solar energy seminar summit county builders association

Solar Energy Seminar

Summit County Builders

Association

2

AgendaContext: fossil fuels cost, availability, and environmental issuesSolar Resource: geometry of the sun's path, Breckenridge/Frisco weather data.Passive Solar Heating and Cooling Load AvoidanceDaylightingNatural VentilationSolar Water Heating and Solar Space HeatingSolar Ventilation Air HeatingPhotovoltaicsFinancial Incentives: Federal and Utility rebates and tax credits

3

Colorado Energy Use

1,351,463 billion BtuTotal Colorado

4.8 millionPopulation

297 million BtuPer Capita

http://tonto.eia.doe.gov/state/state_energy_profiles.cfm?sid=CO

4

Colorado Energy Use (billion btu)

317,421

289,677

368,433

375,929

ResidentialCommercialIndustrialTransportation

6

Fossil Fuel Resources and Reserves

Total Resource Base

Undiscovered Resources

Uneconomical Resources

Not ProvedReserves

Discovered Resources

Economical Resources .

ProvedReserves

NP

P -

CPNot Producing, Producing, Cumulative Production to date

Proved Undeveloped, Proved Developed

7

Fossil Fuels Exhaustion Time

te = ln{Eres ln(1+I)/E1 + 1}/ln(1+I)Eres= amount of resourceE1= first year extraction rateI= rate of increase in consumption

Natural Gas, E1= 440 million cubic feet/year, I=2%

Colorado Proved Reserves 16596 million cubic feet, te = 28.2 years

Coal, E1 = 1.67 million tons/year, I = 2%Colorado Proved Reserves 382 million tons, te = 86.3 years


8

Abundance of cheap fossil fuels is not a blessing, it is a problem.

9

0

2

4

6

8

10

12

Residential Gas Commercial Gas

Residential Gas 6.14 8.37 5.62 6.61 8.47 10.29

Commercial Gas 5.37 7.71 4.82 5.93 7.48 9.39

2000 2001 2002 2003 2004 2005

Colorado Natural Gas Prices

$/ t

hous

and

cubi

c fe

et


10

Colorado Electric Rates

0

2

4

6

8

10

12

2005 2006

Residential Electricity Commercial Electric

Residential Electricity 8.64 9.76

Commercial Electric 6.99 8.57

Nov-05 Nov-06

c/kW

h


11

The Future of Energy

18801860

500

0

1000

1500

1900 1920 1940 1960 1980 2000 2020 2040 2060

Surprise

Geothermal

Solar

Biomass

Wind

NuclearHydroGas

Oil &NGL

CoalTrad. Bio.

Exaj

oule

s

Source: Shell, The Evolution of the World’s Energy Systems, 1995

12

Renewable Energy Pathways

Wind Energy

Solar Photovoltaics

Solar Thermal Electric

Solar Buildings

Biomass Electric

Biomass Transportation Fuels

Geothermal Energy

Hydropower

Source: Technology Opportunities to Reduce U.S. Greenhouse Gas Emissions, Oct 1997

13

Renewable Energy Cost Trends

100

80

60

40

20

Cos

t of e

lect

ricity

(¢/k

Wh)

0

1980 1985 1990 1995

Photovoltaics4

3

2

1

0Cos

t of e

than

ol ($

/gal

)1980 1985 1990 1995

Bioethanol40

30

20

10

0Cos

t of e

lect

ricity

(¢/k

Wh)

1980 1985 1990 1995

Wind

Cos

t of e

lect

ricity

(¢/k

Wh) 10

8

6

4

2

0

1980 1985 1990 1995

Geothermal

10

30

40

20

Cos

t of e

lect

ricity

(¢/k

Wh)

01980 1985 1990 1995

Solar Thermal

0

5

10

15

20

Biomass Power

Cos

t of e

lect

ricity

(¢/k

Wh)

1980 1985 1990 1995

Source: Billman, Advances in Solar Energy submission, 1/8/99

14

25.7

16.8

3 2.1 1.6 1.4 1.2 0.60

5

10

15

20

25

30

Source: REPP,Worldwatch 1998/99

Nuclear

WindSolar PV

GeothermalNat. GasHydroOilCoal

Global Growth by Energy Source, Annual Average, 1990-98

Fastest Growing Energy Source in the World

15

World PV Cell/Module Production

050

100150200250300350400

Rest of World 3 4 4.7 5 4.6 4.4 5.6 6.35 9.75 9.4 18.7 20.5 23.42 32.6

Europe 6.7 7.9 10.2 13.4 16.4 16.55 21.7 20.1 18.8 30.4 33.5 40 60.66 86.38

Japan 12.8 14.2 16.8 19.9 18.8 16.7 16.5 16.4 21.2 35 49 80 128.6 171.22

United States 11.1 14.1 14.8 17.1 18.1 22.44 25.64 34.75 38.85 51 53.7 60.8 74.97 100.3

Total 33.6 40.2 46.5 55.4 57.9 60.09 69.44 77.6 88.6 125.8 154.9 201.3 287.65 390.5

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

MegaWattts

17

Advantages of Renewable Energy

Cost-effective: least cost alternative in many casesZero emissions on siteEmploys local trades rather than exporting jobs to import energyAvoids fuel delivery and handling risksNo fuel cost fluctuationsEnergy Security: no fuel supply interruptionsReliability: redundant power supplies

18

Renewables go hand-in-hand with Energy Efficiency

Conventional Efficient Integrated efficiency &renewable

Conventional energy use

Renewable energy useQuanity

ofEnergy

19

Building Energy Use

SchoolGrocery Store

OfficeHealth Care

LodgingMercantile

Restaurant

Heating Cooling Ventilation Hot Water Lights Equipment

Building Design

DaylightingLight Shelves

Soluminaire

Durant Middle SchoolNorth Carolina

DaylightingSkylights

• Produces the cost savings

• Provides user more control

• Continuous Dimming– Low voltage control– IC control ballasts ($$)

• Multi-level switching• Produces the cost

savings• Provides user more

control

DaylightingControls

Overhangs

Silver Hill Office Building, Golden COOverhangs on south, none on north.

Building Orientation

• Sun is maximum on the south side in winter, maximum on the roof, east and west in summer.

7

Suntempered Direct Gain

Sunspace Thermal Storage Wall

Principles of Passive Solar HeatingPrinciples of Passive Solar Heating

Direct Gain

NREL Thermal Test Facility

Sunspace

Trombe Wall

NREL Solar Energy Research Facility

Cooling Load Avoidance

Selective Glass

Passive Solar Design Tools

Computer Simulations:

DOE2, EnergyPlus, E-Quest

Energy10

Great Sand Dunes National Monument, CO

1

Solar Ventilation Air Preheating

Transpired Solar Collector

2

Sun warms the surface

4 - 6 in.

Heat conducts from surface to thermal “boundary layer” of air 1 mm thick

Boundary layer is drawn into hole by fan before heat can escape by convectionSouth wallSolar wall

Boundary layer - 1 mm

Transpired Collector Principle

3

Panel Properties

Panels may be aluminum or steelOver 2,600 perforations per m2

Corrugated to increase structural rigidity

4

Typical Installation

Supports create plenumFlashing around edgesInstalled over or around

existing wall openingsInstalled over any non-

combustible wall material

Easy installation – no special skills or tools needed

Solar Ventilation Air Preheating System

6

Typical Connections

Heated air supplied directly into building:Solar-heated air is supplied directly to the building via a perforated flexible ductDucting destratifiesceiling heat reducing heating load Suitable for both new and retrofit applications

7

Typical Connections

HVAC intake preheater:Preheats air before entering air handler, thus reducing load on conventional heaterCan be designed to work in a majority of situations, which makes it ideal for retrofit applications

8

Bypass Damper

9

Winter Operation

10

Summer Operation

Bypass damper brings outside air directly in, bypassing solar wall.

