Key findings from Singapore Floating PV Testbed Project ZHAO Lu, LIU Haohui, Jason LUN LEUNG, Vijay KRISHNAMURTHY, Thomas REINDL Solar Energy Research Institute of Singapore (SERIS) International Floating Solar Symposium (IFSS) 24-26 Oct, 2017 1 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Outline q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion 2 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Floating PV Testbed (2) q Project Site Plan Floating PV Systems SolarGy / NRG Energia SolarGy / 4C Solar Phoenix Solar / C&T Sunseap / C&T Sunseap / C&T BBR Greentech / Solaris Rooftop Upsolar / Koiné Multimedia Reference Floating Pontoon System REC / Takiron Reservoir Sharp / SMCC Million Lighting/ATS / HDB 4 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Floating PV Testbed (3) q Supporting Infrastructure Works Substation / Inverter room Launch ramp Floating pontoon 5 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Floating PV Testbed (4) q Large scale FPV testbed q Side-by-side comparison of major commercial FPV technologies q Detailed monitoring Ø Environment Ø Energy yield Ø Module temperature Ø Bi-facial module Ø Active cooling q Economics, LCOE 6 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Floating PV Testbed (5) q Floating platform technologies in the testbed 7 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Floating PV Testbed (6) q Comprehensive monitoring infrastructure, with >500 parameters Ø Meteorological station (reservoir & rooftop) Ø PV System performance monitoring DC (PV String) AC (PV array) Motion sensor Module Temp. 8 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Outline q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion 9 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed operating conditions (1) q Ambient temperatures q Humidity Ø T Ø ambient on water (vs. rooftop) Humidity on water is is consistently lower generally higher 10 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed operating conditions (1) q Wind Speed q Wind Direction Ø Wind speed on water (vs. Ø Less obstruction on water rooftop) is generally higher 11 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed operating conditions (2) q Albedo Ø Albedo of water surface is rather small, 5~6% measured Albedo for 15 Mar 2017 Daily average 12 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed operating conditions (2) q Albedo Ø Water surface reflectivity is usually less than 10% at high incident angles (around 3 ~ 6% according to most reported measurements). source: wikipedia Reflectivity of smooth water at 20 °C (refractive index=1.333) 13 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Comparison of operating conditions (3) On-shore and off-shore module temperatures q Module temperatures depend on floating structures as well as location within the floats. q FPV modules have cooler operating temperatures (by ~5 ̊ C). Float structure B Float structure A Daily weighted average module temperatures 14 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Cooling effect on PV module Temp Free Standing Minimized Footprint on water Very Good convective cooling Small Footprint on water Good convective cooling Large Footprint on water Water surface partially blocked 15 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Module cooling q Cooling effect (indicated by heat loss coefficient) is dependent on floating structure. Thermal loss factors ( U in W/m ² ·k) 𝑉 " 𝑈 $%&& − 𝑈 ()* = 𝐵𝑚𝑞ℎ𝑏 " 𝐻 23$ " (1 − 𝐹𝑔𝑔) 𝑉 = 𝑉 $ + 𝑉 : " 𝑤 v = wind speed in [m/s] Well-ventilated system Insulated system Compact, dual-pitch design 16 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed system performance (1) q FPV system performance ratio (from Apr till Sep 2017) Ø Up to about 15% higher than typical rooftop PV systems in Singapore (with PR of 75 ~ 80%) Very good ventilation (slightly overestimated due to reduced module tilt) Severe soiling due to bird droppings Frequent inverter fault, significant downtime * Typical rooftop system PR in Singapore Note: This reference system is much better than typical rooftop systems in Singapore. • Good ventilation • Bi-facial modules * PR values are corrected for DC cabling loss System numbering is reordered for anonymity 17 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Testbed system performance (2) q Bifacial modules Ø On rooftop, bi-facial string outperforms mono-facial strings Ø On water, bi-facial string does not seem to outperform mono- facial strings, due to low albedo on water Ø However, bi-facial might have benefit in the long term (dual glass, slower moisture ingress) Bifacial string vs. mono-facial strings Daily PR (DC side) 18 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
Outline q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion 19 SERIS is a research institute at the National University of Singapore (NUS). SERIS is sponsored by the National University of Singapore (NUS) and Singapore’s National Research Foundation (NRF) through the Singapore Economic Development Board (EDB).
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