next105 ases power point presentation internal final

A New Utility Scale Solar Inverter and Wiring Topology

Peter GerhardingerChief Technology OfficerNextronex Energy Systems4400 Moline Martin RdMillbury Ohio 43447peterg@nextronex.com

May 18, 2010

Roger King, Ph.D.Professor, Electrical EngineeringUniversity of Toledo M.S. 3082801 W. Bancroft St.Toledo Ohio 43606rking@eng.utoledo.edu

A New Utility Scale Solar Inverter and Wiring Topology

• Nextronex Energy Systems, LLC

• Formed June 2008

• Initial Offering Closed November 2009

• 2nd Round currently Open

• Over $ 2 MM invested to date

• Inverter System received UL 1741 Certification June 2010

• First Installation May – July 2010 (399 kW, OANG Site)

• Two utility patents (and related foreign filings) pending

• Over 6 MW sold to date

Solar Inverters – Technical Approaches

• (Insert Inverter Matrix Slide here)

Nextronex Field

• (Photo of Nextronex Field Here)

A New Utility Scale Solar Inverter and Wiring Topology

• Nextronex has developed a unique kit of parts

containing everything needed from the string

wiring to the utility connection

• Low Profile 150 kW inverters

• Smart Controller

• Zone Boxes with Telemetry

• Power Strip(s)

• Load Center(s)

• All components UL listed for operation up to

1000 V dc

• Best-in-class 98 % + peak efficiency

• Distributed Architecture (M/S Switching)

PV Plant Loss Factors (exclusive of panels)

1. DC Wiring Losses, 2 % nominal Could be as high

Defects as 15 %

2. Equipment Efficiency 2 % nominal 2 % nominal

and Reliability

3. Low Light Level 1 % - 3 % depending 1 % - 3 % depending

Energy Harvesting on climate on climate

4. Operation and – –

Maintenance Issues

% Improvement 5 % - 8 % Up to 20 %

% Improvement

from Model

% Improvement

from Actual Installations

The DC Wiring Problem

• The DC collection system

represents a significant investment

in wire, connectors, and labor

• Problems are difficult to diagnose,

especially after commissioning

• Large variability if rows are long,

with many home runs (DC loss

increases with wire length)

• Commonly accepted 2% drop is

excessive for solar applications

The DC Wiring Problem

This is what you want to avoid

The DC Wiring Problem

• Installed Cost is proportional to Cu weight

• Operating Cost is proportional to CU loss

• Three Approaches:

- Constant area (CA) and constant V drop (CVD) have identical

power less, while proportional area has 25 % less loss.

- Proportional Area (PA) has the lowest power drop but the largest

variation in voltage drop.

Constant Area (CA) Proportional Area (PA) Constant V drop (CVD)

The DC Wiring Problem

• Conclusions:

• Volume of Cu needed is proportional to the square of the total current,

and the square of the linear dimensions

• For all cases, total power loss and voltage drop are inversely

proportional to the conductor volume

• Tapping the collection bus in the center results in 4x less copper volume

than tapping at and end point

-

-

Constant Area (CA) Proportional Area (PA) Constant V drop (CVD)

A New Utility Scale Solar Inverter and Wiring Topology

Voltage Drop with Center Inverter Cluster

A New Utility Scale Solar Inverter and Wiring Topology

Voltage Drop with Perimeter Inverter

A New Utility Scale Solar Inverter and Wiring Topology

Voltage Drop with Perimeter InverterVoltage Drop with Center Inverter Cluster

The Nextronex Solution

• Distributed Architecture

• 1000 V DC System (minimize IR Drop

and use 40 % fewer home runs)

• Low Profile Components for central

array placement

• DC Bus (Power Strip) with Integral

Zone boxes for very low loss, easy to

install and service DC collection

system

• Ungrounded DC operation for best

safety (with differential GFD)

Single Line System

Inverter Switching / Sequencing

• Before sunrise, the controller

chooses the lead inverter for the

day (rotated, based on run time)

• The lead inverter manages the

MPPT for that day, and the

remaining inverters are brought on-

line in slave mode as needed

• Ramp rate, step size, timing have

been worked out to insure accurate

MPPT, and to quickly respond to

cloud transients

Inverter & System Efficiency

• The Ray-Max Inverter has a peak

efficiency of 98 %

• Using the Nextronex Switching

Algorithm, a 1 MW system with 6

inverters reaches peak efficiency at

3% (30 kW) output, and will begin to

export power at 650 W

• The companion Load Center has a

peak efficiency greater than 98 %,

giving a system efficiency of 96 %

MPPT Performance

Clear day performance Cloudy day performance

The Importance of Information

• Without data, it is impossible to keep a

solar array in top condition

• Overall Power and Energy Output can

be assessed against weather data

• String level monitoring to quickly

address faults and keep your panel

mfgr honest

• Inverter and Transformer data for

predictive maintenance

• Advanced telemetry for timely updates

and remote monitoring

Operation and Maintenance

• Distributed Architecture for Fault Tolerance

and Reliability

• Modular Inverter Design – Replace Core

Inverter in 30 Minutes without shutting

system down

• Smart Controller provides the centralized

control, data, and telemetry point to monitor

system performance and respond to faults

and alarms

• Zone level monitoring and switching to

isolate problem strings for servicing without

shutting system down

The Smart Grid

• Utilities will need to control the output parameters of a solar

array if the promise of the “smart grid” is to be realized

• Curtailment to protect distribution and transmission lines

• VAR and Power Factor Correction

• Phase imbalance and brownout correction

• Shut-down verification for safety of line personnel

• The Nextronex Smart Controller provides the communication

point and our inverters are programmed to respond to

external commands

A New Utility Scale Solar Inverter and Wiring Topology

Questions?

A New Utility Scale Solar Inverter and Wiring Topology

Thank you