Bifacial PV System Performance - NREL

1 Bifacial PV System Performance : Separating Fact from Fiction Chris Deline, Silvana Ayala Pel ez, Bill Marion, Bill Sekulic, Michael Woodhouse, and Josh Stein (Sandia National Labs). PVSC-46, Chicago, IL 2019. nrel /PR-5K00-74090. Bifacial PV in the news nrel | 2. Status of Bifacial Installations 2019. nrel | 3. R. Kopecek, Photonics North 2019, May 22nd Quebec Historic & projected PV market Different cell technology Bifacial cell in world market SHJ. PERC. Al-BSF. ITRPV 2018, PV Celltech Conference March 10-11th 2019 Penang Malaysia nrel | 4. PERC cell technology easily Bifacial Reduced screen-print metallization . Module bifaciality = =. (p-PERC) (n-PERT) (Si Heterojunction). Thorsten Dullweber et al. PERC+: industrial PERC solar cells with rear Al grid enabling bifaciality and reduced Al paste consumption, Prog.

2 Photovolt: Res. Appl. (2015) nrel || 5. Monofacial vs Bifacial module manuf. cost Monofacial PERC PERC+ n-PERT SHJ Bifacial Calculated Minimum Sustainable Price R&D, Sales, Administrative Module Assembly BOM Materials Stringing and tabbing consumables Other Cell direct costs Cell Metallization April 2019 Wafer pricing Additional details given in: (1) M Woodhouse, B Smith, A Ramdas, and R Margolis Economic Factors of Production Affecting Current and Future Crystalline Silicon Photovoltaic Module Manufacturing Costs and Sustainable Pricing , In preparation. (2) A Faes, C Ballif, M Despeisse, et al, Metallization and interconnection for high efficiency Bifacial silicon heterojunction solar cells and modules , Photovoltaics International, 3, 1 12 (2018) (3) A Louwen, W van Sark, R Schropp, and A Faaij, A Cost Roadmap for silicon heterojunction solar cells , Solar Energy Materials and Solar Cells, 147, 295 314 (2016) nrel | 6.

3 Bifacial Performance Modeling Photo credit: Prism Solar Bifacial total irradiance = + ) ( ) ( . Gfront Grear * _ . 0 . Module bifaciality _ = nrel | 8. 0 . Modeling Rear Irradiance Grear = Gdiffuse,r + Greflected,r + Gbeam,r nrel | 9. Modeling Rear Irradiance Grear = Gdiffuse,r + Greflected,r + Gbeam,r nrel | 10. What Bifacial gain can be expected? Bifacial energy gain BGE. = / 1. = ?? nrel | 11. Surface Albedo has a big effect Rear irradiance, single module at STC. (1kWm-2 frontside). 500. White EPDM. 400. Grear Wm-2. Built-up roof 300. 200. Soil Concrete 100. Asphalt 0. 0 1. Ground reflectance (R). NASA Earth Observations, R. Kopecek and J. Libal, Bifacial Photovoltaics: Technology, applications and economics, IET publishing, 2019 nrel | 12. System GRear experiences self-shading 150. 120. Single row Grear (Wm-2).

4 90 Front row 60 Interior row Grear: -50%. 30. 0. 0 5 10 15 20. Modules per row nrel | 13. C. Deline et al., Assessment of Bifacial Photovoltaic Module Power Rating Methodologies Inside and Out, J. Photovoltaics 7, 2017. Photo credit: Bifacial Performance Models Bifacial_Radiance Model for Rear Irradiance Complicated geometries possible, including racking and terrain. radiance uses backward ray-trace to evaluate the irradiance (W/m2) at the modules Open-source software freely available at nrel | 15. Bifacial_Radiance Model for Rear Irradiance Measured 300 View Factor radiance 250. h = Grear [Wm-2]. 200. 150. 100. h = 50. 0. 50 150 250 350 450 550. Back Sensor Position (mm). Open-source software freely available at Field validation shows good agreement with close-mount rooftop mockup S. Ayala Pelaez, C. Deline, S.

5 MacAlpine, B. Marion, J. Stein, R. Kostuk, "Comparison of Bifacial solar irradiance model predictions with field validation" IEEE Journal of Photovoltaics, 2019, vol 9 no. 1, pp. 82-88. View Factor Model for Rear Irradiance PVSyst Simple Fast Common basic computationally Behind geometry inexpensive SAM, Pvsyst, and others nrel | 17. View Factor Model for Rear Irradiance Grear is summed over 180 field-of-view: 180 . Grear = , + ;. =1 . 1. = cos 1 cos ;. 2. = ( ). = , , ;. Irradiance sources: sky, ground (shaded or unshaded). B. Marion et al., A Practical Irradiance Model for Bifacial PV Modules, 2017. B. Marion, Numerical method for angle-of-incidence correction factors for diffuse radiation incident photovoltaic modules, 2017 nrel | 18. nrel SAM Model 14 1-axis tracking model comparison 13. 12. GRear \ GFront [%].

