DC MICROGRIDS A SOLAR BACK TO THE FUTURE

SOLHAROON, LEADSYSTEMSENGINEER, [email protected]

DECEMBER2012

DC M

ICROGRIDS

– A S

OLAR

“B

ACK TO

T

HE

F

UTURE

”

Making high-quality, high-power solar cells and modules using U.S.-based technology at affordable

A

GENDA

1. Overview of Suniva

2. Overview of PV Distributed Energy System Types 3. What is a Microgrid?

4. The Current Wars

5. What is a DC Microgrid?

6. Savings from a DC Microgrid 7. Examples of DC Microgrid

8. Case study of a Residential DC Microgrid 9. References

2 Confidential & Proprietary © Suniva®, Inc. 2012

S

UNIVA

- O

VERVIEW

Manufacturer of high-efficiency crystalline silicon PV cells and modules

– High-Efficiency Cells: 19% in production now; over 20% in laboratory; roadmap to

over 22% by 2014

– High-Power Modules: Up to 16+% in production; modules ranging from 235-315

watt

– Buy American Compliant: Our “Buy American” compliant modules are one of the

highest U.S.-content modules on the market

– Market focus: Commercial and utility applications in the U.S., Asia and Europe

– Top-Tier Customers: Solar City, Pro Logis, Sunetric, Fonroche, Reliance, Inman Solar,

Orion, AGT, UPS

– Manufacturing Capacity: 170 MW in the U.S.; 400 MW in Asia

– Cost Competitiveness: Cost competitive with top-tier Asian manufacturers

Headquarters: Norcross, Georgia (suburb of Atlanta)

Incorporated: 2007; Spun-out from Georgia Tech’s UCEP PV Center

Confidential & Proprietary © Suniva®, Inc. 2012

4

Deep Roots, Continued Collaboration

Established at Georgia Tech Department of Energy provided funding 1992: University Center of Excellence Established 2007: Suniva

S

® I

V

C

The solar cell is the “DNA” of any PV system, and hence the key driver of value

Silicon Ingot Wafer Systems

Integrators Cells Modules Balance of System Solutions Unique Partnerships

Confidential & Proprietary © Suniva®, Inc. 2012

6

B

ALANCE OF

S

YSTEMS

S

OLUTIONS

Suniva partners with the best-in-class inverter, mounting and battery storage/charge controller companies to streamline the balance of system selection process.

 Improve overall PV system performance

 Maximize kilowatt hours produced

 Reduce cost of PV ownership

 ARRA compliant

D

ISTRIBUTED

E

NERGY

: PV

SYSTEM TYPES

7

FOUR TYPES of SYSTEMS

[1] Grid-tie (“on-grid”) direct-power

[2] Off-grid battery-based

[3] Grid-tie (“on-grid”) battery back up

[4] Off-grid direct-power

D

ISTRIBUTED

E

NERGY

: PV

SYSTEM TYPES

8 Confidential & Proprietary © Suniva®, Inc. 2012

Standard Off-Grid System

D

ISTRIBUTED

E

NERGY

: PV

SYSTEM TYPES

Gridtie with Battery Backup

S

O JUST WHAT IS A

M

ICROGRID

?

A microgrid is a localized grouping of electricity sources and

loads that normally operates connected to and synchronous with the traditional centralized grid (macrogrid), but can disconnect and function autonomously as physical and/or economic

conditions dictate.

A microgrid offers “independence and profitability”

M

ICROGRIDS AND

S

MART

G

RIDS

12

1 Generation 2 Distribution 3 Storage

4 Loads 5 Control,

management, and monitoring

T

HE

C

URRENT

W

ARS

14

T

HE

C

ASE FOR A

DC M

ICROGRID

Most renewable distributed power generation today is DC. Ergo…use a DC backbone to connect the two.

Potential energy savings between 10% to 30%.

Energy Secretary Steven Chu: “America cannot build a 21st Century energy economy with a mid-20th _{century electricity system”}

A DC M

ICROGRID

C

ONSORTIUM

T

HE

C

ASE FOR A

DC M

ICROGRID

A DC microgrid is a microgrid that can co-exist with an AC power network but is based on DC power. Such a microgrid enables smart DC loads and enables the feed-in of distributed

renewable energy running natively in DC.

Advantages:

Enables smart DC loads to run with “native” power.

Synchronization of distributed generators are not necessary.

Ability to use distributed renewable energy sources that natively generated DC such as PV. The ability to use Class 2 NEC (National Electric Code) loads at non-lethal voltages (e.g. 24V). No power factor losses.

Loads are not affected by voltage sag, voltage swell, three-phase voltage unbalance, and voltage harmonics.

No inverter or transformer losses

DC-DC switching regulators can hit high efficiencies if required for certain loads Higher efficiency than AC microgrids also resulting in less thermal/heat wastage

DC M

ICROGRIDS WITHIN

B

UILDINGS

DC

AND

E

FFICIENCY

Yale School of Forestry and Environmental Studies

DC

AND

E

FFICIENCY

DC M

ICROGRID

B

UILDING

D

ISTRIBUTION

W

ORLDWIDE

E

XAMPLES OF

DC M

ICROGRIDS

E

: D

E

380VDC D

C

24

E

: D

E

380VDC D

C

W

HY

380V

26

24V DC D

ISTRIBUTION

NexTek Power and other companies are creating smart 24V DC distribution systems.

NEC Class 2 recognized. Under the 50V threshold.

Individual loads/devices typically consume 100W or less power yet deliver the same performance as older traditional devices

C

ASE

S

TUDY

: R

ESIDENTIAL

DC M

ICROGRID

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 A ~2000 square foot house

 Currently 6 Suniva 255 panels for around 1500W of PV.

 Expanding to 2000W and then to 4000W of PV

 12,000 WH of storage (4 GS Battery 246 AH 12V batteries arranged as 2S/2P for 24V)

C

ASE

S

TUDY

: R

ESIDENTIAL

DC M

ICROGRID

Lighting by Lighting Energy Depot

C

ASE

S

TUDY

: R

ESIDENTIAL

DC M

ICROGRID

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 Around 50W per room (15 x 20 feet room size) was needed to provide abundant illumination. Efficiency around 90 lumens per W

 Smart loads such as laptops and entertainment systems on DC

 Further studies are being done to log energy usage and generation

F

URTHER

D

EVELOPMENTS

 Standards continue to evolve as more vendors offer product and services

 Smarter Grids, More Distributed Energy, Smarter Loads

R

EFERENCES

>EmergeAlliance:

http://www.emergealliance.org/Resources/Presentations.aspx

>NexTek Power Design Guide:

http://www.nextekpower.com/support/Design_Guide_06-16-11.pdf

>Rebus™ specification:

http://rebuspower.com/REbus%20Microgrid%20Specification%20v0_ 14.pdf

>REIL: DC Microgrids: Benefits and Barriers

http://www.reilproject.org/05-DC-Microgrids%20%281%29.pdf

>EPRI Microgrids in General:

http://disgen.epri.com/downloads/15-DefiningMicrogrids.PDF 32

THANK YOU!

“I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that.”