Assessing PV Potential on New York City s Network Distribution System

Transcription

1 Assessing PV Potential on New York City s Network Distribution System Kate Anderson National Renewable Energy Laboratory May 19, 2010 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC

2 Background Background New York City goal: 600 MW of renewable electricity by 2030 City uses a secondary network distribution system: each customer receives power through several parallel feeders and transformers Network protectors open if power reverses Ensures power does not backfeed from one transformer through another Utility concern: Distributed PV systems may disrupt network protection and reduce network reliability 2 2

3 New York City Distribution System Generating Station (electricity generated at 13.8 to 22.0 kv) Transmission Substation Area Substation (voltage stepped down to distribution voltage) Transformers (voltage stepped down to 480, 208, or 120 V) 62 Network Systems Supply 86% of System Demand Overhead System Supplies 14% of System Demand Graphic courtesy of Con Ed 3

4 Objectives Objectives Assess potential electricity generation of rooftop photovoltaics in two utility networks Compare PV generation to network loads Analyze exporting energy trends & assess network impact 4 4

5 Approach Objectives Approach Analyze 2 utility networks: Herald: High density high-rise buildings Bay Ridge: High density low-rise buildings 5

6 Methodology Methodology Objectives 1. Calculate total roofspace 2. Estimate space suitable for PV 3. Calculate potential PV capacity 4. Calculate hourly energy production 5. Estimate shading losses 6. Compare PV generation to network loads 6 6

7 1. Calculate Total Rooftop Space Methodology 1. Calculate Objectives Total Roofspace NREL s In My Backyard (IMBY) software 7 7

8 2. Estimate Suitable Space Methodology Calculate Estimate Objectives Total Suitable Roofspace Space Calculate reductions for: Occupied Space Shading from Rooftop Obstructions Space for Access and Safety Roof Orientation Structural Adequacy Historical Building Codes 8 8

9 3. Calculate Total Capacity Methodology Calculate Objectives Total Roofspace Capacity Herald (High-Rise) Bay Ridge (Low-Rise) Total Rooftop Area (m 2 ) 147,000 4,459,000 Percent Suitable Space 12% 40% Total Suitable Rooftop Space (m 2 ) 17,640 1,819,600 Total Rooftop PV Capacity (MW DC)* *100 W DC/m 2 9 9

10 4. Calculate Energy Production Methodology Calculate Objectives Energy Total Roofspace Production Use 2005 Perez satellite solar resource data and PVWatts model to estimate production Hourly AC energy production based on: PV DC rating PV azimuth and angle (assume horizontal mounting) Incident solar radiation PV cell temperature Reflection losses DC to AC derate factor 10 10

11 5. Apply Shading Losses Methodology Calculate Apply Objectives Shading Total Roofspace Losses Model typical areas in each network Calculate hourly shading factors Reduce PV generation South West Zenith East 11 11

12 Hourly Shading Losses Results 1. Calculate Hourly Objectives Shading Total Roofspace Losses Herald Network (High-Rise) Bay Ridge Network (Low-Rise) 12

13 6. Compare PV Generation to Network Compare PV Generation to Network Loads Results 1. Calculate Objectives Total Roofspace Loads Maximum % of load: 3.58% Herald Network (High-Rise) 80 MW Jan-05 Apr-05 Jun-05 Sep-05 Dec-05 Load PV Generation 13

14 Compare PV Generation to Network Loads (continued) Results Maximum % of load: 136% Bay Ridge Network (Low-Rise) 150 MW Jan-05 Feb-05 Apr-05 May-05 Jul-05 Sep-05 Oct-05 Dec-05 Load PV Generation 14 14

15 Compare 6. Bay Compare PV to Network Loads 1. Ridge Calculate Energy PV Objectives Generation Total (continued) Exported Roofspace to by Network Loads Month Energy Exporting Trends: Monthly Results MWH January February March April May June July August September October November December 15 15

16 Compare 6. Bay Compare PV to Network Loads 1. Ridge Calculate Energy PV Objectives Generation Total Exported Roofspace to by Network by Month Day (continued) Loads Energy Exporting Trends: Daily Results MWH

17 Compare 6. Bay Compare PV to Network Loads 1. Ridge Calculate Energy PV Objectives Generation Total Exported Roofspace to by Network by Month Time (continued) Loads Energy Exporting Trends: Hourly Results MWH :00 10:00 11:00 12:00 13:00 14:00 15:00 17

18 Conclusions PV unlikely to export in areas of dense high-rise buildings Limited roofspace, high shading losses, high loads PV generation can exceed loads in areas of dense low-rise buildings Need to monitor installations more carefully Exporting most likely to occur during Spring weekends at mid-day Future research should study exporting at individual building level 18 18