#1go PV This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 792059 Oct. 27th PV Modules: Bifacial technology (14:30-16:30) GLOBAL OPTIMIZATION OF INTEGRATED PHOTOVOLTAIC SYSTEM FOR LOW ELECTRICITY COST Daniel Valencia, TECNALIA Paul Berthelemy, CEA INES + in#2tecnalia Inspiring Business go PV PV Modules: Bifacial technology 7.1.1 Index of the session . 14:30 - Introduction to bifacial technology [D. Valencia - TECNALIA] • 14:50 Current status of bifacial technology [D.Valencia - TECNALIA] • • 15:05 - Bifacial modules developed in GOPV project: beyond the market status [Paul Berthelemy - CEA] 15:40 - 15 min BREAK 15:55 - Bifacial PV production software options [D.Valencia - TECNALIA] 16:05 - Bifacial PV production: practical case [D.Valencia - TECNALIA] GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#3tecnalia Inspiring Business go PV PV Modules: Bifacial technology 7.1.1 Index of the session • 14:30 - Introduction to bifacial technology [D. Valencia - TECNALIA] • 14:50 Current status of bifacial technology [D.Valencia - TECNALIA] • • 15:05 - Bifacial modules developed in GOPV project: beyond the market status [Paul Berthelemy - CEA] 15:40 - 15 min BREAK 15:55 - Bifacial PV production software options [D.Valencia - TECNALIA] 16:05 - Bifacial PV production: practical case [D.Valencia - TECNALIA] GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#4go PV Introduction • Key Ideas Monofacial PV: only frontside of the photovoltaic (PV) module produces electricity using incident solar radiation. Traditional concept. Bifacial PV: both frontside and backside of the photovoltaic (PV) module produce electricity from solar incident radiation. • Compared to monofacial, bifacial PV technology have an additional electricity production thanks to extra radiation received at the backside. . The cost of bifacial PV modules are slightly higher. Also some additional expenses are required by bifacial PV plant. The extra production normally compensates the extra cost. However, every case should be analyzed in detail. tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#5go PV Key Ideas Introduction "Bifacial solar modules, which generate power on the front and back, is the technology that will help bring down LCOEs of solar power plants the most in the short-run. This results in power gains between 5% and up to 30%, depending on the solar cell technology used, location, and system design." Bifacial Module Technology 100% 90% 80% LCOE = SolarPower Europe Installation+operation cost Total energy produced World market share [%] tecnalia Inspiring Business 70% 60% 50% 40% ITRPV 2020 30% 20% 10% 0% 2019 2020 not bifacial 2022 2024 2027 2030 bifacial Global Market Outlook For Solar Power/2020 - 2024 ITRPV 2020 Report. Oct 2020 GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#6go PV • Key Ideas Introduction Since about 2012, interest in bifacial PV has been constantly increasing • • • Some of the new solar cell technologies, which are currently being implemented in industrial production, allow a comparatively simple adaptation to a bifacial layout General trend towards glass/glass modules with superior reliability A major issue is the uncertainty regarding the additional 'bifacial' yield, which is due to the more complicated irradiation conditions and the power rating of bifacial modules. Standardized measurement conditions for bifacial modules published in 2019: IEC TS 60904-1-2 Starting from today's 12% bifacial market share the ITRPV roadmap 2020 predicts an increase to around 33% by 2027. Bifacial Module Technology World market share [%] 100% 90% 80% tecnalia Inspiring Business 70% 60% 50% 40% ITRPV 2020 30% 20% 10% 0% 2019 2020 not bifacial 2022 2024 2027 2030 bifacial ITRPV 2020 Report. Oct 2020 GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#7go PV Introduction Utility scale PV Integration LCOE reduction due to backside production Fixed systems or 1- axis tracking New applications and products More production per m2 with low cost increase Combined uses: Agro-PV and Floating PV Better use of soil for PV and agriculture More production in floating PV tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#8go PV Introduction New parameters that impact on bifacial extra production Bifacial ratio: • • Irradiation ratio received by the backside of the modules compared to frontside of the module during one period time (hourly, monthly, yearly ...). Depends on module installation parameters, ground albedo (i.e. ground reflection) and irradiation conditions (direct or diffuse). Module bifaciality: Bifacial Ratio = Gback Gfront • The backside of the bifacial module is not as efficient as frontside. • • Is the ratio of backside module peak power compared to the front side. Depends on mainly PV technology. It is normally indicated in module datasheet. • Bifacial Gain: .• Module Bifaciality: = Pmpp back Pmpp front Energy gain increase due to backside electricity production compared to the front side Eback Bifacial Gain = Bifacial Ratio * Bifaciality Efront tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#9go PV Introduction New parameters that impact on bifacial extra production G Beam Albedo soil Soil reflection Albedo modules Bifacial PV Tracking: The Simulation and Optimization of Yield Gain. Soltec webinar. Apr 2018 Gpif Diffuse module reflection Grear Gdiffuse + Greflected (albedo) G° G° global global FRONT ALBEDO ...-- TRACK G. front BEAM E E front rear E. bifacial DIFFUSE BEAM DIFFUSE REAR G rear bifaciality ALBEDO tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#10go PV Introduction Bifacial Ratio (BR) - Irradiation at the backside • Gback Bifacial Ratio Gfront tecnalia Inspiring Business Albedo is the diffuse radiation reflected by the soil out of the total solar radiation. Normally goes from 10% to 40%. Higher albedo means higher BR. It strongly impacts the bifacial ratio with nearly linear behavior. • Row-to-Row spacing (aka pitch) is the distance between rows. BR increases when this distance increase. It is related with GCR (Ground Coverage Ratio). . Clearance height is the distance between the bottom of the modules and the ground. Higher clearance means higher BR. • Tilt of the modules also affects the BR value. Albedo Row-to-row spacing Clearance Tilt Material Asphalt Light soil Concrete Beige built-up roofing White EPDM roofing Reflectance*(R) Grear at 1000Wm-2 front 0.1 70 Wm-2 0.21 130 Wm-2 0.28 170 Wm-² 0.43 250 Wm-² 0.8 430 Wm-² Deline et al., IEEE PVSC 2016; Deline et al., IEEE JPV (submitted) (National Renewable Energy Laboratory) GOPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#11Bifacial Ratio % (BR) 30 50 25 20 L 19 go PV Introduction Green grass varieties Gback Bifacial Ratio (BR) - Irradiation at the backside Bifacial Ratio Gfront Desert sand Influence of albedo % 30 40 50 60 70 80 90 Albedo % Pitch 40 ft Pitch 33 ft Pitch 26 ft 12 m 10 m 8 m Pitch Distance between trackers - Snow Bifacial Ratio % (BR) 10 30 25 20 15 Influence of pitch % GCR 0.4 GCR 0.33 8 mi 9 m 10 m 26.2 ft 29.5 ft 32.8 ft 11 m 36.1 ft. 12 m 13 m 39.4 ft 42.7 ft. Pitch % Alb 25% (Green grass) Alb 40% (Dry grass) Alb 50% (White sand) Alb 90% (Snow) Wider Pitch Longer Tracking + Better Bifacial Gain Bifacial PV Tracking: The Simulation and Optimization of Yield Gain. Soltec webinar. Apr 2018 Enlarged reflective area Bifacial Ratio % (BR) 19 35 30 25 20 15 10 Influence of height tecnalia Inspiring Business I 2.0 m 6.6 ft 2.2 m 7.2 ft 2.4 m 7.9 ft 2.6 m 28 m 8.5 ft 9.2 ft Height Alb 25% (Green grass) Alb 33% (Dry grass) Alb 50% (White sand) Alb 90% (Snow) GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#12go PV Introduction Gback Bifacial Ratio (BR) - Irradiation at the backside Bifacial Ratio Gfront • Global expected Bifacial Ratio (Modeled Grear /Gfront) • For 1-axis-tracked 2-up portrait systems over natural ground cover. Assumed geometry: GCR = 0.35, h = 3 m. Tracker bifacial irradiance gain [%] Pelaez et al. Model and Validation of Single-axis tracking with bifacial PV. IEEE Journal of Photovoltaics, vol.9, no.3, May 2019. 