Carnegie Mellon University Evaluating Rooftop Solar Parity for Commercial Customers Shelly Hagerman, Paulina Jaramillo, M. Granger Morgan Carnegie Mellon University October 26, USAEE Pittsburgh 1

Carnegie Mellon University Previous Work Socket parity analysis – Residential Customers – Over 1,000 locations No SubsidiesFederal ITC Federal ITC + State 2

Carnegie Mellon University Are Commercial Customers at Parity? Different rate tariff structures Economies of scale in solar PV pricing Ability to finance Potential Adjustments – Load shifting – Change in tariff Source: NJR Clean Energy Ventures Source: Titan Solar Construction Source: Public Power Solutions Source: SbS Services 3

Carnegie Mellon University Timeline and Framework Initial Case Study Jun-Sep Expansion Oct-Nov Final Report Nov-Dec 4

Carnegie Mellon University Constructing an Initial Case Study Raleigh, North Carolina – Rapid commercial growth due to 35% state tax credit (Exp. 12/31/15) – Potential access to measured load and solar PV data Initial data inputs – DOE commercial reference building load profiles – Solar output model used in previous research – Reference tariffs 5

Carnegie Mellon University DOE Commercial Reference Building Profiles Hourly simulated data – Uses TMY data (same weather data as solar output model) 16 building types (2,500 sf – 500,000 sf) 16 climate zones 6

Carnegie Mellon University Primary Components of Commercial Rate Tariffs Customer Charge – Fixed, part of monthly minimum bill Demand Charges – Capacity based ($/kW) Flat, tiered, seasonal Energy Charges – Flat, tiered, hours of use ($/kWh) 7

Carnegie Mellon University PRELIMINARY RESULTS Initial Case Study 8

Carnegie Mellon University Commercial Customer Bills – Breakdown of Charges Larger Proportion from Demand Charges for Larger Customers and those on Time-of-Use Rates Default Time-of-Use SmallMediumLarge 9

Carnegie Mellon University Breakdown of Savings: Demand vs. Energy System Size: 10kW Installed Cost: $3.23/W 10

Carnegie Mellon University Demand Charges May Prohibit Economic Viability 11

Carnegie Mellon University Breakeven Costs between $1.50 and $2.10/W Above SunShot Initiative’s 2020 goal (positive NPV) Supermarket best, hospital worst 12

Carnegie Mellon University Preliminary Findings: Initial Case Study Small general service with time-of-use potentially most profitable NPV improves when peak demand coincident with solar Positive NPV by 2020 if SunShot goal is met 13

Carnegie Mellon University PRELIMINARY RESULTS Expansion 14

Carnegie Mellon University Expansion - Measured Data Load data – Currently: NC commercial load profiles (15-minute resolution) – Future: EPRI CA Office Building (1-minute resolution) Solar data – Currently: 1MW PV Plant in East, TN (1-minute resolution) – Future: 1MW PV Plant in NC 200kW PV Plant in CA (from same office building as load data) 15

Carnegie Mellon University Hourly Resolution Solar Data Can Both Overestimate and Underestimate Demand Savings in any Given Month 1-hr resolution solar data overestimated demand savings by an annual percentage difference of 28%, compared actual to 15-min averages 16

Carnegie Mellon University Next Steps Research questions: – Does rate structure matter? – Do hourly simulated data adequately estimate demand charges? – To what extent do building load profiles matter? – Can storage or demand-side management improve economics? Implications: – Provide framework for aggregating raw data to extend analysis to different locations – Contribute to discussion of financial viability of PV and rate reform 17

Carnegie Mellon University Acknowledgements Support for this work has come from NSF through the Center for Climate and Energy Decision Making under cooperative agreement SES , Carnegie Mellon Electricity Industry Center, and Electric Power Research Institute. 18

Carnegie Mellon University Thank you! Questions? 19

Carnegie Mellon University Solar Data Resolution Can Affect Demand Savings 20

Carnegie Mellon University Solar Data Resolution Can Affect Demand Savings 21