Unheated Air

11

Air Temperature Rise

12

Typical Applications

Preheating ventilation air for:Industrial and maintenance buildings.School and institutional buildings.Apartment buildings.Commercial and penthouse fans.Aircraft hangers.

Crop dryingProcess air heatingCombustion Air pre-heating

13

Industrial

Bombardier’s Canadair Assembly Plant – Ville St-Laurent, QC

14

Commercial

Wasag Building - Switzerland

15

Farming

Piggeries – Eastern Townships, QC

16

Schools

Alaittuq High School – Rankin Inlet, Nunavut

17

Retails

BigHorn Home Improvement Center – Silverthorne, CO

Winner of the 2001 AIA Top 10 Green Projects

Award

18

Military

Fort Carson – Colorado Springs, CO

19

Community Centers

Rapid City Community Center – Rapid City, SD

20

Apartment Buildings

Windsor Housing Authority – Windsor,

ON

21

Residential

Ski Chalet – Ellicottville, NY

22

Crop Drying

Carriere & Sons, California

(Walnut Drying)

23

Collector Sizing

Ac = Vbldg / v wall

Ac = solar collector area (ft 2), might be limited by available wall area.

V bldg = building outside air flow rate (CFM)v wall = per-unit-area airflow through wall

(typically 4 to 8 CFM/ft2. If wall area is sufficient, use the lower value of 4 CFM/ft2).

24

kWh/m2/year

25

Thermal Energy Delivery

Qsolar = A c q useful (#days per week)/7Q saved = Qsolar /η heating

Qsolar = annual heat delivery of solar system (kWh/yr)

η heating = heating system efficiency (typically 70%)

26

Parasitic Fan Power

Q fan = A c q fan (# of hours/year)

q fan = fan energy required to pull air through collector (typically 1 W/ft2)

27

Advantages of Transpired Collectors

Very low cost.Extremely reliable (no moving parts but fan).No maintenance.High Efficiency (up to 80%). Operates near ambient temperature.No problems with freezing or fluid leaks.No storage required.

28

…other benefits

Recovers heat lost through south wall

Ventilation air introduced high in high-bay space• destratifies air

• lower ceiling and exhaust air heat loss.

Positive pressure on building• reduces incoming drafts

• Increases comfort.

Looks better than an old, dilapidated facade

29

Solar Ventilation Preheat System Costs

Installation Costs in Retrofit ApplicationsAbsorber $9.50/ft2

Supports, Flashing, Etc. $2.50/ft2

Installation $4.00/ft2

Other Costs $4.00/ft2

Total $20.00/ft2

30

Natural Gas @ $7.50/Mbtu & 70% eff = $0.032/kWhEnergy

Energy Cost $/kWh

32

Case Study: NREL Chemical Storage

300 ft2

3,000 CFM $6000 cost63% measured efficiencySaves 14,310 kWh/yearSaves $726/year of electric heat (no flames allowed in building)Payback = 8.3 years

33

Case Study: Ford Engine Assembly

20,000 ft2

Savings of 5,811 Mbtu/year Saves $30,000/year

– 17% of plant’s air heating costs

5 year payback period

34

Case Study: GM Battery Plant

4,520 ft2

40,000 CFM Saves 940 Mbtu/year

– Qsolar = 678 Mbtu/yr– Q htrec = 262 Mbtu/yr

Saves $10,200/yearCost $66,530

($14.72/ft2), including duct modifications

Payback period = 6 years

35

Case Study: US Bureau of Reclamation

• Water treatment facility in Leadville, Colorado.

• Estimated savings are more than $4,000 per year

• 7 year simple payback.

36

Case Study: Federal Express Denver, CO

5,000 ft2 (465 m2) system

45,000 cfmsaves 2,300 million

Btu/yearSaves $12,000 per

year lease payments

$4,800/ yearFEDEX saves

$7,200 /year for the 10 year term of the lease.

37

Design Considerations

South-facing is best, but not necessary

+/- 20° of south gives 96-100% of south+/- 45° of south gives 80-100% of south

Black is best, but a wide choice of dark to medium colors may be used with efficiency loss of less than 10%

Windsor Housing Authority, Canada

38

Design Considerations

Black

Classic Bronze

Chocolate Brown

Hartford Green

Medium Bronze

Boysenberry

Rocky Grey

Regal Blue

Forest Green

Hemlock Green

Slate Blue

Redwood

Teal

Slate Grey

Patina Green

Standard Colors

* Actual colors may differ from displayed colors

39

Resources

FEMP Federal Technology Alert http://www.eere.energy.gov/femp/technologies/techdemo_publications.cfm

• RETScreen International Simulation Software www.retscreen.net

• The Database of State Incentives for Renewable Energy (DSIRE) www.dsireusa.org

• Conserval Engineering, Inc www.solarwall.com

• American Solar http://www.americansolar.com/

• InSpire ATAS International Inc. www.atas.com

• National Renewable Energy Lab www.nrel.gov

Photovoltaics

P

Si

B

The Photovoltaic Effect

No material is consumed and the process could continue indefinitely

Phosphorous: 5 valence electrons

Silicon: 4 valence electrons

Boron: 3 valence electrons

P-N

Junction

PV ManufacturingSingle Crystal Multi-Crystal Amorphous Thin

Film

EIA Data, 2004

•13 to 17 % efficiency

•341 MW in 2004


•669 MW in 2004


•47 MW in 2004

050

100150200250300350

Ann

ual

Man

ufa

ctur

(MW

)

BP Sola

r

Kyoce

ra

Shar

pSh

ell

Sany

o

Scho

tt

Mitsub

ishi

Qcells

Source: 2004 World PV Cell/Module Production from Paul Maycock, PV News, March and April issues, 2005.

Largest PV Manufacturers

PV Cell –Cross-sectional View

Antireflection coating

Transparent adhesiveCover glass

p-Type semiconductorn-Type semiconductor Back contact

Hole

Front contact

Current

Electron

Sunlight

PV Cells are wired in series to increase voltage...

and in parallel to increase current

PV Cells

PV is Modular

Cells are assembled into Modules... and modules into arrays.

PV Cells “I-V Curve”

Current (Amps)

Voltage (Volts)

Open Circuit Voltage

Short Circuit Current

Maximum Power Point

Optimal voltage changes with sunlight and temperature

I-V Curve: Sunlight and Current

•Current (Amps) of each cell depends on

•surface area

•intensity of incident sunlight (kW/m2)

IV Curve: Voltage and Temperature

•Voltage (Volts) of each cell depends on

•the material’s band gap (eV),

•goes down slightly with increasing temperature

PV Module Nameplate Rating

• “Rated Power” is the output of a PV module under standard reference conditions – 1 kW/m2 sunlight, – 25 C ambient temperature– 1 m/s wind speed.