20.0 17.5 15.0 12.5 10.0 7.5 5.0 2.5 0.0 tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#13go PV Introduction Albedo The albedo of a surface is the fraction of the incident sunlight that the surface reflects. Important measure it. Necessary for the characterization of the results. Albedo may change from season to season: snow during the winter or different vegetation on the ground. Method for measuring albedo described in ASTM E1918-16 "Standard Test method for measuring solar reflectance of horizontal and low-sloped surfaces in the field”. Measurements are not even constant during the day. Constant values (average from measurements) are normally considered for calculations. Monthly values can be considered as well. incident light diffuse reflection specular reflection Source: GIS stackexchange Field Testing Meets Modeling: Validated Data on Bifacial Solar Performance. Kyumin Lee, Array Technologies. BiFi July 2020. Albedo mounting plate H R S tecnalia Inspiring Business Upper screen (white) Pyranometers Lower screen (white) Equator D Mast (black) Albedo measurement construction source: Kipp & Zonen GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#14go PV Introduction Bifacial Ratio (BR) - Edge effects • . Bifacial Ratio is higher near the edge of the PV panel rows i.e. the panels close to the edge will receive more radiation at the backside. This will create mismatch in the electrical circuit Normally, due to electrical connections, the final PV production is determined by bifacial gain at the center of the row Example of bifacial gain study where the main bifacial gain is analyzed in the center of the central rows to avoid edge effects. E N W 5 CFV Labs Data from interior rows only →> Shading patterns on ground representative of utility-scale installations Test arrays on inner seats only → Avoid "edge brightening" at north and south ends N -15m -10m -5m 0 5m +10m +15m S 8% bifacial gain Higher (13%) bifacial gain at north/south ends Image adapted from S. Ayala Pelaez et al., NREL/CP-5K00-72039, 2018 ARRAY FOLLOW THE SUN. TECHNOLOGIES FOLLOW THE LEADER. Pelaez et al. Model and Validation of Single-axis tracking with bifacial PV. IEEE Journal of Photovoltaics, vol. 9, no.3, May 2019. Field Testing Meets Modeling: Validated Data on Bifacial Solar Performance. Kyumin Lee, Array Technologies. BiFi July 2020. Y Position along row [m] tecnalia Inspiring Business H=0.4 BG [%] E H=0.75 BG [%] -15 -15 13 13 -10 12 -10 12 72 11 -5 0 6 5 8 Y Position along row [m] 11 5 10 0 9 5 8 7 7 10 10 6 6 15 15 5 5 -1 0 1 -1 0 1 X Position [m] X Position [m] (a) (b) Yearly cumulative distribution of BGE across the center row of a 20-module x 7-row single-axis- tracking array for (a) H = 0.4 and (b) H = 0.75. BGE is significantly higher (13.9%) at the edges of the row. Radiance simulation. GCR = 0.35, Albuquerque climate. GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS 4 October 26-29th 2020#15go PV Introduction Module Bifaciality Pmpp back Module Bifaciality = Pmpp front tecnalia Inspiring Business Module bifaciality is strongly related with module technology: PERC: Most common. Monofacial manufacturing lines easy to transform to bifacial. Lower bifaciality (70-80%). Usually p-type cells. Probably the cheapest bifacial option. PERT: Quite common but less than PERC. Manufacturing lines transformation more complex than PERC, but still relatively easy. Good bifaciality (80-90%). Usually n-type cells. Relatively cheap but more expensive than PERC. HJT/SHJ: High efficiency, high bifaciality (about 95%). Cell fabrication is very different from that of homojunction c-Si cells. Low temperature coefficient (<0.3% /ºC). Normally more expensive than PERC/PERT. IBC: promising option to obtain high-efficiency solar cells. The contacts are solely on the rear side of the solar cell. This approach requires other fabrication procedures. Still in its infancy. Cell concept Bifaciality factor Si base material Junction and BSF doping method Contacts Heterojunction >0.95 n-mono a-Si:H p-and n-type doped TCO/Ag (Front) Efficiency potential 22-25% Industry TCO/Cu plated PERT >0.90 n-mono p-mono B and P tube diffusion Ag and Ag/Al printed 21-23% 3Sun, Hanergy, Hevel, Jinergy, Panasonic, Sunpreme, etc. Adani, Jinko, Jolywood, LG, Linyang, REC, Trina, Yingli, etc. p-multi