6 Bifacial_Radiance 11. 10 PVSyst 9 SAM. albedo 8. Ground Coverage Ratio SAM N. DiOrio, C. Deline, Bifacial simulation in SAM , presented at 5th BifiPV in Denver, CO 2018. S. Ayala Pelaez, C. Deline, S. MacAlpine, B. Marion, J. Stein, R. Kostuk, "Comparison of Bifacial solar irradiance model predictions with field validation". IEEE Journal of Photovoltaics, 2019, vol 9 no. 1, pp. 82-88. nrel | 19. Bifacial trackers, 75 kW. 5 Bifacial technologies Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance nrel | 21. Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance nrel | 22.

7 Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance nrel | 23. Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance nrel | 24. Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance nrel | 25. Bifacial System configuration 20 modules ( kW) / row 4 PERC, 1 SHJ Bifacial strings 3 PERC monofacial strings Module electronics / monitoring String kWhDC monitoring Front, rear POA irradiance = Front POA.

8 = Rear POA nrel | 26. Initial field results Bifacial trackers . BGE = 1.. Bifacial Bifacial gain: 15% gain: 5%. nrel | 27. Initial field results Bifacial trackers . BGE = 1.. Bifacial Bifacial gain: 15% gain: 5%. nrel | 28. Initial field results Bifacial trackers . BGE = 1. More diffuse = . higher BGE. nrel | 29. Initial field results Bifacial trackers . Annual power BGE = 1.. histogram 50% energy production nrel | 30. Modeled vs Measured kWDC Power Monofacial Bifacial *SAM using 15-minute measured DNI, DHI, albedo from SRRL BMS. Andreas, A.; Stoffel, T.; (1981). nrel Solar Radiation Research Laboratory (SRRL): Baseline Measurement System (BMS); Golden, Colorado (Data); nrel Report No. DA-5500-56488. Bifacial systems assume 5% shading loss, 5% mismatch loss, 0% transmission factor nrel | 31. Bifacial modeling sensitivity BGE =.

9 1.. 11%. PERC Bifacial gain 4-8% 9%. 3 sensitivity Ground PERC Si-HJT. cases: albedo Bifi Bifi 8%. Field test High case results to date Average case 6%. Low case Si-HJT Bifacial gain 4%. *SAM using 15-minute measured DNI, DHI, albedo from SRRL BMS. Andreas, A.; Stoffel, T.; (1981). nrel Solar Radiation Research Laboratory (SRRL): Baseline Measurement System (BMS); Golden, Colorado (Data); nrel Report No. DA-5500-56488. Bifacial systems assume 5% shading loss, 5% mismatch loss, 0% transmission factor nrel | 32. Market Analysis LCOE Analysis for Monofacial and Bifacial PV Systems Bifacial vs Monofacial LCOE at various US sites 6% Nominal Discount Rate. Single Owner and Unlevered Pro Forma with 30% ITC. $45 Monofacial LCOE Bifacial LCOE. Seattle, WA $ $ LCOE (2019 USD/MWh). $40. Kansas City, MO. $35. $30 Miami, FL.

10 Daggett, CA. $25. 1,200 1,450 1,700 1,950 2,200 2,450. Site kWh/kW annual Pre-Tariff situation illustration based on R. Fu, D. Feldman, R. Margolis, M. Woodhouse, K. Ardani, Solar Photovoltaic System Cost Benchmark: Q1 2017 . nrel /TP-6A20-68925, 2017 And Solar Energy Industries Association. US Solar Market Insight: 2018 Year in Review. Washington, DC March. 2019. nrel | 34. Assumptions: 100MW System , DC-AC ratio, GCR. LCOE Analysis for Monofacial and Bifacial PV Systems Bifacial vs Monofacial LCOE at various US sites PRE-TARIFF Situation LCOE - Miami, FL. 6% Nominal Discount Rate. Single Owner and Unlevered Pro Forma with 30% ITC. $ Bifacial PERC. Monofacial LCOE Bifacial LCOE $ Low case $ $45. LCOE (2019 USD/MWh). Seattle, WA $ $ +4% BGE. LCOE (2019 USD/MWh). +1 /w $ Bifacial $40. Avg. case $ +6% BGE.