ASTM E1036-96, Standard Test Method for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays Using Reference Cells

Module Nameplate

Best Research Solar Cell Efficiencies

026587136

Effic

iency

(%)

Universityof Maine

Boeing

Boeing

Boeing

BoeingARCO

NREL

Boeing

Euro-CIS

200019951990198519801975

NREL/Spectrolab

NRELNREL

JapanEnergy

Spire

No. CarolinaState University

Multijunction ConcentratorsThree-junction (2-terminal, monolithic)Two-junction (2-terminal, monolithic)

Crystalline Si CellsSingle crystalMulticrystallineThin Si

Thin Film TechnologiesCu(In,Ga)Se2CdTeAmorphous Si:H (stabilized)

Emerging PVDye cells Organic cells(various technologies)

Varian

RCA

Solarex

UNSW

UNSW

ARCO

UNSWUNSW

UNSWSpire Stanford

Westing-house

UNSWGeorgia TechGeorgia Tech Sharp

AstroPower

NREL

AstroPower

Spectrolab

NREL

Masushita

Monosolar Kodak

Kodak

AMETEK

Photon Energy

UniversitySo. Florida

NREL

NREL

NRELCu(In,Ga)Se2

14x concentration

NREL

United Solar

United Solar

RCA

RCARCA

RCA RCARCA

Spectrolab

Solarex12

8

4

0

16

20

24

28

32

36

University ofLausanne

University ofLausanne

2005

Kodak UCSBCambridge

NREL

UniversityLinz

Siemens

ECN,The Netherlands

Princeton

UC Berkeley

Efficiency versus Size• Efficiency= power out/power in• Power in = Area (m2) * 1 kW/m2• For Example:

– 1 kW of 15% efficient crystalline71ft2

– 1 kW of 9.5 % efficient amorphous 99ft2

Price of PV Modules

0

5

10

15

20

25

30

35

1975

1980

1986

1990

1992

1994

1996

1998

2000

2002

Year

PV M

odul

e Pr

ice

($/

$3.09

Source: EIA 2005 data

Cost of Photovoltaic Systems

• Small (10kW) Grid Connected: $8,800/kw

• Small Off Grid with Batteries, etc$17, 000/kW

Source: RS Means “Green Building Project Planning and Cost Estimating”

Material Cost ($/kW)

Labor Cost ($/kW)

Equipment Rental Costs ($/kW) Total ($)

PV Modules $5,730 $248 $107 $6,085Roof Preparation $100 $100 0 $200Rack Structure $150 $150 0 $300Array Electrical $300 $248 0 $548Utility Connection $10 $20 0 $30Inverter $590 $80 0 $670Other Elect $500 $200 0 $700AC Disconnect $33 $12 0 $44DC Disconnect $43 $12 0 $55Isolation Transformer $110 $55 0 $165Total $7,566 $1,124 $107 $8,796

Diffusion Model:As the cost of PV comes down, and the cost of alternatives go up, PV applications grow from high-value niche applications to widespread use.

Small, Remote Loads

Hybrid and Village Power Peaking and high value utility connects

Bulk Power

You Are Here

Cost Effective PV Applications

PV Markets

Industrial

Residential

Commercial

Transportation

Utility

Government

Other

• Most Cost Effective:– Small Loads

• Emergency Call Boxes• Irrigation Controls• Sign lighting

– Avoided Line Extensions ($20k to $100k/mile)

• Water Pumping• Residential

– Remote Diesel Generators ($0.19 to $1.68/kWh)

2005 EIA data

Grid Interactive

Remote

Communication

ConsumerGoods

Transportation

World PV Production

0200400600800

10001200140016001800

Rest of World 3 4 4.7 5 4.6 4.4 5.6 6.35 9.75 9.4 18.7 20.5 23.42 32.6 55 83.8 140 290

Europe 6.7 7.9 10.2 13.4 16.4 16.55 21.7 20.1 18.8 30.4 33.5 40 60.66 86.38 135 193.3 314.4 450

Japan 12.8 14.2 16.8 19.9 18.8 16.7 16.5 16.4 21.2 35 49 80 128.6 171.2 251 363.9 602 810

United States 11.1 14.1 14.8 17.1 18.1 22.44 25.64 34.75 38.85 51 53.7 60.8 74.97 100.3 120.6 103 139 180

Total 33.6 40.2 46.5 55.4 57.9 60.09 69.44 77.6 88.6 125.8 154.9 201.3 287.7 390.5 561.8 744.1 1195 1727

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

MW

of P

V

prod

uced

per

yea

r

Sources: 2004 World PV Cell/Module Production from Paul Maycock, PV News, March and April issues, 2005; Energy Information Administration; NREL National Center for Photovoltaics

PV System Components(depending on type of system)

• PV Array to convert sunlight to electricity• Array Support Structure and Enclosure to protect other

equipment• Maximum Power Point Tracker to match load to optimal array

voltage• Batteries to store charge for when it is needed• Charge Controller to protect battery from over-charging• Low Voltage Disconnect to protect battery from over-

discharging• Inverter to convert direct current (DC) to alternating current

(AC)• Wiring, combiner boxes, fuses and disconnects• Automatic generator starter/stopper to start a generator when

battery is too low

Simple Direct Drive PV System

Simple DC PV System with Battery Storage

DC PV System Example:PJKK Federal Building, HI

• 2 solar panels per lamp with peak output of 96 watts

• 39 Watt fluorescent lamps, 2500 lumens

• 90 amp-hour battery powers 12 hours per night

• ~$2500 per light

AC PV System with Inverter

Inverter

Converts Direct Current (DC) to Alternating Current (AC)

Inverter Technology• Various DC and AC voltages, number of phases• MODIFIED SINE WAVE (Trace UX, Trace DR, Powerstar,

Portawattz– low cost, slightly more efficient– Bad for some computers, photocopy machines, laser printers, and

cordless tool rechargers. • TRUE SINE WAVE(Trace SW, Prosine, Exeltech, SMA)

– power of better quality than utility• SIZE from under 100 watts to 10 kW, larger are custom• EFFICIENCY 85 to 95%. • FEATURES: meters, alarms, battery charger, grid interaction,

automatic shut down, start/stop other devices.• UL Standard 1741, Standard for Static Inverters and Charge

Controllers for Use in Photovoltaic Power Systems – incorporates the testing required by IEEE 929 – includes design (type) testing and production testing.

Utility-Connected (Line-Tie) PV System

Utility-Connected PV Example: Presidio Thoreau Center

• Building-Integrated Photovoltaics

• 1.25 kW PV Array• Spacing between cells

admits daylight into entryatrium below

Grid-Connected System

Source: Powerlight

Hybrid PV/Generator System

PV/Propane Hybrid Example: Joshua Tree National Park

• 20.5 kW PV Array

•613 kWh battery bank

•35 kW propane generator

•$273,000 cost financed by Southern California Edison under 15 year tariff

Building-Integrated PV (BIPV)

Roof-integrated photovoltaics

Example: Coronado Island CA 924 kW, cost $7.7 million

Coronado Island CA PV System Performance

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

Jan-04

Feb-04

Mar-04

Apr-03 May-03

Jun-03 Jul-03 Aug-03

Sep-03

Oct-03 Nov-03

Dec-03

Month

Pow

er P

rodu

ctio

n, k

Wh/

mon

th

0

100

200

300

400

500

600

700

800

900

Peak

Pow

er, k

W

829 kW AC maximum delivery

1,228,658 kWh/year delivery

Energy Delivery versus OrientationData for New York City

Annual Energy Production from 1 kW of PV (84 Ft2) on each side

• North 554 kWh/yr• East 871 kWh/yr• South 1097 kWh/yr• West 833 kWh/yr• Horizontal 1393 kWh/yrBy comparison…• Tilt=41 deg 1530 kWh/yr• 2-axis track 1929 kWh/yr

System Efficiency

Array 10% Efficiency

Battery 80% Round-trip Efficiency

Inverter 90% Efficiency

100 Watts from sun > 10 Watts >8 Watts > 7.2 AC Watts to load

Overall system efficiency is product of component efficiencies. Example 0.10*0.80*0.90=0.072...exacerbated by mismatch losses, typical system efficiency = 0.06

Efficiency = power out / power in

PV System Sizing ExerciseStand-Alone Applications

PV System SizePrated = L

Imin

Prated = rated PV power (kW) L = Daily Load on PV = electricity

required/inverter efficiency/battery efficiency (kWh/day)