n-doped poly-Si rear side possible PERC+ >70% p-mono p-multi B and P tube diffusion, Ag and Al printed local AI BSF 21-23% Eging, JA Solar, Jinko, Longi, NSP, SolarWorld, Trina, etc. n-mono IBC >70% n-mono B and P tube diffusion Ag and Ag/Al 22-25% Valoe State-of-the-art bifacial module technology. printed PVTech September 2018 APCVD doped oxides GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#16go PV Introduction Bifacial Gain Eback Bifacial Gain = = = Bifacial Ratio * Bifaciality Efront • • Bifacial gain is the energy production increased due to backside module extra production Common bifacial gains are in the range of 5% to 10% (albedo between 15-30%). This means that bifacial systems produces between 5% to 10% more energy than equivalent monofacial installation. Higher bifacial gains can be obtained with small prototypes because the backside of the modules have a "better view" of the ground. However the bifacial gain decrease for real PV plants with several and long module rows. Total bifacial gains since inception, per manufacturer Bifacial Gain vs. Time of Day Bifacial Gain Bifacial Gain Grass White Mfr. A 5.57% 8.28% Mfr. B 6.57% 8.78% Mfr. C 7.46% 11.44% Mfr. D 7.23% 10.73% Bifacial Gain (%) 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% - tecnalia Inspiring Business 7:50 8:40 9:30 10:20 11:10 12:00 12:50 13:40 14:30 15:20 16:10 17:00 17:50 18:40 7:30 8:20 9:10 10:00 10:50 11:40 12:30 13:20 14:10 15:00 15:50 16:40 17:30 18:20 7:10 8:00 8:50 9:40 10:30 11:20 12:10 13:00 13:50 14:40 15:30 16:20 17:10 18:00 18:50 Data normalized to pre-light soak flash Example of bifacial gain using different PV modules (A, B, C, D) with two albedo conditions Bifacial Bake-off: Comparing Technologies and Manufacturers. Jenya Meydbray, PVEL. BiFi July 2020. ●Mfg. A Grass/Dirt • Mfg. A White ●Mfg. B Grass/Dirt ●Mfg. B White GoPV Project | 1st TRAINING COURSES 16 TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#17go PV Introduction Other bifacial technical considerations • The extra backside radiation increase the current, similar to an increase of radiation at the front. • • Higher currents should be considered for bifacial systems, specially when selecting the inverter. • The peak power of bifacial systems will be higher, that the AC power (inverters) should be higher as well. tecnalia Inspiring Business The traditional DC/AC power ratio should be close to 1 instead of 1.2. Specific calculations of clipping losses should be performed. • Structural systems backside shadowing should be avoided → specific structural systems • Junction boxes should be smaller in order to avoid shadowing of backside. ... GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#18tecnalia Inspiring Business go PV PV Modules: Bifacial technology 7.1.1 Index of the session • 14:30 - Introduction to bifacial technology [D. Valencia - TECNALIA] • 14:50 - Current status of bifacial technology [D.Valencia - TECNALIA] • • 15:05 - Bifacial modules developed in GOPV project: beyond the market status [Paul Berthelemy - CEA] 15:40 - 15 min BREAK 15:55 - Bifacial PV production software options [D.Valencia - TECNALIA] 16:05 - Bifacial PV production: practical case [D.Valencia - TECNALIA] GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#19go PV . • Current status General PV status Total installed PV systems →650GW Expected installation in 2020 are 105 GW (already reduced with COVID) 1TW PV to come in 2022/23; 30 70TW expected in 2050 Module prices are already below 0.2 $/ Wp S/kWh Solar Power Bids Under $0.02/kWh 0.02 0.0169 0.016 LCOEs below 2 c$/kWh possible (lowest 1.35 c$/kWh) 0.012 Probably LCOEs at 1USct/kWh to come soon with bifacial HSAT 0.008 Standard PERC coming to efficiency limits of below 23% Cost down is now realized by larger wafer sizes (M10/M12) N-type cell concepts are gaining importance • "60 cells modules" are reaching 400Wp • "72 cells modules" are exceeding 500Wp Remarks: Bifacial PV: Chances and Challenges. Radovan Kopecek, ISC Konstanz. BiFi 2020. 