Solar PV and Storage Overview Sherry Stout, Engineer National Renewable Energy Laboratory (NREL) National Adaptation Forum Pre-Conference Workshop on Solar +Storage May 8, 2017
U.S. Solar Resource for tilt=local latitude Federal Energy Management Program; Renewable Energy Geospatial Screening Map Tool http://maps.nrel.gov/femp 2
Solar Photovoltaics (PV) Solar PV panels converts sunlight into DC electricity DC converted to AC by inverter There are no moving parts Solar and Agriculture Co-location at Massachusetts Test Facility 3
What does a resilient system look like? Source: https://nysolarmap.com/media/1655/dghubresiliencyretrofitfactsheet_8_8_16.pdf 4 4
What does a resilient system look like? Source: https://nysolarmap.com/media/1655/dghubresiliencyretrofitfactsheet_8_8_16.pdf 5 5
Types of Energy Storage Bulk Storage Good: Cost, large capacity Bad: Siting, lead time Distributed Storage Good: Siting, lead time, use options Bad: Cost Pumped Hydro Storage (PHS) Flywheels Compressed Air Energy Storage (CAES) Batteries: Flow Lead Acid Sodium Beta Lithium Ion 6
Energy Storage Market Growth Huge growth in Behind-the Meter Storage 60 MW Storage Deployed in 2015 GTM (2015) Energy Storage Monitor 7
Sharp Decrease in Battery Price Projections RMI (2014) Economics of Grid Defection 8
Energy Storage Economics in a Nutshell Energy storage: A bucket that moves energy from one time period to another Need to decide: o o o When to fill the bucket When to empty the bucket How big of a bucket to buy Factors to consider: o o o o How fast can the bucket be filled or emptied? How much does the bucket cost? How long will the bucket last? Will using the bucket in a certain way cause it to fail faster? The value of the energy must be worth more at the time you empty the bucket than it was at the time you filled the bucket. 9
Power vs. Energy Capacity Power o How fast you can charge or discharge the battery o Measured in kw or MW Energy Capacity o How much energy you have available o Measured in kwh or MWh Power : Energy ratio is primary specification for battery o Can generally specify the power : energy ratio Which of these buckets is more useful? 10
PV vs. Batteries PV is simple o Put it on the roof o The sun shines o Electricity is produced o Your utility bill is lowered Batteries are complicated o Put one in the basement or in a shed o Nothing happens Batteries can usually only do one thing at a time o To maximize Return on Investment, must determine what application battery should serve and when 11
Value Streams for Storage Opportunities for income and to avoid costs/losses Service Description Potential Value Grid Commercial Residential Demand charge reduction Energy arbitrage Demand response Resiliency / Back-up power Frequency regulation Capacity markets Use stored energy to reduce demand charges on utility bills Buying energy in off-peak hours, consuming during peak hours Utility programs that pay customers to lower demand during system peaks Using battery to sustain a critical load during grid outages Stabilize frequency on moment-to-moment basis Supply spinning, non-spinning reserves H H H H H M Voltage support Insert or absorb reactive power to maintain voltage ranges on distribution or transmission system L T&D Upgrade Deferral Deferring the need for transmission or distribution system upgrades, e.g. via system peak shaving Site specific 12
Energy Charge vs. Demand Charge 2,500 Grid Serving Load Electric Load 2,000 1,500 kw 1,000 500 0 Peak = demand (~2,000 kw on Thursday at noon) Area under curve = energy use (~285,600 kwh for week) Demand Charge: $15/kW for highest peak $15/kW x 2,000 kw = $30,000 Energy Charge: $0.11/kWh for all energy used $0.11/kWh x 285,600 kwh = $31,415 One week is shown here, but utilities determine and charge these on a monthly basis 13
Energy Savings from PV Generation 2,500 PV Serving Load Grid Serving Load Electric Load 2,000 1,500 kw 1,000 500 0 Peak = demand (~2,000 kw on Thursday at 5 pm) PV System producing 34,300 kwh/week Area under curve = energy use (~251,300 kwh for week) Demand Charge: $15/kW for highest peak $15/kW x 2,000 kw = $30,000 Energy Charge: $0.11/kWh for all energy used $0.11/kWh x 251,300 kwh = $27,643 Savings of $3,772/week 14