I min = minimum daily solar radiation (sun hours/day)

if you want to know how big in m2, divide Prated by 100 W/m2

Annual Energy DeliveryEs = L * 365 (days/year)Wasted solar = (Prated Iave - L) * 365 (d/y) I ave = average solar radiation (sun hours/day)

January June December

Month

ener

gy Solar

Load

Wasted Solar

PV System Sizing: Grid/Generator-Connected

Solar System SizePrated = L

ImaxI max = maximum daily solar radiation (sun hours/day)

Annual Electricity GenerationEgen = Prated Iave 365

Annual Fuel SavingsEs = Prated Iave 365

ηgenerator

ηgenerator = auxiliary generator efficiency(typically 9 kWh/gallon for diesel, 6 kWh/gallon for propane)

January June December

Month

ener

gy Load

Solar

Generator

Sizing Example: Small Load in San Francisco• Daily Electric Load

Lights 120 Watts * 4 hours/day = 480 Wh/dayFan 250 Watts * 2 hours/day = 500 Wh/dayClock 20 Watts * 24 hours/day = 480 Wh/dayPeak Load 390 W Total Daily Load = 1.460 kWh/day

• Inverter sizing: at least 390 W, say 500W.

• Battery Sizing: 3 days storage * 1.46 kWh/day = 4.38 kWh4.38 kWh/0.5 max depth of discharge= 8.76 kWh

• Array Sizing• Add system inefficiency to Load

1.46 kWh/day/0.80 battery efficiency/0.90 inverter efficiency = 2.027 kWh/day

• For San Francisco, tilt equal to 37 degrees (local latitude)Imax = 6.8, I ave = 5.4, and I min = 3.4 (kWh/m2/day = sunhours/day)

• If PV stands alone to meet the load, size for minimum sunPrated = L / Imin = 2.027 kWh/day / 3.4 sunhours/day)

= 0.596 kWcould be eight modules seventy-five watts each.

PV Energy Delivery= 2.027 kWh/day * 365 days/year = 740 kWh/year

PV Sizing Example: Small Load in San Francisco

PV Sizing Example: Small Load in San Francisco. What if Grid Connected?

• No Battery

• If PV is backed up by utility or generator, size for maximum sunPrated = L / Imax = 2.027 kWh/day / 6.8 sunhours/day)

= 0.298 kW

PV Energy Delivery = 0.298 kW*5.4 hrs/day*365 days/year = 587 kWh/year(with the rest, 152 kWh, coming from the utility or generator)

Wire Selection

• T Thermoplastic insulation• H 75°C (Note: lack of "H" indicates 60°C)• HH 90°C• N Nylon jacket• W Moisture resistant• R Rubber insulation• U Underground use• USE Underground Service Entrance *• UF Underground Feeder *• SE Service Entrance *• -2 90°C and wet

Type Temp. °C/°F

Moist Condui Req.

Sunlight Res.

THHN 90/194 Damp Yes No THWN 75/167 Wet Yes No THWN 90/194 Dry Yes No THWN-2 90/194 Wet Yes No THW 75/16 Wet Yes No THW-2 90/194 Wet Yes No RHW 75/167 Wet Yes No RHW-2 90/194 Wet Yes No RHH 90/194 Damp Yes No USE 75/167 Wet No Yes USE-2 90/194 Wet No Yes UF 60/140 Wet No Marked SE 75/167 Wet No Yes

Use only 90C (not 60 or 75C) temperature rating

Wire Sizing• Ampacity Requirements (safety): 1.25*1.25* amps• Wire Length for 2% Voltage Drop in 12 V

• Conduit: conductor fills 40% of cross sectional area

Amps #14 #12 #10 #8 #6 #4 #2 #1/0 #2/0 #4/01 45 70 115 180 290 456 720 . . .2 22.5 35 57.5 90 145 228 360 580 720 10604 10 17.5 27.5 45 72.5 114 180 290 360 5806 7.5 12 17.5 30 47.5 75 120 193 243 3808 5.5 8.5 11.5 22.5 35.5 57 90 145 180 290

10 4.5 7 11.5 18 28.5 45.5 72.5 115 145 23015 3 4.5 7 12 19 30 48 76.5 96 15020 2 3.5 5.5 9 14.5 22.5 36 57.5 72.5 11625 1.8 2.8 4.5 7 11.5 18 29 46 58 9230 1.5 2.4 3.5 6 9.5 15 24 38.5 48.5 7740 . . 2.8 4.5 7 11.5 18 29 36 5650 . . 2.3 3.6 5.5 9 14.5 23 29 46100 . . . . 2.9 4.6 7.2 11.5 14.5 23150 . . . . . . 4.8 7.7 9.7 15200 . . . . . . 3.6 5.8 7.3 11

American Society for Testing and Materials (ASTM)

• nearly 100 standards regarding solar energy systems• American Society for Testing and Materials (ASTM)

100 Barr Harbor DriveWest Conshohocken, PA 19428Phone: (610) 832-9585; Fax: (610) 832-9555Email: [email protected] Wide Web: http://www.astm.org/

• Annual Book of ASTM Standards, Volume 12:02: Nuclear, Solar and Geothermal Energy

ASTM E44.09 Standards

• E 927-91 Specification for Solar Simulation for Terrestrial PV Testing • E 948-95 Test Method for Electrical Performance of PV Cells using Reference Cells under Simulated Sunlight • E 973-91 Test Method for Determination of the Spectral Mismatch Parameter Between a PV Device and a PV Reference Cell • E 1021-95 Test Methods for Measuring Spectral Response of PV Cells • E 1036-96 Test Methods Electrical Performance of Nonconcentrator Terrestrial PV Modules and Arrays using Reference Cells • E 1038-93 Test Method for Determining Resistance of PV Modules to Hail by Impact with Propelled Ice Balls • E 1039-94 Test Method for Calibration of Silicon Non-Concentrator PV Primary Reference Cells Under Global Irradiation• E 1040-93 Specification for Physical Characteristics of Non-Concentrator Terrestrial PV Reference Cells • E 1125-94 Test Method for Calibration of Primary Non-Concentrator Terrestrial PV Reference Cells using a Tabular Spectrum • E 1143-94 Test Method for Determining the Linearity of a PV Device Parameter with Respect to a Test Parameter • E 1171-93 Test Method for PV Modules in Cyclic Temperature and Humidity Environments • E 1328-94 Terminology Relating to PV Solar Energy Conversion • E 1362-95 Test Method for the Calibration of Non-Concentrator Terrestrial PV Secondary Reference Cells • E 1462-95 Test Methods for Insulation Integrity and Ground Path Continuity of PV Modules • E 1524-93 Test Methods for Saltwater Immersion and Corrosion Testing of PV Modules for Marine Environments • E 1596-94 Test Methods for Solar Radiation Weathering of PV Modules • E 1597-94 Test Method for Saltwater Pressure Immersion and Temperature Testing of PV Modules for Marine Environments • E 1799-96 Practice for Visual Inspection of PV Modules • E 1802-96 Test Methods for Wet Insulation Integrity Testing of PV Modules

Institute of Electrical and Electronic Engineers (IEEE)

• Standards for electrical and electronic equipment• relates to industry experts.• Institute of Electrical and Electronic Engineers, Inc

345 East 47th Street New York, NY 10017, USA

• P929 Recommended Practice for Utility Interface of Photovoltaic (PV) Systems– display “Utility-Interactive” on the listing label– frequency and voltage limits, power quality, non-

islanding inverter testing

IEEE PV Standards

• 928 IEEE Recommended Criteria for Terrestrial PV Power Systems • 929 IEEE Recommended Practice for Utility Interface of Residential and Intermediate

