The Greening of the Rooftop

Module 8

Green Roofing:Clean Energy Roofs

• Photo-Voltaic

• Daylighting

• Wind

Clean Energy Roofs

Clean Energy Roof Options

Clean Energy Roofs

Photo-Voltaic (PV) Roofs

Target StoreStockton, CA

ShiseidoWindsor, NJ

PV Roofs

Clean Energy Generation

PV Roofs

Components

• PV Modules• Balance of System (BOS)• Services

PV Roofs

PV Modules

Monocrystalline Polycrystalline Amorphous

PV Roofs

PV Modules

Technology

Monocrystalline

Polycrystalline

Amorphous

Industry Goal

Efficiency

15-18%

13-15%

5-8%

25%

Notes:

Highest market share, highest cost

Lower cost, gaining in efficiency

Lower cost, leading thin film candidate

Where PV manufacturers want to be by 2015

Source: http://www.pvresources.com

PV Roofs

Balance of System (B.O.S.)

• Key Components– Mounting Systems

– Wiring & Connectors

– Controllers (Energy Management)

– Inverters (DC to AC)

– Batteries (Reserve Energy)

– Load Connection (Building / Grid)

• Account for over 30% of total PV material costs

PV Roofs

Services

• Key Components– Design (Electrical, Structural, Architectural)

– Financing (Power Purchase Agreements, Underwriting)

– Legal (Special Entities, Operating Contracts)

– Installation (Roofing, PV System, Electrical)

– Operation (Monitoring, Power Billing, Incentive Management)

– Maintenance (Inspection, Repair)

• Account for over 30% of total PV installed costs

• Typically provided by a System Integrator

PV Roofs

Residential / Commercial Systems

• Residential Systems– From 1.5 KW to 6 KW total output

– From $15,000 to $60,000 installed cost

– Frequently not tied directly to the grid

– Usually purchased and financed by the homeowner

• Commercial Systems– From 0.5 MW to 2 MW total output

– From $3.25 MM to $12 MM installed cost

– Frequently tied directly to the grid

– Frequently purchased and financed by a “Special Purpose Entity” using a “Power Purchase Agreement”

PV Roofs

Typical Residential PV System(w/o Net Metering)

20 Amp. Controller

8 X 60 Wp Modules

6 X 12v 100Ah Batteries

1500 W Inverter

SeparateDistributionPanel

100 A. Fuse

Loads

Module Array

Combiner Box

DC Disconnect Inverter

DC AC

Meter

AC Disconnect

Main Panel

PV Roofs

Typical Commercial PV System( w/ Net Metering)

Combiner Box

Combiner Box

Module Array

Module Array

Controller

To Grid

PV Roofs

PV Roof System Types

• Non-Integrated

– Mounted on framing over roof

– Similar to other roof-mounted equipment

• Integrated

– Physically incorporated into the roof system

– Performing some roofing function along with power generation

PV Roofs

Non-Integrated PV Roof Systems

Benefits:• Can be tilted to align with

sun’s angle

• Wiring can be placed above roof for easy access

• Long performance track record with conventional silicon modules

Limitations:• Anchorage may require extensive penetration of

roof

• Wind uplift resistance may be a concern

• May be difficult to maintain and service the underlying roof

PV Roofs

Integrated PV Roof Systems

Thin-Film Laminated to Single-Ply

Self-Ballasting and Insulating Solar Paver Thin-Film

Laminated to Standing Seam

Metal

Thin-Film Solar Shingles

PV Roofs

Integrated PV Roof Systems

Benefits:• Reduced material costs for

framing

• Reduced labor costs

Limitations:• Typically restricted to angle of roof – may

compromise output

• Wiring may penetrate the roof membrane

• Roof traffic may damage panels

• Heat build-up may damage underlying roof membrane

• The thin films frequently used in integrated PV have a relatively short performance record compared to conventional solar modules

PV Roofs

What are the Economics?

• PV manufacturing costs are moving down, especially thin-film

• Central power costs are increasing, especially peak demand energy

• Financial incentives for PV are increasing at all levels of government

Currently, PV roofing is not economical across the United States, but…

PV Roofs

What are the Economics?

• The Supply Chain

• The Operating Chain

• The Financial Incentives

To understand PV economics, it is necessary to look at ….

PV Module Manufacturer

Silicon Wafer Manufacturer

System Integrator

Inverter Manufacturer

Connector Manufacturer

Mounting Manufacturer

Control Manufacturer

Battery Manufacturer

System Installer

PV Roofs

Supply Chain

Project Financier $

COMPLETED PROJECT

Investors

Host

Building OwnerBuilding OperatorUtility

System Integrator

Service Contractor

PV Roofs

Operating Chain

$

COMPLETED PROJECT

InvestorsDepreciationOperating NetTax CreditsRebates

Host$Power Purchase

Government, Utility

$Tax CreditsRebates

$Operating Exp.

