Increasing ROI With
Commercial-Scale Inverters
Sponsored By:
Before We Start
This webinar will be available afterwards at
www.solarpowerworldonline.com & via email
Q&A at the end of the presentation
Hashtag for this webinar: #SolarWebinar
Moderator
Presenters
Steven Bushong
Jon Fiorelli
Scott Kolek
Solar Power World
Solectria
Advanced Energy
Opportunities for Increasing
ROI of Commercial PV
Inverters
Scott Kolek – Product Manager - TX Inverters
AE Solar Energy
Agenda
Brief introduction to Advanced Energy
‘Typical’ Large-scale Commercial PV Installation
Technologies and Products for ROI Optimization
Traditional
New
Emerging
Conclusions and Takeaways
Advanced Energy Overview
30-year focus on power conversion solutions
• Founded in 1981 in Ft. Collins, Colorado
• 5 major sites: Fort Collins, Colorado; Bend, Oregon; Toronto, Ontario; Metzingen, Germany; and
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Shenzhen, China
1571 employees worldwide (as of May 2013)
Dedicated service organization
2012 revenue $452M
• Ended 2012 with $172.2M in cash, having generated $110.8M of cash in 2012
Market capitalization $676.42M (as of May 13, 2013)
• Two business units
• AE Thin Films: Power conversion solutions for thin-film plasma manufacturing
• AE Solar Energy: PV inverters and energy management solutions
• Solid footing in growing solar inverter market
• Leadership in North America
AE Solar Energy Global Footprint
Product Power Levels & Market Segments
String
Central
Integrated Solutions
Power: 12 – 24kW
Power: 35 – 500kW
Power: 500 – 2MW
Transformer and transformerless PV inverters, integrated solutions, complementary BoS products,
and O&M aimed at lowest cost of energy through project life-cycle
Traditional Large-scale Commercial PV Installation
Typical Characteristics
•
Rooftop mounted, 600 VDC Strings
•
~12 panels/circuit
•
DC Combiner Boxes
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Pad/Ground-mounted Central Inverters,
~100KW to 500KW range
•
DC:AC Ratio on order 1.1-1.25:1
•
DC Sub combiners (fuses or breakers) integral
to inverters
•
Inverter-level and (sometimes) sub combiner
monitoring
3MW Rooftop Solution, Ontario CA
250kW & 500KW Central Inverters
2.4MW Rooftop Solution, Portland OR
100kW & 260KW Central Inverters
Traditional Methods – ROI Improvement
BoS Cost Reductions
Increase Energy Harvest
 Structural system – optimized for
streamlined installation
 Increase panel performance
 Reduce install labor - pre-assembly, on-site
assembly line, etc.
 Increased inverter reliability & uptime
 Reduce O&M Costs – Reliability, increased
uptime
 Trackers
 Wiring reduction methods (CPT, RPT)
 MV Applications: Multiple inverters  1 Step
up transformer
 Inverters lifetime = module lifetime
 Increased inverter efficiency
 MPPT – Wider range, improved
algorithms
 Use of modeling for design optimization
New Methods – Distributed/String Inverters
ROI-Enhancing Benefits:
 Optimal match of power conversion capacity to
array capacity – using smaller 15-24kW inverter
blocks
 Eliminate DC Combiner Boxes (note: AC combiners
still required)
 Reduced cost of (commodity) AC aggregation
equipment versus low volume/high cost DC
equipment
 Less mounting space. Compact size allows closeproximity mounting to array. No pad or rigging.
 Multiple MPPT Trackers on each roof offset
shading & less-than-optimal array orientations
 Rapid field replacement serviceability
 Build-in monitoring capability for each inverter
100kW Rooftop Solution, Piscataway, NJ
20 & 24kW String Inverters
New Methods – High DC:AC Ratio Stringing
ROI-Enhancing Benefits:
 Low (and lowering) cost of panels
permit higher panel densities at
small overall cost impact
 Utilize higher DC:AC Ratios to
increase time at full power and
increase Capacity Factor (Actual
Energy / Max. Potential Energy)
 Achieve increased energy harvest in
high temperature climates and lessthan-optimal array mounting
configurations
 CEC efficiency & MPPT less relevant
in high DC:AC ration systems.
