELL IN oC 60o 40o 20o 80o HEAT LOSSES OFTEN UNDERESTIMATED DATA FROM A SINGLE DAY (Sevilla, Spain- May 2019) 4 Several attempts and technologies have been tested since the 1980’s: All options remain small scale as they do not fit standard PV product or production, they add weight, add costs and most of them have limited effect on cooling. PHASE CHANGING MATERIALS COOLING RIBS - MASSIVE ALUMINUM PV THERMAL, WATER- COOLED SYSTEM PREVIOUS COOLING ATTEMPTS 5 New approach by COOLBACK Company: R&D with minimal (but optimal) material use. Considering: measurement errors (IR failures, Thermocouple, Module/Cell) in temperature are only useful for comparison. For yield, the most accurate measurement is open circuit or real output (Watts) by sensitive instruments. NEW COOLING APPROACH FRAMED MODULE FRAME + COOLBACK UNFRAMED + COOLBACK 6 Cost effective cooling is obtained by substituting materials, not adding them. Re-designed and integrated frame, together with a rib design that optimizes airflow and support, promotes cooling for NO additional costs. COST EFFECTIVENESS = COST SUBSTITUTION FRAME = BARRIER COOLBACK = PROMOTER 7 1. Mechanical design standpoint only 2. Disputable cooling effects, edge only 3. Frame blocks and locks-in heat 4. Height & form limit stacking options 5. No functional integration with module UPGRADED FEATURES FOR FRAME 1. Mechanical + support + cooling design 2. Large surface for powerful cooling 3. Unobstructed air flow for heat removal 4. Nesting = stacking volume & costs 5. Integrated with backsheet & mounting 8 Standard Framed Module A frame replacement with increased surface area on a module’s backside has been studied under several conditions, with varying altitude, irradiation, wind and temperature. Test locations: Italy, Spain, Qatar & The Netherlands PV module comparisons: mono-, poly, H- pattern and back- contact technology Shape and airflows are basis of final designs and testing. THERMAL EFFECTS - SIGNIFICANT & STABLE 9 Effect of lower temperatures at tracking implemented in design. LOWER TEMPERATURES source: KIWA - springtime, Northern Italy 10 LANDSCAPE ORIENTATION The kWh output effect, already in fixed tilt, is significant – also at moderate temperatures. The lower temperature (in everyday/ thermal cycle) reduces degradation, prolonging lifespan. HIGHER OUTPUTS source: KIWA, Spain – springtime PEAK : 13.00-14.00 SUN : 985 W/M2 PEAK AT : 13.00-14.00 EXTRA % : +8,6% COOLBACK® MODULE REFERENCE MODULE WA TT S 11 T-AMB : 29,40o C T-REF : 68,90o C DAY AT : 08.00-19.00 EXTRA % : +5,5% Wind, ambient temperature and, mainly, irradiation have an effect on output performance of PV modules. Predicting cooling gains per location is possible by measuring the temperature of the reference (= standard) module. COOLBACK® yields an additional 1,4% extra output per 10oC above 35oC. Valid up to 4,5 m/s windspeed. LOWER HEAT LOSSES ARE PREDICTABLE 12 Footnotes: ▪ COOLBACK® creates extra Watthours, no extra Wpeak ▪ NO influence on module ($/Wp) prices, due to frame substitution – possible when produced with (automated) production. Retrofitting is not a cost- effective option Installation: ▪ Field or flat roof: sufficient ventilation is required IMPORTANT FOOTNOTES & FOLLOW-UP 13 Lifetime: ▪ COOLBACK® has a positive effect on temperature and stiffness: both influence the real thermal cycling and therefore the aging of materials. Further research and results will be available in future presentations (including SNEC Workshop) Availability: ▪ 4 module manufacturers supply COOLBACK® equipped modules, more to follow soon