Optimizing PV Designs with HelioScope

Sandia Performance Modeling Workshop

Paul Gibbs May 5, 2014

paul.gibbs@folsomlabs.com

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

HelioScope is a design-driven PV modeling tool

Principles

• Design-driven

• Component-level

• Cloud-based

Values

• Throughput Velocity

• Value Engineering

HelioScope Tour: Adding a Field Segment

HelioScope Tour: Modifying an Array

HelioScope Tour: Generating Wiring

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

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

We designed our interface specifically to

encourage value-engineering

Designs

Conditions

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

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

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

Modulesper string

Sourcecircuit

conductor

Wiredirection

Combinersize

Home runconductor

Combinerlayout

Impact on System Costs (¢/Wp)

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

Ene

rgy

Yie

ld o

f Ea

ch S

egm

en

t o

f M

od

ule

s (k

Wh

/kW

p)

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

($250)

($200)

($150)

($100)

($50)

$0

$50

$100

$150

$200

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ear

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ear

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ear

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ear

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ear

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ear

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ear

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ear

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ear

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Th

ou

san

ds

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)

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)

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

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

Thanks!

Paul Gibbs

Founder, Folsom Labs

paul.gibbs@folsomlabs.com

Folsom Labs www.folsomlabs.com

San Francisco, CA