- Nextronex has developed a new utility-scale solar inverter and DC collection system that aims to improve efficiency and reduce losses compared to traditional systems. - Their system received UL certification in 2010 and has been installed at several sites totaling over 6 MW. It uses distributed inverters, a smart controller, and other components to minimize losses from wiring and improve performance. - Nextronex claims their system can improve overall efficiency by 5-8% or up to 20% compared to traditional designs by reducing DC losses, improving inverter efficiency, and allowing for energy harvesting under low light conditions.

1. A New Utility Scale Solar Inverter & DC Collection System
September 15, 2011

2. A New Utility Scale Solar Inverter & DC Collection System
• 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

3. 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

4. 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 Single Line System
• Ungrounded DC operation for best
safety (with differential GFD)

5. PV Plant Loss Factors (exclusive of panels)
% Improvement % Improvement
from Model from Actual Installations
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 %

6. 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

7. 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 %

8. MPPT Performance
Clear day performance Cloudy day performance

9. Nextronex Linear Design
• (Photo of Nextronex Field Here)

10. Nextronex Cluster Design
• (Photo of Nextronex Field Here)

11. 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

12. The DC Wiring Problem
• Installed Cost is proportional to Cu weight
• Operating Cost is proportional to CU loss
• Three Approaches:
Constant Area (CA) Proportional Area (PA) Constant V drop (CVD)
- 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.

13. 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)

14. A New Utility Scale Solar Inverter and Wiring Topology
Voltage Drop with Center Inverter Cluster Voltage Drop with Perimeter Inverter

15. 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

16. 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

17. 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

18. A New Utility Scale Solar Inverter & DC Collection System
Questions?
Contact Brandon Lohmeyer, Account Manager
Office: (567)225-3341
Email: brandon@nextronex.com