Key findings from Singapore Floating PV Testbed Project ZHAO Lu, - - PowerPoint PPT Presentation

key findings from singapore floating pv testbed project
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Key findings from Singapore Floating PV Testbed Project ZHAO Lu, - - PowerPoint PPT Presentation

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


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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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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

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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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Outline

q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion

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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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Floating PV Testbed (2)

q Project Site Plan

Floating Pontoon Rooftop Reference System

Reservoir

Million Lighting/ATS / HDB SolarGy / NRG Energia SolarGy / 4C Solar Phoenix Solar / C&T Sunseap / C&T Sunseap / C&T BBR Greentech / Solaris Upsolar / Koiné Multimedia REC / Takiron Sharp / SMCC

Floating PV Systems

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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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Floating PV Testbed (3)

q Supporting Infrastructure Works

Floating pontoon Substation / Inverter room Launch ramp

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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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Floating PV Testbed (4)

q Large scale FPV testbed q Side-by-side comparison

  • f 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

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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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Floating PV Testbed (5)

q Floating platform technologies in the testbed

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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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Floating PV Testbed (6)

q Comprehensive monitoring infrastructure, with >500 parameters Ø Meteorological station (reservoir & rooftop) Ø PV System performance monitoring

Motion sensor Module Temp. AC (PV array) DC (PV String)

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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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Outline

q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion

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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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q Ambient temperatures

Ø T

ambient on water (vs. rooftop)

is consistently lower

Testbed operating conditions (1)

q Humidity

Ø Humidity on water is generally higher

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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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Testbed operating conditions (1)

q Wind Speed

Ø Wind speed on water (vs. rooftop) is generally higher

q Wind Direction

Ø Less obstruction on water

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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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Albedo for 15 Mar 2017 Daily average

Testbed operating conditions (2)

q Albedo

Ø Albedo of water surface is rather small, 5~6% measured

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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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Reflectivity of smooth water at 20 °C (refractive index=1.333)

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

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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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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 A Float structure B

Daily weighted average module temperatures

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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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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

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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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Module cooling

Well-ventilated system Insulated system

q Cooling effect (indicated by heat loss coefficient) is dependent on floating structure.

Thermal loss factors (U in W/m²·k)

𝑉 " 𝑈$%&& − 𝑈()* = 𝐵𝑚𝑞ℎ𝑏 " 𝐻23$ " (1 − 𝐹𝑔𝑔) 𝑉 = 𝑉$ + 𝑉: " 𝑤

v = wind speed in [m/s]

Compact, dual-pitch design

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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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Note: This reference system is much better than typical rooftop systems in Singapore.

  • Good ventilation
  • Bi-facial modules

Severe soiling due to bird droppings Very good ventilation (slightly overestimated due to reduced module tilt)

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%)

Typical rooftop system PR in Singapore Frequent inverter fault, significant downtime

System numbering is reordered for anonymity * PR values are corrected for DC cabling loss

*

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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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Bifacial string vs. mono-facial strings

Daily PR (DC side)

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)

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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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Outline

q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion

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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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Issues encountered (1)

Soiling – from bird droppings q Bird droppings observed on floating PV modules Ø Partial shading Ø Reduced performance, less energy yield Ø Cell reserve biased, hot spots, => can lead to accelerated module degradation q Possible solutions Ø Part of the O&M routine (i.e. immediate actions / cleaning) Ø Barrier methods Ø Non-barrier methods § Ultrasonic, Sonic Repeller § Visual Scare Device

Singapore floating PV Testbed Queen Elizabeth II reservoir, UK

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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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Issues encountered (2)

Constant movement of floating platform q Mechanical stress Ø At the joints of rigid structures Ø On equipotential bonding tape/wire Ø At the earthing tape connection for grounding

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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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Issues encountered (3)

Insulation faults q Insulation test failure for inverters Ø The insulation resistance (Riso) dropped over time for floating PV strings Ø Inverters measure Riso. When Riso does not meet the preset threshold inverters do not start. Ø Common result: inverters start late (till the Riso limit is passed).

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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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Other potential issues

Due to proximity to water, high humidity

q Potential Induced Degradation (PID) Ø Anti-PID modules preferred q Corrosions (more aggravated for off-shore environments) Ø Combiner boxes Ø Inverters Ø Metal supporting structures q Risk of solar cables submerged in water Ø Electrical safety, earth leakage Ø Performance drop, system downtime q Structural Ø Anchoring / mooring needs to be carefully assessed during feasibility study

Þ Highly valuable results from this testbed will potentially lead to new technical standards for Floating PV (via IEC TC 82)

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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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Outline

q Introduction to the Floating PV Testbed in Singapore q Operation conditions and system performance analysis q Field experience: issues encountered q Conclusion

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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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Conclusion

q Floating PV market is taking off: Ø Large potential globally, with enormous opportunities in Asia: China, Japan, Taiwan, India, Pakistan, Sri Lanka, ASEAN Ø Hybrid operation of Hydropower and Floating PV has numerous advantages and huge deployment potential q FPV system performance in the Singapore testbed Ø FPV PR ranges 79% ~ 93% Up to 15% higher than typical rooftop system in Singapore Ø FPV modules generally cooler. Cooling effect of FPV modules depends on floating structures and weather conditions Ø Bifacial modules does not seem to outperform mono-facial modules on water Ø Initial technical issues identified, but no major obstacle