 DC:AC ratios 1.75-2:1 are available.
Emerging Methods – 1000V DC for Commercial
UL-Listed installations are happening
•
Utility, commercial ground mount and rooftop
Many developers & EPC’s going to 1kV DC
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Both central and string
Projected to become mainstream solution for large
commercial applications
No NEC barriers, AHJ roadblocks clearing
•
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1000 VDC on commercial rooftop and ground mount today
with minimal challenges
Ambiguity in code slowly being cleared up, acceptance
accelerating
1000 VDC equipment selection growing
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Driven by growth of Utility segment
Including modules, inverters, combiners, BOS
1000V DC Commercial PV – The Upsides, Downsides
ROI-Enhancing Benefits:
 20 modules per 1000 Vdc string vs. 12 per string at 600 Vdc in same location =
• ~40% less strings for same power, ~40% less combiner boxes, ~40% less home runs
 Conductor savings
• “Amps cost $, volts are free” : This is almost true, 1000 Vdc PV wire costs more that same
gauge 600 Vdc wire, but it carries far more energy
• ~40% less conductor costs.
• Lower voltage drop losses
• Less losses from strings to combiners
Downsides:
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Requirement to meet >600V (multiple) sections code can complicate AHJ approval
1000V equipment availability still biased towards large scale utility applications (but changing…)
Additional permitting and inspection “hoops” may offset benefits
Short cable length & restrictive wiring applications may limit benefits
Additional safety & training considerations for higher/1000V
Farther out – PV/Battery & Intelligent Microgrids
Concept:
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Battery storage + PV array
become ”dispatchable”
power supply asset
Enterprise Controls
intelligent dispatch
generation sources + load
controls to optimally-reduce
energy costs
Solar
PV
Battery
Storage
-
+
+
+
Inverter
Standby
Generators
Start/Stop
Load Level
Load Level
pF Level
Charge/
Discharge
Load Level
Facility Grid
Utility Supply
Reduce size and usage of
diesel gens for standby
power. Reduce UPS.
Participate in Energy
Markets and sell excess
electricity when prices high
Hybrid
PV/Battery
System
Enterprise
Level Control
…
Load
Shed/Add
PCC
Utility
Master
Control
Rev. meter,
Grid/Island
Facility
Loads
How AE is Addressing the Challenges
Continued Product Development
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1000V Solutions
Distributed/String solutions
Forward-thinking R&D and Technology Partnerships
•
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SEGIS-AC and SEGIS: 4 years and counting
• Partnering with industry leaders to develop collaborative solutions: PGE, PEPCO, SAFT,
NPPT, Sandia, NREL, etc
3+ year relationship with Schweitzer Engineering Lab (SEL) to advance technologies and
products related to utility, facility, and PV system integration
• Closed-loop controls, advanced anti-islanding, reliability and stability, cyber-security
Thinking beyond the Inverter
•
PowerStation packaging, hybrid power system, energy storage, advanced inverter master
controllers, etc.
Thank you for your attention!
