Grid Tied PV Systems – Part 5 Session 16 Grid Tied PV Systems – Part 5 Balance of Systems Three-Phase Systems October 22, 2015

Session 16 content Grid-Connected PV Systems Wrap-up of Residential PV System Example Design Considerations for Large Scale Systems

Learning Outcomes An examination of the impact of size (scale) on photovoltaic system design

Learning Outcomes An examination of the importance of the Balance of System components

Grid-Tied PV Systems – The Design Process Design Steps in any Residential Scale System Examination of site and estimation of performance Securing financing Carrying out PV system engineering and design Securing relevant permits Construction Inspection Connection to the grid Performance monitoring

Grid-Tied PV Systems – The Design Process Steps in annual system performance design Evaluation of solar availability and electrical consumption PV array sizing Inverter selection Module selection Balance of system

Grid-Tied PV Systems – PV system engineering and design Step 5: Balance of System (BOS) component selection Module extension wires Junction box and/or Combiner box Wire and Conduit to connect JB or CB to inverter DC and AC disconnects at inverter Wire and Conduit from inverter to Point of Utility Connection (PUC)

Grid-Tied PV Systems – PV system engineering and design Block diagram of two source circuit PV system

Grid-Tied PV Systems – PV system engineering and design AC disconnect between PV modules and service panel

Grid-Tied PV Systems – PV system engineering and design AC disconnect between PV modules and service panel

Grid-Tied PV Systems – PV system engineering and design Second AC disconnect between PV modules and service panel

Grid-Tied PV Systems – PV system engineering and design Wiring of service panel

Grid-Tied PV Systems – PV system engineering and design Service panel, PUC

Grid-Tied PV Systems – PV system engineering and design Service panel, PUC

Grid-Tied PV Systems – PV system engineering and design Service panel, PUC

Grid-Tied PV Systems – PV system engineering and design

Grid-Tied PV Systems – PV system engineering and design

Grid-Tied PV Systems – PV system engineering and design PV wiring THHN – Thermoplastic, High Heat, Nylon Coated – 90C THWN – Thermoplastic, High Heat, Water resistant, Nylon Coated – 75C USE-2 – Underground Service Entrance PV – https://www.youtube.com/watch?v=dDbaJQBdpbc

Grid-Tied PV Systems – PV system engineering and design Voltage drop and wire sizing NEC requirement: Total voltage drop in feeder and branch circuits less than 5% (combined) or 3% (either) Size 18 (s) 10 (s) 4 (str) 0 (str) Rdc (W/kft) 7.77 1.21 0.31 0.12 Imax (A) 14 40 95 170

Grid-Tied PV Systems – PV system engineering and design Branch circuits are source circuits that connect PV arrays to power conditioning Feeder circuits are PV inverter output circuits that connect to the utility (service panel) Rule of thumb: Don’t allow voltage drops to exceed 2% in any circuit

Grid-Tied PV Systems – PV system engineering and design Ampacity and wire sizing NEC requirement (690.8): Ampacity > (1.25) * (1.25) * ISC = 1.56 ISC Temperature derating from Tambient > 300C (NEC 310.15) 3 hrs of max current flow Focusing effects of clouds T (0C) 26-30 31-35 41-45 Correction 1.00 0.96 0.82

Grid-Tied PV Systems – PV system engineering and design M&V Example (modified) ISC = 8.05A -> 1.56 ISC = 12.6A Case 1: Wire size 10 AWG 300C ampacity -> 40A Suppose the ambient temperature will rise to 380C Derating factor is 0.91 Derated ampacity -> 36A >> 12.6A Case 2: Wire size 14 AWG 300C ampacity -> 25A Suppose the ambient temperature will rise to 600C Derating factor is 0.71 Derated ampacity -> 17.5A > 12.6A

Grid-Tied PV Systems – PV system engineering and design 1. Solar PV Inspection Walkthrough - Introduction https://www.youtube.com/watch?v=APrbl0Ngp8o 2. Solar PV Inspection Walkthrough - Inspector Safety https://www.youtube.com/watch?v=UfQvlpi-8Es 3. Solar PV Inspection Walkthrough - The Array https://www.youtube.com/watch?v=L5ilShww9h4 4. Solar PV Inspection Walkthrough - Combiner Boxes https://www.youtube.com/watch?v=nohKIGN4FxU 5. Solar PV Inspection Walkthrough - Wiring Methods https://www.youtube.com/watch?v=hbw5bUHf87Q 6. Solar PV Inspection Walkthrough - Inverters https://www.youtube.com/watch?v=kKy8Qg4FFZE 7. Solar PV Inspection Walkthrough - Interconnection https://www.youtube.com/watch?v=NvlVfEcmUZE 8. Solar PV Inspection Walkthrough - Following Up https://www.youtube.com/watch?v=ibgUZrvUdcE Penn State Solar Center