SEC 598 F 17 Photovoltaic Systems Engineering Session

SEC 598 F 17 Photovoltaic Systems Engineering Session 27 Residential PV System Case Study Construction, Inspection, Interconnection, Performance November 28, 2017

Session 27 - Value to class members • Additional evaluation and analysis of a residential grid-tied PV systems l l l Operation Life Cycle Costing Payback Analysis 2

Grid-Tied PV Systems – The Design Process Design Steps in a Residential Scale System 1. 2. 3. 4. 5. 6. 7. 8. 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 3

Grid-Tied PV Systems – The Design Process Step 4 – Securing relevant permits o Special overlay districts § o Zoning ordinances § o Construction practices; electrical enclosures, wiring, components Engineering approvals § o Setbacks, elevations, materials Building permits § o Architectural considerations Mechanical considerations Utility agreements § Connection arrangements; net metering rules; electrical signal quality 4

Step 4 – Securing relevant permits – P&D 5

Step 4 – Securing relevant permits – P&D 6

Grid-Tied PV Systems – The Design Process Step 4 – Securing relevant permits o Special overlay districts § o Zoning ordinances § o Construction practices; electrical enclosures, wiring, components Engineering approvals § o Setbacks, elevations, materials Building permits § o Architectural considerations Mechanical considerations Utility agreements § Connection arrangements; net metering rules; electrical signal quality 7

Grid-Tied PV Systems – The Design Process Step 4 – Utility Agreements o APS contracts and documents o o o Reservation to connect a homeowner’s generation facility to the APS Distribution System The Interconnection Requirements for Distributed Generation document Application to ensure that the PV system is qualified to participate (and have grandfathered rights) in the Net Metering Program 8

Grid-Tied PV Systems – The Design Process Step 5 – Construction Step 6 – Inspection Step 7 – Connection to the grid Step 8 – Performance monitoring 9

Step 5 - Construction

Step 5 - Construction

Grid-Tied PV Systems – The Design Process Step 5 – Construction Step 6 – Inspection Step 7 – Connection to the grid Step 8 – Performance monitoring 12

Step 6 – Inspections 13

Comparison of Two Residential PV Systems 5 k. W system installed in 2010 • • • Roof mounted 22 Siliken 225 W poly modules Sunny Boy 4 k. W inverter • • $1. 20/W (dc) Elevated structure 14 Canadian 250 W poly modules 14 Enphase micro-inverters • • • $3. 84/W (dc) Incentives: • • Enphase monitoring solution Installed cost: $13, 450 • Utility co. rebate: $13, 365 Federal ITC: $8, 694 State Solar Incentive: $1, 000 Total OOP Cost: $5, 920 • • $5. 85/W (dc) Incentives: • • No remote monitoring Installed cost: $28, 979 • 3. 5 k. W system to be installed in 2014 Installer rebate: $1, 000 Federal ITC: $4, 035 State Solar Incentive: $1, 000 Total OOP Cost: $7, 415 • $2. 12/W (dc) 14

Grid-Tied PV Systems – The Design Process Step 5 – Construction Step 6 – Inspection Step 7 – Connection to the grid Step 8 – Performance monitoring 15

Step 7 – Connect ion to the grid 16

Net Metering • At the end of each month, a utility bill is calculated: • • • Generation = N(k. Wh from utility) – N(k. Wh to utility) +/- N(credits from “energy bank”) This is all at the retail rate Once a year, the residual credits are cashed in • • This is all at the wholesale rate For APS solar customers, the “settle-up” date is 12/31 For SRP solar customers, the date is 04/30 This is a critical difference 17

Net Electrical Metering – Case 1 PV input = 0 PV system To House Loads Solar Meter Service Panel Utility Meter UM runs forward 18

Net Electrical Metering – Case 2 (Self-Consumption) PV input < Utility input PV system To House Loads Solar Meter Service Panel Utility Meter UM runs forward, but reduced 19

Net Electrical Metering – Case 3 (Power export) PV input > Utility input PV system To House Loads Solar Meter Service Panel Utility Meter UM runs in reverse 20

Grid-Tied PV Systems – The Design Process Step 5 – Construction Step 6 – Inspection Step 7 – Connection to the grid Step 8 – Performance monitoring 21

Recent Performance 22

Step 8 – Performance Monitoring 23

Step 8 – Performance monitoring on-peak - 14. 4 c/k. Wh; off-peak – 2. 3 c/k. Wh; average – 8 c/k. Wh All electricity costs – 12. 3 c/k. Wh 24

Step 8 – Performance monitoring 25

Step 8 – Performance monitoring APS Net Metering 26

Step 8 – Performance monitoring APS Net Metering – Generation Bill Avoided Electricity Cost = 0. 123$/k. Wh * 5225 k. Wh = $643 27

Step 8 – Performance monitoring SRP Net Metering Avoided Electricity Cost = $643 - $130 = $513 28

Current residential PV system example A spreadsheet was used to analyze this situation; plotting the results yields (for annual return) Net (Annual) $2, 000 $1, 000 $0 0 5 10 15 -$1, 000 -$2, 000 Cost • -$3, 000 -$4, 000 -$5, 000 -$6, 000 -$7, 000 -$8, 000 Year 20 25 30

Revised current residential Payback, APS vs SRP $12, 000 $10, 000 $8, 000 $6, 000 $4, 000 Cumulative (APS) $2, 000 Cumulative (SRP) $0 0 5 10 15 20 25 -$2, 000 -$4, 000 -$6, 000 -$8, 000 Year Payback –> 10. 5 – 13. 5 years 30