Scott Kolek
Product Manager – TX Inverters
AE Solar Energy
+1.970.492.2028 Office
scott.kolek@aei.com
AE Solar Energy Headquarters
20720 Brinson Blvd
Bend, OR 97701
www.advanced-energy.com/solarenergy
Increasing ROI with
Commercial Scale Inverters
Jon Fiorelli
Applications Engineer
Solectria Renewables
jon.fiorelli@solectria.com
Topics Covered
1. Design Considerations…
2. Inverter Integrated Options…
3. Post-Inverter Installation
Considerations…
…that impact ROI
Design
Considerations
Design Considerations
 There are dozens of design decisions
 Cost/Benefit Analysis
 Financial Model
 Keep in mind that there are many
design decisions that are difficult to
quantify
 There are very few “Rules of Thumb”
 Project Goals and Challenges Vary
 Financial Models Vary
String Sizing
Use Max Allowable String Size to:

Reduced BOS Costs (Fewer strings means fewer combiner
boxes and fewer source and output circuits)

Reduce System Losses (fewer circuits and higher
voltage/lower total current)

Maximize Production for System Life Ensures that max
power voltage of the array will stay within the Max Power Point
Tracking range of inverter as modules degrade during the
lifetime of the system
Of course, using max. number of modules is not always
possible or preferred for other reasons (complex layout, odd
string size, carport…)
Next Stage in Design Evolution: 1000V Systems
String Sizing - Design Temperatures
Consider using…
ASHRAE Temperature (Extreme Annual
Mean Minimum Design Dry Bulb
Temperature) for larger max string size
 NEC 2011 690.7(A) Informational Note
 Read: “Array Voltage Considerations”,
B. Brooks, SolarPro Oct/Nov 2010
 CHECK WITH INSPECTOR!!
 SolarABC’s Map Tool
www.solarabcs.org/about/publications/
reports/expedited-permit/map/
String Sizing Example
Use Solectria PV System Builder (www.solren.com)
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Location: Atlantic City, NJ
Array Size: 600kW DC
Module: Sharp NU-U235F1
Inverter: PVI 500
Record Low/Average High
-23°C/29°C
 13 Modules Per String
 196 Strings
ASHRAE
-16°C/33°C
 14 Modules Per String
 182 Strings
THAT’S ONE LESS
14-STRING COMBINER!!
Oversizing
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Historically, designers oversize by 10% to 25%
optimize kWh/kW (Specific Yield) -> High Module
Prices
Times have change:
 Cheaper Module Prices (More production for less
incremental cost, same fixed cost)
 Time-of-Use Utility Rate structures
Limiting factor is short circuit current
Designers can vary tilt angle, power density, and
encroach into shaded regions
Definition of “Best” Ratio => Optimizes financial model
(IRR, NPV, LCOE)
Perform Oversizing Analysis using simulation program
(PVsyst, PV*SOL, SAM) which feeds financial model
Other Design Decisions
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Inverter Location (longest run DC or AC?)
Inverter Efficiency
Module Specs: Efficiency, IP rating, Loading specs
Module Tilt Angle/Orientation/Inter-row separation/Power
Density
 Small vs. Large Combiner Boxes
 Copper vs. Aluminum Wiring
Inverter Integrated
Options
Inverter Integrated Options
Save field labor, equipment costs, and
engineering/procurement overhead by having
inverter options factory integrated.
Examples:
 Subcombiners (Fuses, Breakers)
 Revenue Grade Meter
 Monitoring
 Gateway Card
 Zone Level Monitoring
(troubleshooting value)
 Same company for inverter/monitoring
(troubleshooting value)
Post-Installation
Considerations
Post Installation Considerations
Means to Ensure UPTIME and Minimize DOWNTIME
 Perform Preventative Maintenance
 Inverter Provider Preventative Maintenance Plans
 Inverter Provider Uptime Guarantee
 Monitoring with Fault Notification Alerts
 Fault Action Plan (Installer, O&M Provider, Inverter
Company)
 Spare Parts?? (Ground Fault Fuse, Subcombiner Fuses)
 Service and Maintenance Friendly Design (Site Plan
Placards, Shade structure, Service receptacles)
Thank You!
Jon Fiorelli – Applications Engineer
Jon.Fiorelli@Solectria.com
Don’t forget that Application Engineers can help increase ROI:
**Product Knowledge**
**Project Experience**
Questions?
Solar Power World
Solectria
sbushong@solarpowerworldonline.com
Phone: 440.234.4531
Twitter: @wtwh_renewables
Jon.Fiorelli@solectria.com
Phone: 949.933.6828
Steven Bushong
Advanced Energy
Scott Kolek
Scott.Kolek@aei.com
Phone: 1.970.492.2028
Jon Fiorelli
Thank You
 This webinar will be available at
www.solarpowerworldonline.com & email
 Tweet with hashtag #SolarWebinar
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