0.004 0.01646 0.01567 0.0135 0 900 MW Dubai 150 MW Portugal 800 MW Qatar 2 GW Abu Dhabi TalyangNews tecnalia Inspiring Business GoPV Project | 1st TRAINING COURSES 19 TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#20go PV Current status tecnalia Inspiring Business General bifacial status Bifacial technology offers an increase of energy yield at low additional costs Bifacial PERC technology is at the moment dominating the market; n-type and Ga doped PERCS are coming Better module testing and reliable energy yield simulations required With bifacial HSAT technology we will reach soon bids at and below US$0.01/kWh in MENA region and later also in e.g. in Chile and US* First bid below $0.02/kWh was bifacial HSAT from EDF/Masdar ($0.0179/kWh) in 2017 in Saudi Arabia >> rejected also because bifacial PV was not bankable at that time Status of bifiPV installations until 2020 15C International Solar Energy Total installation of bifacial systems [MW] 20000 18000 16000 14000 12000 10000 HSAT p-type fixed tilt n-type HSAT n/p-type >400MW 8000 >2MW >1MW 6000 4000 >10MW >100MW Research Center Konstanz forecast *Remarks: Bifacial PV: Chances and Challenges. Radovan Kopecek, ISC Konstanz. BiFi 2020. 2000 D 2012 2013 2014 2015 2016 2017 2018 2019 2020 GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#21Front side go PV Current status Module variations • First generation was with traditional aluminium frame and tradition junction box . Half-cells for better performance Frameless: avoid shadowing at the backside of the cells close to the edges → it requires glass-glass instead of glass-backsheet Smaller junction box to avoid shadowing at the backside of solar cells Rear side Bifacial module first generation Bifacial module frameless Bifacial module frameless, shallow junction box Bifacial module frameless, shallow junction box and half cells Front side Remarks: Bifacial PV: Chances and Challenges. Radovan Kopecek, ISC Konstanz. BiFi 2020. Rear side GOPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020 tecnalia Inspiring Business#22go PV Current status Module variations: frameless glass-glass vs framed glass-backsheet . Frameless glass-glass: • Better backside performance as there are no frame that may shadow cells near the edges . Better mechanical performance • • • Glass-glass configuration causer lower degradation rates and module guarantee can be extended Framed glass-backsheet: . Lower weight Less breakages during transportation and installation • Installation can be made with traditional clips. Can save labor cost. There is not a clear winner. Some manufacturers offer both options. Nevertheless some manufacturers recommend glass-glass only for high mechanical loads and/or high humidity applications. • Glass-glass + frame also possible. • Glass-Transparent backsheet without frame not possible due to mechanical requirements. Туре Bifacial with TB Recommended application area tecnalia Inspiring Business Bifacial with dual glass 1. Most on-ground PV station; 2. High labor cost area, like EU, Japan, Australia (can effective receive labor cost); 3. Commercial roof-top 1. Most on-ground PV station; 2. In floating projects as well as super high wind speed area, bifacial with dual glass is a better choice project Innovation in bifacial technology for P and N-type modules to help boost efficiency and power density. Roman Giehl, Jinko Solar. BiFi July 2020. GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#23go PV Current status Fixed installations vs 1-axis tracking First bifacial installations were fixed. • However Single-axis tracking (aka HSAT - Horizontal Single Axis Traking) is a cost-effective deployment strategy for large-scale ground-mount photovoltaic systems in regions with high direct-normal irradiance. • Bifacial modules in 1-axis-tracking systems boost energy yield by 4%-15% depending on module type and ground albedo, with a global average of 9%. This benefit is in addition to the 15%-25% energy gain already afforded by single-axis tracking relative to fixed-tilt deployments. Currently, lower LCOE values are being obtained with bifacial+HSAT (< 0.02 $/kWh) Energy Gain (%) Simulated, albedo 0.35 Location: Haining, China 25% Monofacial Fixed + 10-25% Monofacial Tracking Bifacial 20% +4-15% Tracking 15% 10% Pelaez et al. Model and Validation of Single-axis tracking with bifacial PV. IEEE Journal of Photovoltaics, vol. 9, no.3, May 2019. Innovation in bifacial technology for P and N-type modules to help boost efficiency and power density. Roman Giehl, Jinko Solar. BiFi July 2020. 