Integrating Solar and Storage: Learning from Success Susan M. - - PowerPoint PPT Presentation

1

Integrating Solar and Storage:

Learning from Success

1

Privileged and Confidential

Susan M. Buller Principal Strategic Analyst

2

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

PG&E and Our Business

3

• PG&E has 341,000+ solar customers,

more than any other U.S. utility

• PG&E adds 4,000 – 6,000 new solar

customers each month

• Industry-leading interconnection

speed averaging 1-3 days

• Engagement in solar policy and rate

reform discussions continue to highlight need for sustainable growth

• f solar that’s affordable for all

Rooftop Solar is (still) Growing Rapidly

Cumulative Retail Solar PV Capacity

PG&E has more than 20% of all U.S. rooftop PV installations and continues to support our customers who want to “go solar”

34% Avg. Year-over-Year Growth

500 1000 1500 2000 2500 3000 3500 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

MW-AC

Non-Res Residential

4

The Annual Peak Day (July 22) The Max 3-hour ramp in the Spring (March 13) The Highest 3-hour Ramp-Up in the Year (Dec.6) The Lowest Net Load in the Year (March 26)

Duck Elephant Dinosaur Alligator

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

Integrating Renewables Requires Flexible Resources

*Charts are illustrative of 2020 and 2022 forecasted inputs for CAISO. Subject to change after CAISO updates flexible capacity requirements.

5

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

6

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

• f AES.

7

Energy

Storage can “move” the renewable generation to more efficient time

How NEM Works

Solar Generation

Grid Power Grid Power Offsetting Onsite Load

Exports to Grid

• 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.

NEM with Storage

0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 Energy (kWh)

8

Storage + Solar

8

Privileged and Confidential

What could go wrong???

9

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

Case 1: DC-Coupled PV + Storage

10

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?

11

Case 1: Collaborating with Industry

PG&E Proposal for Test

• UL certification
• Firmware, not software, loss of

UL certification if firmware changed

• Draw from grid constrains

voltage below limit where charging could start (maintain system)

• Respond accurately when PV

fluctuates (intermittent cloud cover won’t over-ride non- import)

Final Result

• UL reports test results
• Firmware
• Storage in standby unless PV

export exceeds 1500 W for 30 seconds

• Responds accurately to PV

fluctuations

Remaining Challenge: UL Certification is not finalized because consensus process takes time

12

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

Case 1: Results

13

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

14

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

15

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

16

Questions?

16

Privileged and Confidential

Further questions:

Susan Buller 415-973-3710 smb4@pge.com