1. Grid-Interactive Systems
“A matter of energy storage”
Dr. Jeffery Lee Johnson
CTO Todo-Solar
Coahuila, México
Email: jeff.johnson@todo-solar.com-mx Tele: (+52) 871 722 9522 www.todo-solar.com.mx

2. Agenda
• Seasoned Sentiments
• What is a Grid Interactive system?
– Best explained by what it is not
– Definition of a true grid-interactive PV System
• Examples of Grid Interactive systems
• Why are Grid Interactive systems of interest to installers?
• Seeing the Bigger picture
– Centralized versus Distributed Systems
• Addressing the larger questions
– Why grid interactive systems ?
– What will be the evolving role of Energy Storage for next
generation PV system
• Summary and questions

3. Doc Solstice’s Seasoned Sentiments
Let’s examine the limit in which by some miracle
tomorrow morning we had access to an unlimited
source of free clean energy.
Would this be a sustainable scenario?

4. Doc Solstice’s Seasoned Sentiments
Let’s examine the limit in which by some miracle
tomorrow morning we had access to an unlimited
source of free clean energy.
Would this be a sustainable scenario?
No! This would not be a sustainable scenario !
Sustainability represents far more than just our
source of energy. It includes:
 Energy delivery and storage systems
 Intelligent and efficient use of energy
 Smart Grids
 Impact of energy use on other resources
Global and local economics

5. Most familiar types of modern PV
systems are Off-Grid and Grid-connected
#SolarMOOC webinar by Kenny Grigar on Off-Grid Systems Introduction to the #SolarMOOC Academy & many other
http://www.youtube.com/watch?v=65yV7rPRreA http://www.youtube.com/watch?v=76UZnghX9Dg
 Wholly Grid independent  Wholly Grid Dependent
 Used where Grid is limited or non-existent  Used where Grid is reliable
 Market is mostly developing economies  Fastest growing PV Market
 Enabling Event is affordable storage  Enabling Event is net metering

6. Grid Connected with Battery Backup
(GCBB) is a Hybrid System
IN SOME CASES, THESE
ARE TWO SEPARATE
INVERTERS

7. Another Example of GCBB

8. The key issues for GCBB are Cost and
Operational mode
• These systems require more components and storage which
elevates cost
• Sometimes referred to as “Grid Interactive”, but it is not as
what is meant here
• Energy is stored for “later use” but not necessarily as needed
– Backup kicks in when grid is down
– Usually backups specific AC circuits or DC loads
• Requires more sophisticated design rules and additional
installation

9. What is a true Grid Interactive PV System ?
• Similar to GCBB systems but more formally it is defined as
“Grid Connected System with Intelligent Energy Storage”
• Hybrid of Intelligent Storage and integrated Inverter
– Applies stored energy as needed or upon demand (such as at night,
cloudy days etc.) independent of Grid status
– Uses various energy storage devices such as improved Lithium Ion
Batteries or Fuel cells
– Optimizes private consumption for a “consumer-controlled net
metering scheme”
– Affordable technology is just now emerging (June 2012)
– Adds flexibility to PV systems design with respect to production
– With flexibility come complexity !

10. The Emergence of Intelligent Storage
http://www.schottsolar.com/global/news/top-news/article/schott-storeitTM-2/
SCHOTT STOREIT™
 High-performance battery pack of lithium-ion
cells, a PV inverter, a battery inverter and an
energy management system.
Easily connects with the existing house
network with need to connect individual
components.
 Energy management system controls how
much of the electricity generated by the PV
system is actually used for private
consumption, stored inside the battery or fed
into the Grid
SCHOTT will unveil its
 The battery basically serves as an electricity storage concept,
the SCHOTT STOREIT, at the
intermediate storage device for the PV electricity
Intersolar EuropeTrade Show
generated during the day, which the system in Munich, June 13th-15th,
owner can then used at a time when needed. 2012.

11. Schematic of a Grid Interactive system
Power Generation
Meter Monitor
PV Production Bidirectional Meter
Random Grid
consumption or
Load

12. Fronius Energy Cell
http://www.fronius.com/cps/rde/xchg/SID-05807842-8029BBDE/fronius_usa/hs.xsl/2714_1586.htm
The core of this concept is a
hybrid fuel cell with integrated
inverter electronics

13. The Basics of Fuel Cell
• Hydrogen is separated from water
using “hydrolysis”
– Solar Energy is converted into
electrochemical energy
• Hydrogen is passed through a
catalyst membrane that strips off
the electron
• Negative cathode is charged,
positive protons are attracted to
positive cathode creating a
“battery”
• To discharge, electrons are
reunited with the hydrogen
protons.
• Hydrogen atoms are passively
recombined with O2 with a
byproduct of water

14. Why are Grid Interactive Systems
important to installers ?
• Sooner or later, installers will have to deal with the
design and installation
• Procedures and Processes will evolve with technology,
especially energy storage
• Energy storage is already on the renewable energy
roadmap
– High priority now for Utility Scale projects
– Future Smart Grid architecture calls for energy storage at all
levels including residential
– Prices for main components have dropped to where energy
storage costs are “well above radar” and are being addressed
Hey, the Germans are once again taking the lead and
doing it, I tend to trust the German Solar industry

15. Utility Scale Solar does not address issues related
to centralization: Storage and Distribution
Traditional Central Plant Solar PV Central Plant
Energy is
stored in Fuel
?
Oversized Distribution Grid = Energy loss (8.5% and rising)

16. Energy Storage shaves Load

17. Advantages of Distributed Systems
• Distributed systems are a network
of individual “mini-plants” using
renewable energy
-- homes, businesses, small solar farms,
community solar parks etc
• Energy is created near or at point of
consumption (true even with net
metering)
• Generally takes advantages of dual
purpose land
– Big Box Rooftops, residential, revitalized
land (such as landfills), schools etc
• Still depends on Grid network and
hence, ENERGY STORAGE

18. From the Macro to the Micro: Smart
Distributed Systems (Residential)
Many technologies must and will merge to form the ideal integrated system

19. Characteristics of a home
system with storage

20. The future will depend on smart storage and intelligent
distribution at both Centralized and Distributed levels

21. Summary
• Solar Energy is in its infancy
• The renewable energy roadmap is being drawn out
to 2020, 2030, 2050 and beyond
• To replace existing needs and provide future
needs, We need to get smart about energy
storage, energy distribution, energy use and all
natural resources including land
"We can't solve problems by using the same kind of
thinking we used when we created them.“ A. Einstein

22. (Solar Energy made available to Everyone)
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