AE Internal and Confidential

®

Sandia PV Performance

Modeling Workshop

May 5th 2014

Tucker Ruberti

AE Internal and Confidential

Inverter Performance Modeling Perspective

Three Categories of Opportunities:

1. Immediate Opportunities for Improvement

2. Emerging Needs that require heavy(ish) lifts

3. Intellectually interesting, but maybe not worth the effort

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AE Internal and Confidential

Creating an .OND file (aka Inverter model for PVsyst)

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AE Internal and Confidential

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Creating an .OND file (aka Inverter model for PVsyst)

AE Internal and Confidential

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Creating an .OND file (aka Inverter model for PVsyst)

AE Internal and Confidential

1. Immediate Opportunities for Improvement

A. Better efficiency curves input

I. Today: Best case is CEC default- 3 curves and 24 points

II. Better: Photon International- 275 points below

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AE Internal and Confidential

1. Immediate Opportunities for Improvement

B. 2-Stage Inverter Modeling

I. Today: very limited ability to model above/below maximum

power. Ex- 450 Vdc and above 850 Vdc below

II. Better: DC Voltage/Maximum Power curve, start-up/shut-

down behavior modeled more accurately

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AE Internal and Confidential

1. Immediate Opportunities for Improvement

C. Temperature derate/inflate I. Today: Must post-process inverter derate for high ambient

temp, or increase at low ambient temperature

II. Better: Ambient Temperature/Maximum AC Power Curve

D. 1500 Vdc System I. Today: Need to model as bi-polar. Must have even

number of modules per string

II. Better: Simply Add an option for 1500 Vdc systems

D. Multi-Orientation on one inverter I. Today: Need to model as 2 inverter

II. Better: Define 2 or 3 “arrays” for an inverter, even on a single MPPT tracker

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AE Internal and Confidential

2. Emerging Needs that require heavy(ish) lifts

A. AC Line Voltage Derate I. Today: Inverters can behave in VERY unexpected ways at

low AC line voltage, especially when there is low DC voltage, and reactive power demand

II. Better: Publish derate curves based on AC line voltage, at least for 1.0 PF

B Power Factor/Volt-Var/1547a/1547.8/Rule 21 I. Today: No way to account for “off-unity”, voltage support, or

other advanced inverter functions

II. Better: I don’t know… Variability makes this very complex

C. DC Coupled Storage I. Today: Exponential increase in requests for storage solutions,

but solutions providers have proprietary modeling tools

II. Better: Integrate storage into industry standard tools

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AE Internal and Confidential

3. Intellectually interesting, but maybe not worth the effort

A. Minute Level Data

I. Today: Hourly weather data, static AC line voltage, fixed PF

II. Better: At what point is more dynamic modeling valuable?

B Dynamic MPPT Efficiency

I. Today: Default for losses- No direct way to model MPPT

performance

II. Better: Dynamic MPPT data like IEC 53530? – Again, would

require minute level data, or better…

C. Reliability/Uptime

I. Today: Not accounted for directly for inverter

II. Better: Assign a default, start the conversation…

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AE Internal and Confidential

Conclusion: Real Barriers to Change

1. Manufacturers: Who moves first to share better data

publicly, not just for post-processing for large projects

2. Modeling Tools: investment and time to keep

improving inverter modeling as systems and

applications get more complex

1. …and getting good data from manufacturers

2. Maybe on an “opt-in” basis, otherwise use defaults

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AE Internal and Confidential

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800.446.9167

970.221.4670

sales.support@aei.com

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© 2014 Advanced Energy Industries, Inc. All rights reserved.

AE Internal and Confidential

Gaming PVsyst?

Selecting only DC voltages for curve input?

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