metal roofing and solar

A durable integrated systemA durable integrated systemfor PV installations on existing and new roofsfor PV installations on existing and new roofs

Presentation ContentBasics of metal roofing

Basics of photovoltaics (PV)

Synergy of solar and metal roofing

The most cost-compelling choice

Retrofitting opportunities

Look at the roof and PV system together as a single asset.

Then assess the total cost of ownership over the total life of the asset

Basics of Metal Roofing

Metal Roof BenefitsSustainable

Reflective, emissive

More energy efficient

LEED® friendly

Made from recycled materials

100% recyclable

Aesthetically beautiful

Metal is Durable

1200-1450

Metal OffersDesign Flexibility

Metal ProvidesLong Service Life

Coatings for SteelGalvanized Zinc

Aluminized™ Aluminum

Galvalume® Aluminum + Zinc

Metal is Sustainable

SustainabilityStrength, durability, longevity• Resists harsh weather, wind, and fire with minimal or no

maintenance• Impervious to UV degradation• Galvalume® steel standing-seam roof has 40- to 60-year

service life, depending upon environmental severity

25% recycled content, 100% recyclable • At a 93.3% recycle rate, steel is the most highly recycled

construction material available.*

Energy efficiency• Meets ENERGY STAR requirements with high reflectance

Lower life-cycle cost than other roof types*Source: Steel Recycling Institute, 2008

35-year-old Galvalume® steel roofNew Orleans, LA

28-year-old roof Ergoldsbach, GermanyThis roof, which is about to be retrofittedwith a PV array, is estimated to have a remaining service life of 30 years or more.

Metal Roof Benefits

Features• Sustainable• Reflective, emissive• More energy efficient• LEED® friendly• Made from recycled

materials• 100% recyclable• Aesthetically beautiful

Environmental Benefits• Reduce landfill waste• Reduce carbon footprint• Accommodate solar

technologies• Retain properties• Reduce roof maintenance• Provide long service life

Basics of Photovoltaics

Solar Power SystemsSystem types• thin film

- amorphous silicon (a-Si)- cadmium telluride (CdTe)- copper indium selenide (CIS)- copper indium/

gallium diselenide (CIGS)- light-absorbing dyes- dye-sensitized solar cells (DSSC)

Solar Power SystemsSystem typesmono- and poly-crystallineMetal roofs accommodate necessary attachment hardware.Eligible for Federal solar-energy tax creditsOther benefits beyond solar energy

Issues: PV Attachment to Conventional RoofRequires waterproofingat solar array attachmentsRequires dismantling• Remove old• Install new• Reinstall PV

No holes!

PV Attachment to Metal Roof

Metal Roof with PVNo holes = no leaks• Thin-film and crystalline systems

No costly reinstallationLonger service life• 24%–43% savings over installing PV over conventional roofs

Considerations for PV over conventional roofs must include long-term roof-replacement cost

Thin Film Laminated PVThin-film amorphous silicon thickness =less than 1 micron

Stainless steels substrate = 5 mil

Protective coating = ETFE film

Average weight = .7 lbs/sq ft

Thin-film PV is flexible, durable, and fits into standing seam roofs

Thin-film applications are aesthetically pleasing, casting no shadows or causing any glare.

Crystalline Si PV Panels

Popular for vast expanses of commercial, industrial, office, and retail rooftops (±700,000,000 sf annually)

Top Solar StatesCumulative as of EOY 2008

0 100 200 300 400 500 600

North Carolina

Oregon

Connecticut

Hawaii

New York

Arizona

Nevada

Colorado

New Jersey

California

Source: IREC

Prices are coming DOWN!Average wholesale and factory gate pricing (2009)

$0.00

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

$4.00

Jan Feb Mar Apr May Jun Jul Aug Sep

WholesaleFactory Gate

What is the service life of PV?

The warranted life = 25 years…but the service life ≈ 30 years.

Penetration of Conventional Roof System

Options for mountingto conventional roof types:

Option• Penetrations

• Ballast

• Adhesion

• Aerodynamic• Unique Collectors

Problem• Cost• Risk of leakage• Warranty violations• Limited to new

construction• Added to dead load• Limited to new or reroof• Limited to thin-film

alternatives• Cost• Cost

More than 10,000 points of attachment

Conventional Roof TypeRacking components .65Anchorage/waterproofing .20System assembly (labor) .20

Mounting system cost 1.05

Total system cost 5.50Total system cost 6.40

Mounting Cost Summary(dollars per Watt)

Standing Seam Metal RoofSeam clamps and interface .10System assembly (labor) .10

Mounting system cost .20

Total system cost 4.65Total system cost 5.55

13% of SYSTEM COST13% of SYSTEM COST15.5% of SYSTEM COST15.5% of SYSTEM COST

Source: www.energycodes.gov

Map of DOE Proposed Climate ZonesAdopted by ASHRAE and IECC

AGED BRONZE COLORED ROOF:

T Sun = 174º FT Shade = 118º FΔT Sun to Shade = 56º F

(ambient = 81º F)

A convective air plenum ensures even A convective air plenum ensures even cooler temperatures.cooler temperatures.