PV Systems • 937 IEEE Recommended Practice for Installation and Maintenance of Lead-Acid

Batteries for PV Systems • 1013 IEEE Recommended Practice for Sizing Lead-Acid Batteries for PV Systems • 1144 Sizing of Industrial Nickel-Cadmium Batteries for PV Systems • 1145 IEEE Recommended Practice for Installation and Maintenance of Nickel-

Cadmium Batteries for PV Systems • P1262 Recommended Practice for Qualification of PV Modules • P1361 Recommended Practice for Determining Performance Characteristics and

Suitability of Batteries in PV Systems • P1373 Recommended Practice for Field Test Methods and Procedures for Grid-

Connected PV Systems • P1374 Guide for Terrestrial PV Power System Safety

Underwriters Laboratory (UL)

• Standards for Electrical Equipment Safety• relates mainly to manufacturers.• 333 Pfingsten Road Northbrook, IL 60062• UL Standard 1703, Flat-plate Photovoltaic Modules

and Panels• UL Standard 1741, Standard for Static Inverters and

Charge Controllers for Use in Photovoltaic Power Systems – incorporates the testing required by IEEE 929 – includes design (type) testing and production testing.

National Fire Protection Association (NFPA)

• National Electrical Code (NEC)• Electrical Power System Installation• relates to electrical trade and industry experts.• Article 690: Solar Photovoltaic Systems

– requires listing for utility interface inverters• Underwriters Laboratory (UL)• Edison Testing Laboratories (ETL)• Factory Mutual Research (FM)

• Article 230: Disconnect Means• Article 240: Overcurrent Protection• Article 250: Grounding• Article 300 to 384: Wiring Methods• Check out http://www.nmsu.edu/~tdi/codes&.htm

IEC PV Standards

• IEC-891 Procedures for Temperature and Irradiance Corrections to Measured I-V Characteristics of Crystalline Silicon PV Devices

• IEC-904-1 Measurement of PV I-V Characteristics • IEC-904-2 Requirements for Reference Solar Cells • IEC-904-3 Measurement Principles for Terrestrial PV Solar Devices with Reference Spectral Irradiance Data • IEC-904-4 On-Site Measurements of Crystalline Silicon PV Array I-V Characteristics • IEC-904-5 Determination of the Equivalent Cell Temperature (ECT) of PV Devices by the Open-Circuit Voltage Method • IEC-904-6 Requirements for Reference Solar Modules • IEC-904-7 Computation of Spectral Measurement of a PV Device • IEC-904-8 Guidance for Spectral Measurement of a PV Device • IEC-904-9 Solar Simulator Performance Requirements • IEC-1173 Overvoltage Protection for PV Power Generating Systems • IEC-1194 Characteristic Parameters of Stand-Alone PV Systems • IEC-1215 Design and Type Approval of Crystalline Silicon Terrestrial PV Modules • IEC-1277 Guide-General Description of PV Power Generating System • IEC-1701 Salt Mist Corrosion Testing of PV Modules • IEC-1702 Rating of Direct-Coupled PV Pumping Systems • IEC-1721 Susceptibility of a Module to Accidental Impact Damage (Resistance to Impact Test) • IEC-1727 PV-Characteristics of the Utility Interface • IEC-1829 Crystalline Silicon PV Array - On-Site Measurement of I-V Characteristics

Environmental Testing

• ASTM E 1171-93 Test Method for PV Modules in Cyclic Temperature and Humidity Environments

• Temperature -40 to +85 C • Damp heat 85 C, 85%RH• Humidity freeze 85%RH, -40

C • Thermal Shock -40 to

110 C in 20 min

Hail Impact Testing

• ASTM E 1038-93 Test Method for Determining Resistance of PV Modules to Hail by Impact with Propelled Ice Balls

• 1” simulated hailstones• 55 mph• Corner, edge and middle of

module

Cyclic Load Testing

• ASTM E 1830M-96, Standard Test Method for Determining the Mechanical Integrity of Photovoltaic Modules. (30 lb/ft2 cyclic load)

Other Requirements

• Building codes - UBC, SBC, BOCA, local codes• ASTM

– Standard Glass specifications– structural

• Consumer Product Safety Council– Structural Requirements , section 16– tempered, laminated

• Local covenants regarding appearance• National Historic Preservation Act, SHPO

Capabilities:Sunpath GeometrySystem Sizing System ConfigurationOn grid vs. Off grid Est. Power OutputBuilding SimulationsShading Temperature & Thermal Performance Economic AnalysisAvoided EmissionsBuilding Energy Load AnalysisMeteorological Data

Available Software:– PVSYST– MAUI SOLAR

• PV DESIGN PRO– WATSUN PV– PV CAD – PV FORM– BLCC– HOMER– ENERGY-10 – AWNSHADE

PV Design Toolshttp:// www.eren.doe.gov/buildings/tools_directory

58

Requirements for Success• Conservation First • Verify Load Estimates• Appropriate Application• Proven Design• Operational Indicators or Monitoring• Operations and Maintenance Training and Manual• Properly Sized • Require No Manual Intervention• Performance Guarantee

The Solar Resource

Solar Spectrum

• 6% ultraviolet, 48% visible, and 46% infrared light• annual average radiation 1,366 W/m2 in space, • typically less than 1000 W/m2 on Earth.

Declination, d

Winter Solstice,

South

d= -23.45 degSpring Equinox,

d= 0

Fall Equinox,

d=0

Summer Solstice,

d=23.45 degrees North

Sun

Varies like a sine wave throughout the year d=23.45*(SIN(360/365*(284+day of year)))

•Depends on the season

Hour angle, h

-90 deg0 deg+90 degHour angle, h6 pm12 noon 6 amSolar Time

•Depends on time of day

•Earth rotates 360 deg in 24 hours, or 15 degrees per hour

•Hour angle, h=(15 degrees/hour)*(hours from noon)

Position of the Sun

• Altitude angle, a, angle fom the horizon up to the sunsin a=cos l cos d cos h + sin l sin d

• Azimuth angle, z, horizontal from due south to the sun,sin z = sin h cos d/ cos a

• l=latitude (deg), h=hour angle (deg), d=declination (deg)

Sun Position Example

• 10:00 am June 9 in Denver CO• Solar Time 9:00 am

– Daylight Savings Time (one hour earlier)– Distance from Standard Meridian (105-105 deg west, neglect)– Equation of Time (0.02 hours, neglect)

• Declination, d = 23 deg• Hour Angle, h = 45 deg• Latitude, L = 40 deg• Altitude, a = 49 degrees• Azimuth, z = 79 degrees

N. Cheyenne Capitol

Shading

Winter sun

Altitude, a, at h=30, d=-23.45Window Shading: Good

Solar Collector Shading: Bad

Exercise: Design overhang for 1 m high row of windows. noontime shade from 5/11 to 8/12

noontime sun from 11/17 to 1/25

Exercise: Sun Position C

• Solar time 12:00 pm November 17 in Denver CO– Declination, d = -19 deg– Hour Angle, h = 0 deg– Latitude, L = 40 deg– Altitude, a = 31 degrees

• Solar time 12:00 pm May 12– Declination, d = +18 deg– Hour Angle, h = 0 deg– Latitude, L = 40 deg– Altitude, a = 68 degrees

Exercise: Design overhang for 1 m high row of windows. noontime shade from 5/11 to 8/12

noontime sun from 11/17 to 1/25

31 degrees

68 degrees1 m

0.321 m

0.534 m

Shading: horizon profileAltitude angle of horizon at each azimuth angle

Solar Pathfinder

“Sun Hours”• “Rated Power” is the output of a PV module under

standard reference conditions (1 kW/m2 light, 25 C, 1 m/s wind speed).