5% Benchmark 0% 9,6% 10,4% Monofacial-fix Monofacial-tracker Bifacial-fix tecnalia 22,6% Bifacial-tracker Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#24go PV Current status Trackers: 1P vs 2P • • Most common tracker geometries: 1 module in portrait or 2 modules in portrait (1-P or 2-P) Currently it is not clear which is the best option: trackers manufacturers are providing their studies Topics under discussion: . Bifacial Gain . Operating temperature of modules . Flexibility in design • Possible backside shadowing in 1-P due to torque-tube • Operation and Maintenance (O&M) differences 1-P 2-P (a) RADIANCE image showing torque tube behind a module's row and (b) (b) Grear across the module averaged over a sunny day when torque tube is present, compared to Grear for the module without torque tube (tubeless). Pelaez et al. Model and Validation of Single Axis Tracking with Bifacial PV. IEEE Journal of Photovoltaics, vol. 9, no. 3, May 2019. Grear X 100/Grear,tubeless-100 [%] tecnalia (a) Torque tube shading loss -10- -15 30cm gap 20cm gap 10cm gap T T T -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 Module X position [m] (b) Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#25Current status go PV Cooling: Tracker Topology VV (h) √√ch) Fast/cool Medium Slow/hot Fast/cool 16 ft 33 ft Medium Slow/hot イ イ Average GCR 40% Pitch AT AEnergy Temp. 1P Tracker 2P Tracker 5 m 10 m 33.96°C 3.52°C 1.3% 30.44°C 30.3°C 34.3°C 36.3°C Temperature 30 Height 1-in-P 2-in-P Average Module Temperatures in Uc Function 25 15 Uc W/m'k Higher module and pitch promotes better cooling. Cooling reduces module temperature and increases energy yield. The information contained in this presentation may be subject to confidentiality BITEC Field Data 1P vs 2P - 1P Standard Measured 2P SF7 Tracker Bifacial Gain Bifacial 16.8% Fall 2018 19.2% 12,6% Winter 2019 14,3% 10,4% Spring 2019 1.35m 12.1% 13,7% Summer 2019 15,8% Yield + 2.1% 16,6% Fall 2019 19,5% 16,8% Winter 2020 13.6% 15.7% 12.5% Spring 2020 18,7% 14,5% GCR 0.4 Albedo = 55.6% 2.35m Test Considerations: 8 Soltec Results based on energy performance at module level Only internal Trackers considered (avoid effect of higher diffuse on external Trackers) Only central modules considered (avoid effect of higher diffuse on edge modules) Results expected to be the average for large utility scale plants ⚫ Geotextile AEM With bigger spaces between Trackers easies the access for cleaning and trimming the grass. Higher Trackers allow bigger machinery to reach the whole surface underneath Effective height useful for bifacial reflection depends on the gras level, so relative height does. Down 2.2m 2.35m Down 0,5m 1P trackers 2P Soltec trackers influence of useful tracker height in relation to vegetation growth 1P vs. 2P. Source: Solter 4.1m Up Relative height (p.u.) 0.80 0.60 0,50 0,40 0.30 0 20 Grass height (cm) 1P-50cm 10-30cm 2P-50cm 60 The information contained in this presentation may be subject to confidentiality obligatione arising frum Softec's contractual relationships with third parties NX Horizon (1P) vs NX Gemini (2P): Beyond BF Gain 9 Soltec Bifacial Gain is not the only Metric. System-level design affects total energy yield For a constrained site with irregular boundaries: nextracker COMPON NX Horizon 37% GCR Bifacial PV Tracking: The Simulation and Optimization of Yield Gain. Soltec webinar. Apr 2018 Optimizing Plant Performance with Smart Solar Trackers & Bifacial Technology. Melissa Cooke, Nextracker. BiFi July 2020. NX Gemini 35% GCR +~0.5% yield 2020 NEXTRACKER Proprietory & Confidential 20 tecnalia Inspiring Business Early Findings: NX Horizon (1P) vs NX Gemini (2P) Near Identical Monofacial Performance, 1.3-2.4% Higher Bifacial Gain on NX Horizon (1P) NX Horizon (1P) 31% GCR 1.5m Axis Height NX Gemini (2P) 31% GCR 