Solar Power International 2010

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Transformerless Inverters Presentation SMA

Solar Power International 2010

Transformerless Photovoltaic Inverter Technology

Addressing regulatory requirements in Product Development

Los Angeles/ October15, 2010


Disclaimer

This presentation may contain future predictions. Future predictions are statements that do not describe facts from the

past. They also contain assessments on our assumptions and expectations. These assessments are based on planning,

estimates, and forecasts, which are currently available to the SMA Solar Technology AG (SMA or company) board

of directors. Future predictions are therefore only applicable on the day on which they are made. It lies in the nature

of future predictions that they contain risks and elements of uncertainty. Various known and unknown risks,

uncertainties, and other factors may cause the actual results, financial situation, development, or performance of the

company to significantly deviate from the assessments provided in this presentation. These factors include those that

SMA has described in published reports, which are available on the website www.SMA.de. The company assumes

no liability for updating or adjusting such future predictions in accordance with future events or developments.

This presentation serves informational purposes only and does not constitute an offer or request to buy, keep, or sell

company shares.

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

Presentation Outline

1. Introduction SMA Solar Technology

2. Transformerless Technology: Overview

3. Transformerless Inverters: Design Principles

4. Transfomerless Inverter Installations

5. Summary

Presented by:

Joanna Marienhagen

SMA Solar Technology AG

Operational Product Manager Sunny Boy

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1. SMA Solar Technology

4


1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

SMA is market and technology leader for PV inverters

All PV applications All performance ranges All module types

On-grid

Off-grid

Back-up

From 1 MW

Thin

film

Crystalline

modules

Concentrator

modules

8 SMA offers inverters for all applications in photovoltaics

5


1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

SMA Key Facts

> Founded in 1981

> 3.4 gigawatt annual production (2009)

> Globally more than 5.500 employees

> 13 foreign subsidiaries in 12 countries

on four continents

> 2 manufacturing locations: Niestetal

Germany and Denver, CO

> Best efficiency worldwide (98.7 %)

> First UL-listed SMA inverter in 2002

> Participant in UL Client data test

program

Service location

Sales & Service

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2. Transformerless Technology

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Technology: Benefits

1

High conversion efficiency – High Yields

2

Reduction of components

3

Safety

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Technology: Comparison

Inverter with (LF) transformer

L1

Inverter without transformer

60 Hz/

16kHz

60

Hz

L2

Installation with grounding

Installation without grounding

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Technology: Requirements in UL1741 CRD

> Insulation Resistance Detection(§90)

> Measure insulation resistance prior to connection

> Detect values below limits

> Prohibit connection if measured values below limit

> PV Array Isolation Monitor Interrupter (§89)

> Continously monitor for isolation fault current and sudden

changes of current

> If limits exceeded threshold, disconnect and limit

automatic re-connection

> Provide single component fault safety

> Automatic Disconnection System (§92)

> Provide means to disconnect current-carrying conductors

> Monitor isolation prior to connection

> Prohibit connection if critical isolation components fail

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3. TL Inverter Design Principles

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Insulation Resistance Monitoring

RISO Measurement to detect a potential ground fault

Principle:

RISO

Measurement

Circuit

> Voltage measurement between each the positive

and negative terminal of a string and neutral/

ground.

> Measured voltage difference indicates a Residual

Current / Ground Fault

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Insulation Resistance Monitoring

Functionality:

> Measure insulation resistance prior to

connection

RISO

Measurement

Circuit

> If values below limit – no connection

Advantages:

> Detects insulation defects prior to connection

> Detects „symmetrical“ ground faults

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Isolation Monitoring

Differential Current Measurement to detect

leakage current

Principle:

Residual

Current

Monitoring

Unit

> Measurement of magnetic field

> Changes of magnetic field indicate a fault

current (IF)

Definition: Differential current (DI)

= Capacitive discharge current (ICD) + Fault

current (IF)

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Isolation Monitoring

Functionality:

> Upon connection to grid, the Differencial Current

(DI) is continuously monitored

> Disconnection if values exceed the threshold:

Residual

Current

Monitoring

Unit

> DI > 100mA

> Delta DI > 30mA

Advantages:

> More sensitive: detects fault currents >30mA

> Detects „undesired“ connection to ground

> Self-Monitoring

> No connection, if measurement range

insufficient to detect fault currents

> Permanent disconnection if more than four IF

events/ day

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Separation

Continuous monitoring to prevent DC on AC side

> Principle:

> Control Switching of IGBTs

> Measure AC current

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Design Principle: Separation

> Functionality:

RCMU

V AC

f AC

(D)D

I

UL1741, IEEE 1547

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4. TL Inverter Installations

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Installation Requirements

Ungrounded PV Array

> When using a combiner box with multiple strings, DC overcurrent protection is

required in both DC conductors (+ and -)

> DC switch disconnects both conductors (+ and -)

> No array grounding – no white conductor

> Double-insulated PV wire

Fused Combiner Box

Inverter with

DC Disconnect

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Installation Practices

Markings

> Ungrounded PV arrays are accepted by UL and NEC.

> As not very common in the US a warning is required.

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

TL Inverter Technology: Summary & Outlook

1

TL technology offers benefits in system efficiency

2

TL inverter technology is safe

3

Worldwide more than 1 million TL PV installations

TL technology will increase in popularity in the US

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1. SMA Solar Technology | 2. TL Technology | 3. TL Inverter Design Principles| 4. TL Inverter Installations | 5. Summary

SUNNY BOY TL-US: Technical Data

SUNNY BOY 8000TL-US/ 9000TL-US/ 10000TL-US

Nominal Power

Application/ Segment

Topology

8kW/ 9 kW/ 10 kW

Commercial – 208 V WYE Net

Transformerless

Input Values:

DC Voltage Range: Input/MPP

Max. DC Current

300 – 600 V/ 300 – 480 V

34 A

Output Values:

Max. AC Current

48 A

CEC Efficiency 98.0%/ 98.0%/ 97.5 %

Enclosure and Components

Aluminum Diecast

Attached DC Disconnect

External Fused Combiner Box


THANK YOU!

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