Example: June in Boulder 6.1 kWh/m2/day = 5.1 “sun hours”/day.

A module “rated” at 1 kW would produce 5.1 kWh in that day.

Time of Day

Sunlight (kW/m2)

Time of Day

Sunlight (kW/m2)

Sun Hours

1 kW/m2

=0

1

12 12

1

0

Daily Average (kWh/m2/day)

kWh/m2/day = sun hours/day

Fixed Tilt/TrackingFixed Tilt Facing Equator

tilt=latitudetilt<latitude for summer gaintilt>latitude for winter gain

One Axis Tracking around axis tilted or flat

Two Axis Tracking both azimuth and altitude of sun around two axes

Effect of Orientation• Average daily solar radiation (kWh/m2/day)

0123456789

10

Jan

Feb Mar Apr

May

Ju

n Jul

AugSep Oct Nov Dec

Horizontal 4.6Tilt=Latitude 5.5Vertical 3.81-axis tracking 7.22-axis tracking 7.4

Data for Boulder CO

Breckenridge Weather Data

Month

Average Dry Bulb

Temperature, °F

Average Daily Maximum Dry

Bulb Temperature,

°F

Average Daily

Minimum Dry Bulb

Temperature, °F

Maximum Dry Bulb

Temperature, °F

Minimum Dry Bulb

Temperature, °F

Average Wet Bulb

Temperature, °F

Relative Humidity, %

Average Wind

Speed, MPH

Average Daily

Horizontal Solar

Radiation, Btu/ft²

Heating Degree Days, Base

65.0 °F

Cooling Degree Days, Base

65.0 °F January 14 29.1 -1 42 -35 11.9 78.9 7.7 772 1581 0 February 16 31.8 1.3 50 -21 14.1 81.7 6.2 1022 1358 0 March 22.1 36 9 51 -5 19.7 80.8 5.9 1367 1318 0 April 31.4 44.4 18.3 57 6 27.3 71 8.5 1814 1010 0 May 41.4 55.5 26.5 70 14 36.3 71.9 7.2 2090 746 0 June 50.3 66.5 33.2 75 25 42.6 63.2 6.1 2331 456 0 July 55.8 73.1 38.6 84 33 48.6 68.8 5.3 2174 283 0 August 53.4 70.5 37.4 79 29 46.8 70 6.5 1984 343 0 September 45.9 62.6 30.2 72 22 39.3 66.6 6 1640 558 0 October 36.1 53.1 21.7 67 11 30.9 67.3 4.9 1252 856 0 November 23.8 38.6 10.9 51 -3 21.3 77 4.9 828 1207 0 December 15.8 30.3 2.6 54 -13 13.8 75.3 4.9 663 1505 0 Year 33.8 49.3 19 84 -35 29.4 72.7 6.2 1495 11219 0

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tem

pera

ture

, °F

Average Hourly by Month

0

100

200

300

400

500

600

Btu/

ft²

Temperatures & Solar Radiation Dillon 1 E, Colorado (adj)

Dry BulbWet BulbGlobalBeamDiffuse

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.010

0 10 20 30 40 50 60 70 80

Hum

idity

Rat

io

Temperature, °F

Typical Day Psychrometric Chart Dillon 1 E, Colorado (adj)

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecemberApprox. Comfort Zone

100%

50%

NREL Solar Radiation Data Manualhttp://rredc.nrel.gov/solar/old_data/nsrdb/redbo

ok/atlas/

Solar Water Heating

2

Technology Overview

Low-temperature collectors:– Unglazed mats for water heating.

Mid-temperature collectors:– Glazed and insulated collectors.

High-temperature collectors:– Evacuated tubes.– Focusing collectors.

Solar Water Heaters intercept solar radiation and use it to heat water. Solar thermal collectors can be categorized by the temperature at which they efficiently deliver heat.

Solar Water Heating

• Water heating accounts for 4.5 Quads/year of 37.6 Quads/year total US building energy use.

• Of this, about 1% (0.05 Quads/year) is currently supplied by solar.– 3% of buildings have solar– One third of each building load by

solar

Solar1%

Oil5%

Propane2%

Electric (Primary)

46%

Natural Gas46%

Collector Types

Technology Overview

4

Energy Collected = optical gains -thermal losses

Q useful = τ α I Ac - Uc Ac(Ts-Tamb)

Efficiency = Energy Collected / Incident Solar ηsolar = Quseful / I Ac

= τ α - Uc (Ts-Tamb)/I, (a line of slope Uc and intercept τ α )

I= incident solar radiation (W/m2)τ = transmissivity of cover glassα = absorptivity of absorber plateAc= collector area (m2)Quseful = useful heat from collector (W)Uc= thermal loss coefficient of collector

(W/C)Ts= storage water temperature (C)Tamb= outdoor ambient temperature (C)

I τ αAc

UUccAAcc(T(Tss--TTambamb))

Q usefulI Ac

Collector Efficiency (Rating)

Which collector is best depends on the temperature...

Efficiency = % of solar captured by collector

Solar Rating and Certification Corp.

•an independent nonprofit organization that tests performance and certifies almost every solar heater on the market today.

•Reports efficiency line and annual performance for different climates and temperature uses.

Contact information

Solar Rating and Certification Corporationc/o FSEC, 1679 Clearlake RoadCocoa, FL 32922-5703Voice (321)638-1537Fax (321)638-1010E-mail: [email protected]

US Solar Thermal Shipments

Source: EIA 2003 Data

0

5,000

10,000

15,000

20,000

25,000

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

Year

US S

olar

The

rmal

Shi

pmen

ts (k

sf)

High TempMid TempLow Temp

9

Passive Systems

Integral Collector StorageThermosyphon

System Types

Active SystemsOpen Loop:– Direct– Drain Down

Closed Loop:– Drain Back– Antifreeze

Passive, Integral Collector Storage (ICS) Direct System

Moderate freeze protection (pipes at risk)Minimal hard water tolerance Very low maintenance requirements

Passive, Thermosyphon, Direct System

Auxiliary element can also be in tank above collector, eliminating the auxiliary tank altogether.No freeze protectionMinimal hard water tolerance Low maintenance requirements

Active, Open-loop, Pumped Direct System

No freeze protection Minimal hard water tolerance High maintenance requirements

Active, Closed-loop (antifreeze), Indirect System

Excellent freeze protection Good hard water tolerance High maintenance requirements

Active, Closed-loop, Drainback, Indirect System

Good freeze protection Good hard water tolerance High maintenance requirements

Recirculation Loop

Requires well insulated collector (evacuated tube) Active protection for freezing and overheating

Recirculation loop

to and from boiler

Tempering Valve to Prevent Scalding:Extremely Important for Safety!

17

Low Temperature Example: Barnes Field House, Fort Huachuca, AZ

2,000 square feet of unglazed collectors3,500 square feet indoor poolInstalled cost of $35,000Meets 49% of pool heating loadSaves 835 million Btu/ year of natural gasAnnual savings of $5,400Installed by the Army in June, 1980.

18

Mid Temperature Example: Chickasaw National Recreation Area, OK

Small Comfort Stations– 195 square feet of flat plate

collectors– 500 gallon storage volume– Cost $7,804– Delivers 9,394 kWh/year– Saves $867 / year

Large Comfort Stations– 484 square feet of flat plate

collectors– 1000 gallon storage volume– Cost $16,100– Delivers 18,194 kWh/year– Saves $1,789 / year

62 units installed 1998Active (pumped), Direct systemsAverage cost $4,000 per system80 sf per system$800 per system HECO rebateSavings of 9,700 kWh/year and $822/year per systemSimple Payback 4 years (with rebate)

Mid Temperature Example: USCG Housing, Honolulu HI

USCG Housing, Honolulu HI

Three closed loop systems with evacuated tube collectors, heat exchanger in the preheat tank. Food-grade Propylene Glycol solution for freeze protection.– Bay F 80 gallon preheat tank and 20 ft2 of

collector area. – Bay B 80 gallon preheat and 40 ft2 of

collector area – Bay D 120 gallon preheat tank and 90 ft2

of collector area , measured output averaged 50,000 Btu/day in December, 98.

