2014 PV Performance Modeling Workshop: Optimizing PV Designs with HelioScope: Paul Gibbs, Folsom Labs

1. Optimizing PV Designs with HelioScope
Sandia Performance Modeling Workshop
Paul Gibbs
May 5, 2014
paul.gibbs@folsomlabs.com

2. Agenda
• What is HelioScope and why is it good for
optimization?
• Case Studies in PV System Optimization
– Ground Coverage Ratio
– DC Plant Design
– Designing into Shade
• Looking forward: automating optimization

3. HelioScope is a design-driven PV modeling tool
Principles
• Design-driven
• Component-level
• Cloud-based
Values
• Throughput Velocity
• Value Engineering

4. HelioScope Tour: Adding a Field Segment

5. HelioScope Tour: Modifying an Array

6. HelioScope Tour: Generating Wiring

7. Production reports include a full bill-of-materials
Performance Modeling:
• Full Loss Tree
• Condition Set Details
• Hourly Data CSV
Design Specifications:
• Bill-of-materials
• System Layout
• Wiring Details

8. Why is HelioScope ideal for optimization?
• Rule Based: Trivial to evaluate design alternatives
• Design Driven: Bill-of-materials generated automatically
• Granular Modeling: Performance model always in sync with design
180º Azimuth (Due South) 205º Azimuth

9. We designed our interface specifically to
encourage value-engineering
Designs
Conditions

10. GCR optimization is an ideal area for
optimization
Key Issues:
• Nameplate capacity
• Upfront costs
• Cross-bank shading
• Energy/revenue stream
Economic Drivers:
• Space constraints
• Interconnect Agreement
• Site weather
• Project latitude

11. We optimized a reference designs conductors
against a variety of parameters
Modules per string
Combiner box size
Source circuit
conductor
Combiner box layout
Wiring
direction
Home run
conductor

12. Optimizing the DC subsystem can reduce costs
by 27%
Total electrical costs were calculated
• Wire quantity and cost
• Combiner box quantity and cost
• Electricity value lost from wire resistance
Performance
Driver
Minimum Maximum
Modules per
string
10 15
Source circuit
conductors
#12 AWG #8 AWG
Wiring direction Along racking
Up & down
racking
Combiner box
size
12 strings 24 string
Home run
conductors
0/1 AWG 4/0 AWG
Combiner box
layout
Scattered
throughout
array
Grouped at
inverter
1.7
2.4
0.4
1.0
0.5
0.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Modules
per string
Source
circuit
conductor
Wire
direction
Combiner
size
Home run
conductor
Combiner
layout
Impact on System Costs (¢/Wp)

13. Designing into shade often increases system
size with minimal performance impacts
800
900
1,000
1,100
1,200
1,300
1,400
1,500
800 850 900 950 1,000
EnergyYieldofEachSegmentofModules(kWh/kWp)
System Size (kW)
With MLPE
Standard Mismatch
Baseline:
Zero shade
tolerance
Shade
allowed in
December
Shade
allowed in
Nov-Dec
Shade
allowed in
Oct-Nov-Dec
Shade allowed
year-round
Shade allowed
year-round

14. ($250)
($200)
($150)
($100)
($50)
$0
$50
$100
$150
$200
Year0
Year1
Year2
Year3
Year4
Year5
Year6
Year7
Year8
Year9
Year10
Year11
Year12
Year13
Year14
Year15
Year16
Year17
Year18
Year19
Year20
Year21
Year22
Year23
Year24
Year25
Thousands
What are the catches?
• Need Financial Model
– LCOE, IRR needed to
truly optimize
– Component costs, Rate
database
– How complex is good
enough?
• ‘Manual’ optimization
– Why can’t the computer
do the work?
– Limits scope
– How holistic should the
optimization be? ($650)
($600)

15. DOE Sunshot Award to extend HelioScope with
Design Optimization features
• Started 1Q2014
• Augments HelioScope with optimization features
– Automated optimization
– Financial modelCustomer feedback: staged
optimizations are ideal
– At start of project, goal is maximize energy or revenue
– As project progresses, several deep dives (e.g. wiring)

16. Optimizations will have objective functions that
are optimized under key constraints
• Module Tilt
• Row Spacing
• Positive & Negative
Space
• Interconnect Shading
Requirements (10 – 2)
• Maximum Grid Power
• Target ILR Range
• Project IRR
• Total Revenue/Energy
• LCOE
Independent
Variables
Constraints
Objective
Functions
Ground Coverage Ratio Optimization
Tilt
Annual
KWh
Tilt Sensitivity
15º (optimal)
Annual
KWh
Spacing Sensitivity
2,3m (optimal)
Row-to-Spacing

17. Under the DOE Sunshot program we will
implement staged optimizations
Module Layout DC Subsystem AC Subsystem
• Tilt/GCR
• Azimuth vs TOU
• Fixed vs Trackers
• Shade Setbacks
• String Length
• Inverter Load Ratio
• Conductor Selection
• Conductor Routing
• Component
Selection
• Conductor Selection
• Transformers

18. Thanks!
Paul Gibbs
Founder, Folsom Labs
paul.gibbs@folsomlabs.com
Folsom Labs
www.folsomlabs.com
San Francisco, CA