Demand Savings from Peak Shaving 2,500 2,000 PV Charging Storage Storage Discharging PV Serving Load Grid Serving Load Electric Load Battery is shaving down peak in afternoon/evening when PV is no longer producing electricity 1,500 kw 1,000 500 0 Peak = demand (~1,750 kw) PV System producing 34,300 kwh/week Area under curve = energy use (~251,300 kwh for week) Demand Charge: $15/kW for highest peak $15/kW x 1,750 kw = $26,250 Savings of $3,750/week Energy Charge: $0.11/kWh for all energy used $0.11/kWh x 251,300 kwh = $27,643 Savings of $3,772/week 15
Other Ways to Value Solar + Storage: Resilience 16
Value of Resiliency Many solar+ storage analyses do not factor in a value for resiliency How can resilience be factored in? 17
Value of Resiliency Source: Blackout: Extreme Weather, Climate Change and Power Outages. (Kenward & Raja 2014) 18
Value of Resiliency 19
Value of Resiliency Methods of valuing resiliency 1) Cost of an outage a. Individual Site Characterization (EPRI Outage Cost Estimation Guidebook Method) b. National Outage Survey (Interruption Cost Estimate Calculator Method) c. NY PRIZE Workbook (Societal Costs) d. Insurance valuation 2) Cost of other forms of emergency power a. Generator b. Combined Heat and Power c. Uninterruptable Power Supply 20
Value of Resiliency Methods of monetizing system resiliency 1) Monthly resiliency payment from site host 2) Reduction in insurance premiums 3) System incentive 4) Internal risk mitigation (contingency planning) 21
Value of Resiliency Estimating the Value of Resiliency Method *Macroscopic: Based on national estimates of past outage costs Used DOE ICE Calculator; key inputs: Customer type, location, average energy use, industry type, backup capabilities SAIFI: Average number of interruptions a customer experiences per year CAIDI: Average outage duration per utility customer affected 22
Value of Resiliency 5 Year Average Reliability Inputs Duration (CAIDI) Frequency (SAIFI) Radial 21.88 0.77 Network 50.96 0.04 Worst Storm Year in the Past 14 Years Duration (CAIDI) Frequency (SAIFI) Radial (2012) 73.5 1.39 Network (2012, 2007) 58.49 0.075 23
Example Site: Fire Station Utility Rate Maximum PV Size Load Size Resiliency Value Fire Station S.C. 91 Conventional Demand: $32.63/kW Energy: $0.0484/kWh in Summer $0.0434/kWh in Winter 10 kw Minimum Maximum Average Critical 2.86 kw 63.2 kw 15.2 kw 65% Hourly Value ($/hr/yr) Duration (hr/yr) Frequency (#/yr) Cost of Outage ($/yr) $917.43 21.88 0.77 $20,071 24
Example Scenarios NREL REopt Two Scenarios Scenario 1: PV + storage sized for economic savings; no resiliency requirement imposed Technologies Goal 1 Solar Storage Economic Savings Scenario 2: PV + storage sized to meet critical load 2 Solar Storage Resiliency 25
PV +Storage for Economic vs Resilience Savings Fire Station PV + Storage Sized for Economic Savings with and without Resilience Without resiliency value With resiliency value PV Size (kw-dc) 10 10 Battery Size (kwh) 43 213 Battery Size (kw) 16 31 Total Capital Cost $69,413 $172,741 NPV $22,365 $324,250 Simple Payback (years) 15.9 6.1 Percent of critical load system can support for 22 hour outage* 2-73% 47-264% *The level of resiliency provided by resilient PV systems sized for utility cost savings depends on when the outage occurs, state of charge of the battery, and load size 26
PV and Battery Reduce Peak Demand 27
PV +Storage Meeting Critical Load 28
Key Findings Including the cost of grid interruptions improves project economics o Value increases for customers with more frequent outages or longer outages Fire Station Without Resiliency With Resiliency PV Size (kw-dc) 10 10 Battery Size (kwh) 43 213 Battery Size (kw) 16 31 NPV $22,365 $324,250 $301,885 29
Key Takeaways Adding storage can improve PV project economics by reducing demand charges o Adding storage to city solar deployments could also be an opportunity to align the city s sustainability and resiliency goals PV+storage systems provide cost savings with some resiliency o Cost-effective due to high demand rates and shape of load o Sustaining full critical load with PV+storage is costprohibitive, however can sustain part of load for part of outage 30
Questions? Sherry.Stout@nrel.gov