Total Cost = $26,000, 15 yr payback

High Temperature Example: Building 209, EPA Lab, Edison NJ

High Temperature Example:Social Security Admin. Philadelphia.

• Reheats Recirculation Loop• 360 Evacuated Heat-Pipe

Collector tubes, 54 m2 gross area, 36 m2 net absorber area

• Cost $58,000• Delivery of 143 million

Btu/year estimated• Installed 2004.

23

High Temperature Example: Phoenix Federal Correctional Institution 17,040 square feet of parabolic trough

collectors23,000 gallon storage tankInstalled cost of $650,000Delivered 1,161,803 kWh in 1999 (87.1% of the water heating load).Saved $77,805 in 1999 Utility Costs.Financed, Installed and Operated under Energy Savings Performance Contract with Industrial Solar Technology, Inc.The prison pays IST for energy delivered at a rate equal to 90% of the utility rate (10% guaranteed savings), over 20 years.

Month Energy and Cost Savings

0

100

200

300

400

500

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Tota

l Del

iver

ed H

eat (

mill

ion

Btu

)

19992000200120022003

High Temperature Example: Phoenix Federal Correctional Institution

Simple Evaluation Procedure

Estimate Daily Water Heating LoadDetermine Solar ResourceCalculate Solar System Size– meet load on sunniest day– undersize rather than oversize

Calculate Annual Energy SavingsCalculate Annual Cost SavingsEstimate System CostCalculate Savings-to-Investment Ratio and Simple Payback Period

Solar Water Heating Costs

– Single, small system $155/ft2

– Large central system $40/ft2

– Swimming Pool system $18/ft2

Source: RS Means “Green Building Project Planning and Cost Estimating, FCI Phoenix project

Daily Water Heating Energy LoadL = MC (Thot - T cold)

L = Daily Hot Water Energy Load (kWh/day)

M= mass of water per day (kg/day), 3.785 kg/gallon

C = specific heat of water= 0.001167 kWh/kg°C

Thot= hot water delivery temperature (°C), often 50 ° C = 120 ° F

Tcold = cold water temperature (°C), often 13 ° C = 55 ° F

Typical Hot Water Usage:

Dormitory 13 gal/day/personMotel 15 gal/day/unitHospital 18 gal/day/bedOffice 1 gal/day/personFood Service 2.4 gal/mealResidence 40 gal/day/personSchool 1.8 gal/day/student

28

Solar Energy ResourceCollectors should face south (in northern hemisphere)Tilt Angle=latitude maximizes annual gain (lat+15°for winter, lat-15° for summer)Location I Max I Ave (kWh/m2/day)Anchorage, AK 4.6 3.0Austin, TX 6.3 5.3Boston, MA 5.6 4.6Chicago, IL 5.7 4.4Denver, CO 6.1 5.5Fargo, ND 6.5 4.6Honolulu, HI 6.5 5.5Jacksonville, FL 6.1 4.9Sacramento, CA 7.2 5.5San Diego, CA 6.5 5.7Seattle, WA 5.7 3.7

For COMPLETE data on hundreds of sites, check out www.nrel.gov

Solar Water Heating System Size and DeliverySolar Water System Size

Ac = L . (ηsolar Imax)

Ac = collector area (m2) L = Daily Load (kWh/day)ηsolar= efficiency of solar system

(typically 0.40)I max = maximum daily solar

radiation (kWh/m2/day)

Annual Energy SavingsEs = Ac Iaveηsolar365

ηboiler

I ave = average solar radiation (kWh/m2/day)

ηboiler = auxiliary heater efficiencygas 0.43 to 0.86, assume 0.57electric 0.77 to 0.97, assume 0.88

heat pump assume 2.0propane 0.42 to 0.86, assume 0.57oil 0.51 to 0.66, assume 0.52

Source: GAMA

Solar Water Heating System Cost and SavingsSolar System CostC = csolar Ac

C = Installed Cost of Solar System ($)

csolar = per-unit-area cost of installed solar system ($/m2), typically $400/ m2 for large system $1000/m2 for small systems$750/ m2 might be average

Annual Cost SavingsS = Es Ce

S = annual cost savings ($/year)

Ce = cost of auxiliary energytypically:Electricity $0.084/kWhNatural Gas $0.040/kWhPropane $0.040/kWhOil $0.025/kWh

Source: FTC

Solar Water Heating System Cost EffectivenessSavings-to-Investment RatioSIR = S*pwf / Cproject is cost effective if SIR>1.

pwf = present worth factor for future savings stream, = 17.4 years for 25 year lifetime and 3% real discount rate (specified by NIST).

Simple Payback PeriodSPB = C / S

Example: 4 person residencein Boulder against electricity

M=4person*40gal/person/day*3.785 kg/gal=606 kg/dayL=MC(Thot-Tcold) =606 kg/day*0.001167kWh/kgC*(50C-18C) =22.6 kWh/dayFor Boulder, CO, Imax = 6.1 and I ave = 5.5 kWh/m2/dayAc = L / (ηsolar Imax) = 22.6 kWh/day / (0.4 * 6.1 kWh/m2/day) =9.2 m2Es = Ac Iave ηsolar 365/ ηboiler = 9.2 m2 * 5.5 kWh/m2.day * 0.4 * 365days/year / 0.88 = 8,452 kWh/yearC = csolar Ac = $1000/m2 * 9.2 m2 = $9,200S = Es Ce = 8,452 kWh/year * $0.084/kWh = $710/yearSIR = S*pwf / C = $710/year * 17.4 years / $9,200 = 1.3SO IT IS COST EFFECTIVE!

2001 Top Five Destinations of Thermal Solar Collector Shipments

State Percent of U.S. ShipmentsFlorida 44%California 29%Arizona 4%Nevada 2%Connecticut 1%

36

Cost-Effective Solar Thermal Applications

Low temperature:• Swimming Pools

Mid temperature:• Residential Hot Water• Cafeterias• Laundries• Air Conditioning Reheat

High temperature:• Industrial Processes• Electrical Generation

Water heating loads constant throughout week and year (or more in the summer).High cost of backup energy (electricity, propane, etc.).Sufficient area to site collectors (1 ft2/gal/d).Sunny climate helps, but is not a requirement- solar works in cold climates too.Need on-site “champion”

37

Requirements for SuccessAppropriate Application (Provide a Reasonable Payback)Proven DesignRedundant Freeze ProtectionProperly Sized (undersized, not oversized)Require No Manual InterventionOperational Indicators or Monitoring

Conservation FirstVerify LoadPerformance GuaranteeRequire Operations and Maintenance Manual and TrainingAcceptance Test

38

Solar System Maintenance Options

Energy Savings Performance Contract:– You pay for delivered energy.

Guaranteed Energy Savings Contract:– You don't pay if energy is not delivered.

Service Contract and Warranty:– You pay fixed service costs, whether needed or not.

Facility does maintenance --– Or, historically, facility doesn't do maintenance:

Low priority (always have hot water at the tap).No inventory of parts and little expertise.Utility bill is always paid while efforts to reduce maintenance budgets are ongoing.