ServiceRepair

• Federal Incentives (Energy Policy Act of 2005, extended 2008)

– 30% Investment Tax Credit

– 5-Year Accelerated Depreciation

– Additional Tax Deductions if Combined with Energy Efficiency Improvements

• State & Local Incentives (Vary Widely)

– Government & Utility Rebates

– Tax Credits

– Fee Reductions / Exemptions

– Loans

– Grants

PV Roofs

Financial Incentives

See Module 10 for Additional Information

PV Cost Example: Typical Commercial Installation: California

Assumes typical rack-mounted 1 MW rack-mounted installation in California.

1MW Installation: Las Angeles, CA

Revenue First Five Years Twenty Years Energy Savings $1,400,000 $5,600,000 State Incentives $1,600,000 $1,600,000Total Revenue $3,000,000 $7,200,000

Expenses Maintenance ($200,000) ($800,000)

Net Income Less PV Capital Cost ($6,000,000) ($6,000,000) Plus Depreciation (2) $5,200,000 $5,200,000 Plus Federal ITC (3) $1,800,000 $1,800,000

Total Free Cash Flow $3,800,000 $7,400,000ARR 12.3% 5.4%1. $0.22 / KWH first five years

2. Accelerated depreciation per 2005 Energy Policy Act

3. 30% ITC per 2005 Energy Policy Act

PV Cost Example: Typical Residential Installation: Arizona

Source: American Solar Electric (www.americanpv.com)

8 KW Installation: Phoenix, AZ

Installed Cost 55,000$ Less AZ Utility Rebate $ Less AZ ITC (1,000)$ Less Federal ITC (16,500)$ Net System Cost 13,500$

Ave. Annual Production 14,000 kWh

Ave. Annual Energy Savings 1,820$

20-Year Energy Savings (Constant $) 36,400$

20-Year ARR 13.5%

(24,000)

Benefits: Current Limitations:• Clean energy generated

• Peak energy demands reduced

• Many states & local utilities offer incentives

• Federal incentives in place until 2016

PV Roofs

Overall Benefits & Limitations

• Significant incentives required to achieve “grid parity”

• Financing may be complicated

• Maintenance: Increasing roof traffic. Leak detection may be difficult

• Durability: Underlying roof system must be designed to meet or exceed PV system service life.

• Design & Commissioning: How is system performance validated?

• Accountability: Who will be accountable for the integrated system?

Clean Energy Roofs

Daylighting

West Valley LibrarySan Jose, CA

• Passive Systems

• Active Systems

• Hybrid Systems

Clean Energy Roofs

Daylighting

Daylighting

Passive Systems

Passive Systems Capture, Reflect &

Direct Daylight

Active Systems

Follow the Sun to

MaximizeSunlight Capture

Daylighting

Active Systems

Daylighting

Hybrid Systems

Hybrid Systems Combine Solar and Electric

Lighting in an Integrated

Package

Benefits: Current Limitations:• High return on investment

• Excellent product to integrate into a roof replacement

• Many states and utilities have incentive programs

• Can be used as part of an energy savings plan to meet the Federal Commercial Energy Efficiency Tax Deduction

Daylighting

Benefits & Limitations

• Design is complex: Must consider heat loss / heat gain along with lighting savings

• Commissioning: How is system performance validated?

• Durability of newer active systems – little long-term performance data

• Accountability for hybrid systems: Who will be accountable for the integrated system?

Clean Energy Roofs

Wind

Mercy Lakefront SROChicago, IL

Staples Distribution CenterMonrovia, CA

Adventure AquariumCamden, NJ

Roof Wind Systems

Vertical Turbines

Single Vertical Turbine

Multiple Vertical Turbine

Roof Wind Systems

Horizontal Turbines

Single Horizontal Turbine

Multiple Horizontal Turbines

Ganged Horizontal Turbines

Roof Wind Systems

Benefits & Limitations

Benefits: Current Limitations:• Higher return on

investment than PV

• New multiple arrays can generate significant power

• Easily integrated into rooftop PV systems

• Many states and utilities have incentive programs

• Relatively low total power capability

• May produce vibrations that may adversely affect roofing system

• Design & commissioning: How is system performance validated?

• Durability of newer multiple systems – little long-term performance data

• Who will be accountable for the integrated system?

• Interstate Renewable Energy Council

• U.S. Department of Energy Solar Energies Technology Program

• Whole Building Design Guide: Building-Integrated Photovoltaics (BIPV)

• Daylighting Collaborative

Clean Energy Roofs

Find Out More…

http://www.irecusa.org/

http://www1.eere.energy.gov/solar/

http://www.wbdg.org/resources/bipv.php

http://www.daylighting.org

WBDGWHOLE BUILDING DESIGN GUIDE