1 Integrating Solar and Storage: Learning from Success Susan M. Buller Principal Strategic Analyst 1 Privileged and Confidential
PG&E and Our Business Company Facts Fortune 200 company located in San Francisco, CA $15.6B in operating revenues in 2013 Over 22,000 employees Energy Supply Services to 15M people: 5.2M Electric accounts • • 4.3M Natural Gas accounts Peak electricity demand: Approx. 22,000 MW Approx. 70% of PG&E’s electric supply comes from non-greenhouse gas emitting facilities – 33% from renewable Service Territory 70,000 sq. miles with diverse topography 160,000 circuit miles of electric transmission and distribution lines 49,000 miles of natural gas transmission and distribution pipelines 2
Rooftop Solar is (still) Growing Rapidly PG&E has more than 20% of all U.S. rooftop PV installations and continues to support our customers who want to “go solar” Cumulative Retail Solar PV Capacity • PG&E has 341,000+ solar customers, 34% Avg. Year-over-Year more than any other U.S. utility Growth 3500 • PG&E adds 4,000 – 6,000 new solar 3000 customers each month 2500 • Industry-leading interconnection 2000 MW-AC speed averaging 1-3 days 1500 • Engagement in solar policy and rate 1000 reform discussions continue to 500 highlight need for sustainable growth of solar that’s affordable for all 0 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Non-Res Residential 3
Integrating Renewables Requires Flexible Resources Only spring and winter days look like a duck Summer days require more capacity than “duck” days Need for flexible capacity that can adapt to changing load curve Dinosaur The Max 3-hour ramp in the Spring (March 13) Elephant The Annual Peak Day (July 22) Duck Alligator The Highest 3-hour Ramp-Up in the Year (Dec.6) The Lowest Net Load in the Year (March 26) *Charts are illustrative of 2020 and 2022 forecasted inputs for CAISO. Subject to change after CAISO updates flexible capacity requirements. 4
Customer Storage: a brief history The first PG&E customer behind-the-meter (BTM) storage was interconnected October 28, 2011. 1MW battery installed in the SF Bay Area This was the first incentive from our Self Generation Incentive Program. Paid on March 22, 2012. Approx. $2M incentive. Generally storage is installed by our customers to: Reduce demand charges; “peak shaving” Rate arbitrage; “move” solar power to evening hours PG&E has paid 314 battery projects; +25MW; $45M incentives 5
Energy Storage; Case Studies PG&E analyzed many of our customers’ storage charge & discharge patterns, their utility rate and considered grid emissions, to determine economic and environmental impacts of AES. 6
Storage can “move” the renewable generation to more efficient time How NEM Works NEM with Storage 5 4,5 4 Solar Generation Energy (kWh) 3,5 3 Energy Exports to Grid 2,5 2 1,5 Grid Power 1 Offsetting Onsite Load 0,5 Grid Power 0 • By 2020 electricity customers in California will be on Time-of-Use rates where the highest rate will be from 5-10 or 4-9 on week days. • Energy costs in California are driven by the cost to serve net load (customer demand not bet through intermittent, as available power from renewable resources). This means that as the sun sets, energy costs increase • Storage can help a customer “move” their solar production to the time when costs are higher. • This means more load during daylight, which means less curtailment of solar generation. It also means less load in the evening, so less use of natural gas generation. Overall should lead to lower GHG emissions. 7
8 Storage + Solar What could go wrong??? 8 Privileged and Confidential
Case 1: DC-Coupled PV + Storage Value Proposition: • Combine PV with Storage to shift renewable power for use at a later time • Increased efficiency of PV + Storage (DC from PV to DC in Storage) The Problem: • NEM is for renewable energy and it is difficult to ensure that the storage in a DC- coupled configuration doesn’t charge from the grid to then later discharge for NEM credits • A metering solution (as used in NEM- MT) doesn’t work, because PG&E does not currently use DC meters • A physical relay is not preferred because of cost and because storage has auxiliary load (e.g. pumps, fans, control system) that could be served by grid power 9
Case 1: Implementing a Proposed Solution Proposal from NEXTracker and CalSSA (then CalSEIA) • Set storage device to charge only above certain voltage • Utilizes inverter-based technology to sense power flow and adjust voltage on DC side accordingly – When power flows toward the grid (when PV is generating), voltage is adjusted up so storage is able to charge – When power flows toward the storage (PV not generating), voltage is adjusted down so that the storage device is unable to charge – Low voltage power is still able to serve battery auxiliary load (e.g. pumps, fans, control system) Implementation Concerns • How do we ensure equipment performed as designed without need for constant monitoring? • How do we generalize a compliance test, so that the engineers don’t have to do one -off reviews? – How do we make sure that test is NOT only just for NEXTracker? 10
Case 1: Collaborating with Industry PG&E Proposal for Test Final Result UL certification UL reports test results Firmware, not software, loss of Firmware UL certification if firmware Storage in standby unless PV changed export exceeds 1500 W for 30 Draw from grid constrains seconds voltage below limit where Responds accurately to PV charging could start (maintain fluctuations system) Respond accurately when PV fluctuates (intermittent cloud cover won’t over -ride non- import) Remaining Challenge: UL Certification is not finalized because consensus process takes time 11
Case 1: Results Interim Fix: • Joint-IOU and Industry stakeholder created compliance tests is outlined in our Distribution Interconnection Handbook for UL to use to conduct compliance test Long-term Objective: • Replace compliance test with UL certification (e.g. UL-####) Impact • Enabled a PV + Storage solution that: • Protect the integrity of NEM – ensuring NEM credits given only for renewable energy • Operationally efficient to administer • Easy for customers to understand • Commission support and appreciates consensus solution 12
Case 2: Storage GHG Emissions Self Generation Incentive Program (SGIP) designed by Legislature to reduce GHG emissions Program Performance As of March, 2018, 7% of SGIP funds went to storage installations ($45M / $640M); 314 projects (of 1,225), and 25.2MW installed capacity (of 315MW installed total). Eligibility Requirements RTE at least 69.6% Capacity up to annual peak demand 130 full discharges/year (nonres); 52 discharges/year (Res) When paired with renewable, ITC or equivalent fuel requirement Problem: On average, storage increased GHG California grid starts with low emissions Economic signal inefficient 13
Case 2: Solution California Public Utilities Commission Mandated “ GHG Signal Working Group ” Utilities, CPUC staff, equipment vendors, consultants Model storage to recommend program changes: Data intensive, 8760 grid emissions, customer load shapes Several models, incl. “open source”, common assumptions Model three cases: BAU, Constraints, GHG ME Rate Signal Apples to apples output: Net GHG impacts; Customer bill savings; Grid Savings; Battery lifetime impacts; Annual RTE Analysis Overall GHG performance; by customer savings; incentive amounts; grid costs; Signal infrastructure costs Recommendations: TBD 14
Lessons Learned – From Success Include All Concerned Stakeholders Identify Common Interests Clarify Concerns Clearly state and explain limitations Listen to explanations Bring in the Engineers Persist 15
16 Questions? Further questions: Susan Buller 415-973-3710 smb4@pge.com 16 Privileged and Confidential
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