ewh.ieee.org r6 scv_pv_2012 june mark_b

©2008-2012 Enphase Energy

The Effects of Temperature on PV Systems

Mark BaldassariDirector, Codes and Standards

2©2008-2012 Enphase Energy | Confidential

Quick Introduction to Enphase

The Enphase Microinverter System

Effects of Temperature on PV Systems

Enphase Test Results

Questions

Agenda

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Introducing Enphase

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Headquarters in Petaluma California

Founded in March 2006

Publicly traded on NASDAQ (ENPH)

300+ employees worldwide

100+ patents filed or issued

Offices in United States, Canada, France, Italy, United Kingdom, New Zealand, and China

Our Company

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Enphase Evolution

Improving Performance & Simplifying Installation

1st Gen 2nd Gen 3rd Gen

94%95%

96%

2008 2009 - 2010 2011 - 2012

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Enphase Growth

> 43,000 Systems> 1,800,000 Units

“Microinverters are the fastest growing segment in the solar industry.” —Greentech Media

31% Market Share(CA residential)

0%

10%

20%

30%

2008 2009 2010 2011

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Enphase System

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End-to-End Solution

EnphaseMicroinverters

Envoy Gateway

EnlightenSoftware

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Grid-tied Microinverter

One Microinverter per PV Module

Per-module MPPT

Certified to: UL 1741, IEEE 1547, CSA C22.2

Rugged: – Environmental & lifecycle testing

beyond IEC 61215– NEMA6 (IP67) enclosure– -40 oC to +65 oC

M215 Microinverter

NetworkingMicroinverter Software

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Microinverter

‘Inverter on a Circuit Board’– One platform across portfolio– Economies of scale similar to hi-

tech electronics

Digital Power Control– “System on a chip” does sensing,

control & communication– High speed & precision enables

single-stage power conversion

SoftwareNetworking

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Powerful Networking– Monitors microinverters through

Powerline Communication– Bi-directional communications for

web-based management

Simple Setup– Auto-detection of microinverters– Plug and Play connection to

broadband router

Envoy Communication Gateway

Microinverter Networking Software

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Per-Module Monitoring– Monitors each module &

microinverter– Flexible views & graphs– No additional cost

Automated Reports & Alerts– Monthly email summaries– Automatic issue notification for

owner & installer

Enlighten Monitoring Software

SoftwareMicroinverter Networking

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Per-module Power ConversionMaximum Harvest

Performance

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Reliability

Unit & System Protected for

25 Years

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Simplicity

“All AC” Makes Installation

Fast & Flexible

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Safety

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High Voltage DC is a Danger for Firefighters

DC Disconnects are for Service Personnel and do Little for Firefighters

Safety to Prevent Fires

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Fire Danger

Up to 600 Volts DC!

Utility

Central/StringInverter

High Voltage DC DangersFaults pose serious risk of fire or electrocution

Sustained arc faults up to 2700 Degrees Celsius

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Microinverter safe for emergency workers

DC ~38 V AC

Microinverters & AC Electrical

Single Module

Utility

Load Center

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Safety

No High-Voltage DC Means

Safer Solar

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Effects of Temperature on PV

Systems

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Why is Temperature Important?

What is the Temperature Outside?

How Hot is it Under the Module?

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Power and Voc are inversely proportional to temperature

As temperature goes up, PV Power and Voc go down

Effect on PV Modules

0

5

10

15

20

25

30

35

40

45

50

0

50

100

150

200

250

300

350

-35 -25 -15 -5 5 15 25 35 45 55 65 75 85

Voc

(V

)

Po

wer

(W

)

Temperature (oC)

PV Power and Voc vs. Temperature

Power

Voc

P = Pmpp(1 + TC Pmpp(T - 25)/100)P = 235(1 - 0.45(T-25)/100)

Voc = Voc(1 + TC Voc(T - 25)/100)Voc = 37(1 - 0.37(T-25)/100)

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NFPA 70: NEC 2008 supplies ampacity tables and describes calculation methods

See Section 310.15 and Table 310.16

Effect on Conductor Ampacity

0

20

40

60

80

100

120

140

160

20 30 40 50 60 70 80 90Co

nd

uct

or

Am

pac

ity

(A)

Temperature (oC)

Conductor Ampactiy vs. Temperature

10 AWG

6 AWG

2 AWG

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NOAA, Weather Underground, iPhone apps, etc.

American Society of Heating, Refrigeration and Air-Conditioning Engineers, ASHRAE.org– Solar America Board for Codes and Standards,

SolarABCs.org

Determining Outside Ambient Temperature

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Measure temperature on typical residential Rooftop in Phoenix Arizona

Experiment

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Thermalcouples Mounted

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Data Collected

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Temperature Results

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Temperature affects PV Power and Voc

ASHRAE data is referenced in the NEC as a reliable source for historical temperature data

Temperature on the roof determines conductor ampacity, use the Code

Temperature under the PV module is not as hot as you might think

Conclusions

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Questions

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Experience Enphase