The document discusses issues with high penetration of photovoltaics (PV) and the role of energy storage solutions. High PV penetration can cause problems with generation mix, instability on high-penetration feeders, and reverse power flows. Storage can help integrate more PV by smoothing output over seconds/minutes and shaping output over an hour to conform with forecasts. Locating storage near PV or consumers maximizes value. Optimizing energy storage requires minimizing costs while capturing multiple value streams like peak shaving and grid services to allow higher levels of renewable energy on the grid.

1. Supporting High-Penetration PV
with Energy Storage
Photovoltaics Summit 2011
Scottsdale, AZ

2. Outline
Drivers for PV
Issues with high-penetration PV
Energy storage solutions
Photovoltaics Summit 2011

3. RPS Policies
www.dsireusa.org / December 2010
VT: (1) RE meets any increase ME: 30% x 2000
WA: 15% x 2020* New RE: 10% x 2017
MN: 25% x 2025 in retail sales x 2012;
MT: 15% x 2015 (Xcel: 30% x 2020) (2) 20% RE & CHP x 2017 NH: 23.8% x 2025
OR: 25% x 2025 (large utilities)* ND: 10% x 2015 MI: 10% + 1,100 MW MA: 22.1% x 2020
5% - 10% x 2025 (smaller utilities) x 2015* New RE: 15% x 2020
(+1% annually thereafter)
SD: 10% x 2015 WI: Varies by utility;
NY: 29% x 2015 RI: 16% x 2020
10% x 2015 statewide
NV: 25% x 2025* CT: 23% x 2020
IA: 105 MW OH: 25% x 2025†
CO: 30% by 2020 (IOUs) PA: ~18% x 2021†
10% by 2020 (co-ops & large munis)*
IL: 25% x 2025 WV: 25% x 2025*† NJ: 22.5% x 2021
CA: 33% x 2020 UT: 20% by 2025* KS: 20% x 2020 VA: 15% x 2025* MD: 20% x 2022
MO: 15% x 2021 DE: 25% x 2026*
AZ: 15% x 2025
OK: 15% x 2015 NC: 12.5% x 2021 (IOUs) DC DC: 20% x 2020
10% x 2018 (co-ops & munis)
NM: 20% x 2020 (IOUs)
10% x 2020 (co-ops)
PR: 20% x 2035
TX: 5,880 MW x 2015
HI: 40% x 2030
29 states +
Renewable portfolio standard Minimum solar or customer-sited requirement DC and PR have
Renewable portfolio goal an RPS
Solar water heating eligible *
†
Extra credit for solar or customer-sited renewables
Includes non-renewable alternative resources
(7 states have goals)

4. Compatibility with electricity networks
Macro level
Generation mix
Micro level
High-penetration feeders
Island systems
Photovoltaics Summit 2011

5. Generation mix – 1
How do Wind and Solar Power Affect Grid
Operations: The Western Wind and Solar
Integration Study
NREL/CP-550-46517
Photovoltaics Summit 2011

6. Generation mix – 2
Summer
“The Role of Energy Storage in
the Modern Low-Carbon Grid”
Paul Denholm - NREL
Spring
2000 Normal
Min Load
16 GW simulated PV system
providing 11% of system’s energy
Photovoltaics Summit 2011

7. PV peak vs. system peak
Photovoltaics Summit 2011

8. Localized instability
Issues with high-
penetration feeders
Fast ramp rates cause
voltage fluctuations
Potential for reverse
power flows through
substation
Source: Aerowatt
Major problems in island
networks
Photovoltaics Summit 2011

9. The role of energy storage
Provides good value but non-essential for mainland
grid operations at present
Will become essential as renewable penetration
increases
Three fundamental “S” actions
Seconds / minutes – Smoothing
~1 hour – Shaping
Hours – Shifting
Photovoltaics Summit 2011

10. Smoothing and shaping PV farm output
Storage of ~20% of daily PV output Worst-case scenario
Smoothed injection to grid
Conformance to forecast output PV output
(actual)
PV + storage
(forecast)
PV + storage
Example:
(actual)
Per MW of PV rating
0.5 to 1 MW battery power
0.5 to 1 MWh battery energy
20 ft. container
1.1 MW for 30 minutes
Photovoltaics Summit 2011

11. Location of storage
Storage co-located with PV?
Makes sense for high-penetration feeder
Locate storage close to consumer wherever possible
Provides maximum value
Local options
Residential storage
(with rooftop PV)
Community energy storage
Photovoltaics Summit 2011

12. SMUD Anatolia III project
ARRA FOA 85 Topic 4: High penetration
solar development
Installing 15 RES and 3 CES units in
Anatolia ‘SolarSmart’ Homes that
currently have 2kW PV systems
Installing utility and customer portals to
monitor PV, storage, customer load
Sending price signals to effect changes
in customer usage
Developing specification for smart
meter/inverter interface to enable
management of distributed PV/storage
system with AMI
Saft is storage partner using advanced
Li-ion technology developed for EV
Photovoltaics Summit 2011

13. Optimizing value from PV storage
Minimize cost of storage
Synergies with EV applications for Li-ion
Storage requirements
Maximum life
Wide operating state of charge range
Very high efficiency (>95% dc)
Maximize value streams
Residential PV shifting to avoid peak rates
Power reliability – islanding / microgrids
Participation in demand-response programs
Night-time ancillary services
Photovoltaics Summit 2011

14. Summary
Energy storage provides the solution to PV integration
issues, allowing higher penetration levels
The cost of energy storage can be mitigated by
addressing multiple value streams
Li-ion battery storage leverages synergies with EV
Photovoltaics Summit 2011

15. Thanks for listening!
jim.mcdowall@saftbatteries.com
Photovoltaics Summit 2011