A New Utility Scale Solar Inverter & DC Collection System

September 15, 2011

• Nextronex Inc.• 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

• First Solar compatibility approval March 29, 2011

A New Utility Scale Solar Inverter & DC Collection System

• 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)

• Smart Grid Capability

A New Utility Scale Solar Inverter & DC Collection System

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

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 % dependingEnergy Harvesting on climate on climate

4. Operation and – – Maintenance Issues

% Improvement 5 % - 8 % Up to 20 %

% Improvement from Model

% Improvement from Actual Installations

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

Nextronex Linear Design

• (Photo of Nextronex Field Here)

Nextronex Cluster Design

• (Photo of Nextronex Field Here)

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

• 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 Perimeter InverterVoltage Drop with Center Inverter Cluster

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

• 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 & DC Collection System

Questions?

Contact Brandon Lohmeyer, Account Manager

Office: (567)225-3341

Email: brandon@nextronex.com