Conventional Roof Types: Service LifeService life of PV = 30 years ±

Service life of BUR = 19.8 years

Service life of APP = 16.1 years

Service life of SBS = 17.7 years

(The service life of other commercial roof types = 12–20 years.)

Source: Carl Cash Survey, Simpson, Gumpertz & Heger, 2005

Conventional Roof Types: Service LifeService life of PV = 30 years ±

Service life of BUR = 19.8 years

Service life of APP = 16.1 years

Service life of SBS = 17.7 years

(The service life of other commercial roof types = 12–20 years.)

Source: Carl Cash Survey, Simpson, Gumpertz & Heger, 2005

Roof Service Life

Roof Service Life

DEFICITDEFICIT

= 10-18 years

= 10-18 years

So when roof life expires…So when roof life expires…dismantle the PV array…dismantle the PV array…tear the roof off…tear the roof off…

throw it away…throw it away…reroof, and then…reroof, and then…reassemble the PV array.reassemble the PV array.

SSMR: Service LifeService life of PV = 30 years

Service life of SSMR = 50 years

No roof replacement—the roof outlives the PV system!

SSMR: Service LifeService life of PV = 30 years

Service life of SSMR = 50 years

No roof replacement—the roof outlives the PV system!

Roof Service Life

Roof Service Life

SURPLUS

SURPLUS

= 10–18 years

= 10–18 years

Coated Steel SSMRInitial cost of roof $ 7Initial cost of PV $56Initial cost Subtotal $63

Total 30-year cost $63(20-year roof life surplus)

Economic Impact of Roof Replacement (assuming new construction)

15-Year TPO Single-PlyInitial cost of roof $ 4Initial cost of PV $64Initial cost Subtotal $68Yr 15 PV removal $ 4Yr 15 Roof Recover $ 3Yr 15 PV re-assy $ 9Total 30-year cost $84

(0 roof life)

Coated Steel SSMRInitial cost of roof $ 7Initial cost of PV $56Initial cost Subtotal $63

Total 30-year cost $63(20-year roof life surplus)

Economic Impact of Roof Replacement (assuming new construction)

15-Year TPO Single-PlyInitial cost of roof $ 4Initial cost of PV $64Initial cost Subtotal $68Yr 15 PV removal $ 4Yr 15 Roof Recover $ 3Yr 15 PV re-assy $ 9Total 30-year cost $84

(0 roof life)A savings of 25%

A savings of 25%

over the life

of the system.

over the life

of the system.

Method: Direct Mount—seam clamp and interfaceMethod: Direct Mount—seam clamp and interfaceMounting system cost: $0.087/wattMounting system cost: $0.087/watt

Look at the roof and PV system together as a single asset.

Then assess the total cost of ownership over the total life of the asset

Retrofit Solutionsfor Existing Buildings

Solutions for any reason or purpose

Solutions for any reason or purpose

BeforeBefore

AfterAfter

Reroofing SolutionsMetal over existing flat roofs• Replace petroleum-based roofing products • Add slope to a flat or nearly flat roof• Enhance aesthetics, curb appeal

Retrofit

Economical for new construction

Flat Roof Applications

After

Before During

Before

Reroofing SolutionsMetal over existing flat roofs• Replace petroleum-based roofing products • Add slope to a flat or nearly flat roof• Enhance aesthetics, curb appeal

Metal over existing sloped roofs • Replace petroleum-based roofing products• Upgrade wind-uplift and energy requirements• Restore aged metal roofs

Sloped Roof Solutions

Reroofing SolutionsMetal over existing flat roofs• Replace petroleum-based roofing products • Add slope to a flat or nearly flat roof• Enhance aesthetics, curb appeal

Metal over existing sloped roofs • Replace petroleum-based roofing products• Upgrade wind-uplift and energy requirements• Restore aged metal roofs

Metal can alter roof geometry to improve drainage issues and reorient slope for optimal solar gain

Problematic RoofsDuring Near Complete

During After

Energy-Saving OpportunitiesSignificant savings, minimal investment

Energy savings from• adding insulation

Insulated Applications

Existing roofand purlins

New metal roof

New subpurlins

New insulation

Energy-Saving OpportunitiesSignificant savings, minimal investment

Energy savings from• adding insulation• radiant barrier

installation• convective ventilation

Less30%–45% heat gain

Natural Convective Ventilation (ASV)New metal roof

Existing roof

Hot air out

Ambient air in

Air heats upand moves upward

by convection

Radiant heat Less heat loss

Building heat

Energy-Saving OpportunitiesSignificant savings, minimal investment

Energy savings from• adding insulation• radiant barrier

installation• convective ventilation• renewable solar

- thermal heat recovery- solar water heating

Solar Thermal Heat Recovery

Ambient air inHeated air distributed to HVAC system with

solar powered fan

Air heats upand moves upward

by convection

New metal roof

Existing roof

Winter –closed ridge

Solar Thermal Water Heating

New metal roofOptional insulation

Vented eave

Circulated fluidin flexible tubing heats up

Reflective radiant barrier and insulation

Retrofit Makes $enseEnergy Saving Solutions

SummaryThe ideal platform for PV installation

A sustainable product

A strong synergy between PV and metal roofing

Significant cost savings possible over life of metal roof

Retrofit opportunities allow for PV benefits on existing buildings