2.05m Axis Height High Albedo 1st half March 2020 Low Albedo 2nd half March 2020 11.4 96 519 Bifacial Whitepaper with modeled vs. measured analysis to be released Q3 2020 nextracker Company 9.0 % 3.8 % one Contidense bood GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#26go PV Current status Vertical configuration of bifacial Bifacial modules open a new configuration: vertical modules facing East-West • Normally PV production is lower than optimal configuration • But the production profile might be interesting: . Peak production during the morning and in the afternoon • Depending on hourly energy prices, this profile production may worth • New applications also for in Agrivoltaic (Agri-PV) Towards large-scale deployment of bifacial photovoltaics. Nature energy vol 3 443-446, June 2018 a Slanted S/N b Horizontal B/T Direct sunlight سي) Direct sunlight Output power (W ---------- c Vertical E/W Direct sunlight tecnalia Inspiring Business Direct sunlight Reflected sunlight Reflected sunlight Reflected sunlight Reflected sunlight Up to 30% 4 6 8 10 12 14 16 18 20 Time of day - S/N bifacial -- S/N monofacial B/T bifacial -B/T monofacial E/W bifacial --EW monofacial GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#27go PV Current status Bankability The uncertainty of PV production of bifacial systems means more investment risk. • More investment risk implies higher interest rates. • Weighted Average Capital Cost (WACC) is related to the interest rate and is crucial for PV projects development. • The more bifacial installations, projects and studies there are, the less bifacial production uncertainty. • Simulation tools are a key part of the bifacial technology deployment. 140 130 120 110 100 ㅁ The LCOE calculations for a monofacial PV system, in dependence on the specific yield LCOE [euro/MWh] 90 80 70 60 50 40 (kWh/m2) for a WACC ranging 30 from 4% (e.g. best cases in 20 Germany) to 12% (e.g. worst 10 cases in Greece) 0 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 Yearly energy yield [kWh/kWp] Bifacial Photovoltaics: Technology, applications and economics. 2018 WACC: 12% ーロー 10% 8% 6% ■-4% 55 LCOE [euro/MWh] 40 55 45 Results of LCOE calculations as in (a) but for a location featuring 1,750 kWh/kWp for monofacial systems (e.g. south of Spain). 35 30 30 0 5 10 (b) tecnalia Bifi price premium: 20% -0-15% 10% 5% 0% Inspiring Business 15 20 25 30 35 40 45 50 Bifacial gain [%] JRSES TECHNICAL FOCUS ON FUTURE SOLAR PV'SYSTEMS October 26-29th 2020#28дору go PV Conclusions tecnalia . • Bifacial is a mature technology already in the market with reliable products. However there are still opportunities to improve different key aspects in the cell, modules and system level. The lowest LCOE nowadays are with bifacial modules + 1-axis tracking systems. The market share of bifacial modules is expected to increase significantly in the following years. New parameters should be understood and considered for bifacial systems design. Every utility PV project should, at least, evaluate the bifacial PV option. Bifacial Ratio (i.e. irradiation at backside) is difficult to foreseen. Specific software tools have been developed. Interest rates are directly related with bifacial performance uncertainty. It is decreasing due to several published studies focused on software validation and real measurements. Inspiring Business GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#29go PV FROM RESEARCH TO cea tech GLOBAL OPTIMIZATION OF INTEGRATED PHOTOVOLTAIC SYSTEM FOR LOW ELECTRICITY COST This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 792059 Thank you for your attention! [email protected] [email protected] Follow us + in enel Green Power ines INSTITUT NATIONAL DE L'ENERGIE SOLAIRE REFU Elektronik EPFL RSE Ricerca Sistema Energetico GXC Coatings Transparent Performance LEITET Technological Center MONDRAGON MASSEMBLY tecnalia Inspiring Business CONVERT valmont c#30tecnalia Inspiring Business go PV PV Modules: Bifacial technology 7.1.1 Index of the session . 14:30 - Introduction to bifacial technology [D. Valencia - TECNALIA] • 14:50 - Current status of bifacial technology [D.Valencia - TECNALIA] • • 15:05 - Bifacial modules developed in GOPV project: beyond the market status [Paul Berthelemy - CEA] 15:40 - 15 min BREAK 15:55 - Bifacial PV production software options [D.Valencia - TECNALIA] 16:05 - Bifacial PV production: practical case [D.Valencia - TECNALIA] GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#31tecnalia Inspiring Business go PV PV Modules: Bifacial technology 7.1.1 Index of the session . 14:30 - Introduction to bifacial technology [D. Valencia - TECNALIA] • 14:50 Current status of bifacial technology [D.Valencia - TECNALIA] • • 15:05 - Bifacial modules developed in GOPV project: beyond the market status [Paul Berthelemy - CEA] 15:40 15 min BREAK 15:55 - Bifacial PV production software options [D.Valencia - TECNALIA] 16:05 - Bifacial PV production: practical case [D.Valencia - TECNALIA] GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020#32go PV Bifacial PV production Model approaches . Objective: calculate the radiation received at the module backside (i.e. Bifacial Ratio) Bifacial Ratio State-of-the-Art: View factor models vs Ray tracing models VIEW FACTOR RAY TRACING rtr rtr n- 052 Ost k = Gback Gfront tecnalia Inspiring Business 2D model. Geometrical/analytical description No differences between modules in the middle and on the edge of a row No details can be included like trackers torque-tube or transparency between cells Fast computation 3D model. The reflections of a set of rays are calculated More detailed analysis, with differences between all the modules and cells Slow/ Very slow computation (depending on detail and PV installation size) Not available in most common commercial SWs . Available in commercial software (e.g. PVSyst and SAM) GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS 32 October 26-29th 2020#33go PV Bifacial PV production Simulation tools - View Factor View factor-Already implemented in commercial software PVSyst PVSYST SAM 2018813 File Add untitled Photovoltaic Residential LC SAM - NREL in System Design SunPower SPR-X20-445-COM Shading and Layout Losses SunPower SPR-X21-255 SunPower SPR-X21-335 SunPower SPR-X21-335-BLK Lifetime Modide Characteristics at Reference Conditions Battery Storage System Costs Financial Parameters Incentives Electricity Rates Electric Load Vmp rel Ac Na Lxcre V_c_ref ecifications 573 1.631 96 6.09 57.6 -0.3 dule Database 573 1.631 9 6.09 675 -03 573 1.651 46 6.09 576 -403 573 1.631 96 6.09 676 -0.3 58 767 2.162 128 6.21 905 -03 5.95 428 1,182 72 6.3 51 43 573 1.631 16 57.9 -43 5.95 573 1.671 96 679 -0.3 Refence conditione Total imadiance-1000 W/ml, Cell temp-25C SunPower SPR-X21-335-BLK 60 Module Voltage (Volts) Nominal efficiency 20.5321 % Temperature coefficients Maximum power (Prop) 335.205 W -0.310°C -1035 wes Max power voltage (Vimp) 57. Vdc Max power current (Imp) 58 Adc Open circuit voltage (Vac) 67.9 Vdo 0250%C Ade -0.1.70 V/°C AUT Short circat curent (he Bifacial Specifications Muskules are bilacial Transmission Fraction Ground clearance height Bifaciality am 1 • Examples of software using view factor: PVSysts, SAM, bifacialvf, MOBIDIG, pvfactors, ... . Commercial software with an easy interface tecnalia Inspiring Business • . • • There might be doubts regarding the value of some inputs like shading loss factor or backside mismatch loss factor. This input values are being studied with ray-tracing tools. According to recent studies, current VF software (SAM, PVSyst) appears to be conservative relative to measured rear irradiance¹. However, other studies shows that 2D VF models are enough accurate 2,3 Probably they are the mostly used due to its "historical reliability" and because they are widely used and known in the sector. [1] Ultimate Bifacial Showdown: 75kW Field Results. Silvana Ayala Peláez, NREL. BiFi July 2020. [2] Field Testing Meets Modeling: Validated Data on Bifacial Solar Performance. Kyumin Lee, Array Technologies. BiFi July 2020. [3] Amir Asgharzadeh et al. A Benchmark and Validation of Bifacial PV Irradiance Models. GoPV Project | 1st TRAINING COURSES TECHNICAL FOCUS ON FUTURE SOLAR PV SYSTEMS October 26-29th 2020