,Temp. Sensor Mount

Expansion Tank

Pump Winding

Pump Capacitor

Leaks

Valves

Collector

PC Board

Relay

DC power supply

Temp. Sensor Open

Working Fine

Problems

O&M Survey of 185 Solar Water Heating Systems

40

Solar Water Heating Resources and References

American Society of Heating, Air Conditioning and Refrigeration Engineers, Inc.– ASHRAE 90003 -- Active Solar Heating Design Manual– ASHRAE 90336 -- Guidance for Preparing Active Solar

Heating Systems Operation and Maintenance Manuals– ASHRAE 90346 -- Active Solar Heating Systems Installation

Manual

Solar Rating and Certification Corporation– SRCC-OG-300-91 -- Operating Guidelines and Minimum

Standards for Certifying Solar Water Heating Systems

FEMP Federal Technology Alert “Solar Water Heating” call 1-800-DOE-EREC or www.eree.energy.gov/femp.

Financing

Project Financing Options• Appropriations• Debt (Commercial Bank Loan)• Mortgage, Home Equity Loan• Limited Partnership• Vendor Financing• General Obligation Bond• Lease• Energy Savings Performance Contracts• Utility Programs• Chauffage (end-use purchase)• Grants• Tax Credits

Home Mortgage or Home Equity Loan• Low Interest Rates, Tax Deductible, Long Terms!• May add to appraised value, mil levy and taxes.• Federal National Mortgage Association (Fannie Mae).

– up to $240,000, market interest rates, allow 2% increase in debt-to-income ratio for energy efficient home, secured, 30 year term.

– Residential Energy Efficiency Improvement Loans up to $15,000 (or up to 10% of base loan), below-market interest rates, unsecured, 10 year term.

• Federal Home Mortgage Loan Corp (Freddie Mac).– up to $240,000, market interest rates or variable prime plus 2%, up

to 10% above base loan amount with Energy Efficient Mortgage.• US Dept of Housing and Urban Development (HUD).

– Up to 10% above base loan amount with Energy Efficient Mortgage.• US Dept of Veterans Affairs (VA).

– for veterans. Up to $230,000, Up to 10% above base loan amount with Energy Efficient Mortgage.

Tips to Reduce Interest Rate:

• Consult with Financier regarding early development of DER contract

• Include fixed termination schedule.• Fix Settlement and Acceptance Dates• Fixed Payments Made On Time• Bundle projects• Be ready to act when negotiating• Escrow or hedge? Project in stages. • Protection of leinholder interest: right to cure or take

performance risk (non-recourse financing).• Make your deal more like standard, commercial

securities.

Financing Example: Energy Efficient Mortgage

Dorothy and Jerry Wheeler Home Mortgage

• 960 Watt PV on new home in Tucson

• PV was $12,000 of $280,000 loan

• 30 year term 7.8% interest• Payments $87/month fixed• Utility savings*, Tax

benefits, reliable, silent, no pollution.

• Included in appraisal (resale).

•$16.5/ month with 6.5 kWh/m2/day solar and $0.0868/kWh powerSource: interview Dorothy Wheeler

Limited Partnership• General Partnership.• Limited Partnership.• No guaranteed rate-of-return (depends on project

performance).• Strategic alliances (eg. Gas LDC partners with DG

supplier).

• 7,200 ft2 solar trough system• $160,000 installed cost

financed by limited partners• 15 years of O&M

($1,800/year) included in price• Heat sold to prison at 90% of

cost of natural gas• Investors paid back from

revenue, but $8000 per year minimum

Financing Example: Limited Partnership

Solar Water Heating Jefferson County Jail

Source: Ken May, IST Corp.

Energy Savings Performance Contracts (ESPC)

• Energy Service Company (ESCo) finances measure in exchange for a share of the energy cost savings.

• Risk of project performance often on the ESCo.• Interest rates prime plus 1.25 to 1.5 % depending on

recourse or non-recourse and perceived risk.• For Federal projects, payments cannot exceed savings and

term cannot exceed 25 years. In practice, term is often less than 15 years.

• Examples include several hundred million dollars worth of projects.

Reallocating the Utility Budget

$

• Pay a lower utility bill• Pay the contractor• Achieve cost savings

Utility Utility BillBill



ContractorContractorPaymentPayment

Govt.Govt.ShareShare

Govt. Govt. ShareShare Energy

Cost Savings

Before ESPCContract

During ESPCContract

After ESPC Contract

Financing Example: Energy Savings Performance Contract

Phoenix Federal Correctional InstitutionSolar Water Heating ESPC

Installed cost of $650,000 for 17,040 ft2 solar fieldDelivered 1,161,803 kWh in 1999 Saved $77,805 in 1999 at $0.067/kWh.Prison paid Industrial Solar Tech. $70,025 (10% savings)Term 20 years.

Financing Example: Super ESPCNaval Base Coronado

750kW Parking Lot Photovoltaic SystemShaded parking for 444 vehiclesProvides 3% of peak summer demand

$7.7M installed cost, $3.6M CA. incentives$228k annual savings, 9.9 yr SPB w/incentivesM&V: Option A using PVWatts analysis for savings; electric meter installed to monitor performanceEmissions reduction benefits:

NOx: 11,660 lbs, SOx: 10,480 lbs, CO2: 7430 tons

DER Financing Example: Super ESPCNaval Base Coronado

Utility Financing

• substitute for wire-based revenue– Utility DER services by unregulated energy services

business– Utility arranges third-party, non-recourse financing– "If they don't and rates go up sharply, people are

going to buy their own solar panels and pull the plug on the utilities." ... " David Freeman, SMUD.

• to cut cost and enhance wire-based revenue

Utility Programs• Projects financed through contracts and ordering

agreements.• Utility Incentives.

– Demand Side Management (DSM) Bidding Programs,– DSM Rebates.

• Example: Hawaiian utilities offer $800 rebate for residential solar water heaters.

– See www.dsireusa.org for state incentives• Projects provided through tariffs.

– approved by State Public Utility Commissions.• Projects to supply Green Power Purchases.

– electric power generated from renewable energy resources.– certified by third party.– often sold at premium price.

www.dsireusa.org

Financing Example: Utility Tariff

Joshua Tree National Park PV System

• 20.5 kW PV Array

•$273,000 cost financed by Southern California Edison

•Monthly payments $4,368: 9.94% interest plus O&M

•15 year term

EPAct-05?

• The Energy Policy Act of 2005 (EPAct-05) is an update to the Energy Policy Act of 1992, an energy policy for the United States. Among many other things, the 1724 page law provides new tax incentives for a number of solar and energy efficiency measures. Among them are---

Credits & Deductions

• Tax credits for– Improvements to existing and new homes– Residential and commercial solar photovoltaic and solar hot

water heating systems– Residential fuel cells– Commercial fuel cells and microturbines– Hybrid or lean burn vehicle

• Tax deductions for – Highly efficient commercial buildings– EPAct tax credits and deductions (except vehicles) only good

in 2006 and 2007!

But First…Some Definitions

• A tax deduction is subtracted from income before total tax liability is computed.

• A tax credit is subtracted directly from the total tax liability.

Example:• A credit is 3 or more times more advantageous to the

taxpayer than a deduction. • A tax credit of $1,000 for someone in the 28% tax bracket

is equivalent to a tax deduction of $3,570 .

Existing Homes

• One time maximum tax credit limit of $500• Primary residence• For improvements and equipment placed in

service during 2006-2007• Product to meet 2000 International Energy

Conservation Code criteria

Qualified Energy Efficiency Improvements

• Tax credits of 10% of the cost• Insulation material or system that reduces

heat loss or gain • Windows including skylights ($200 tax

credit limit)• Exterior doors• Metal roofs that meet Energy Star program

requirements

Qualified Energy Property Tax Credit Limits

• $50 for any advanced main air circulating fan– Used in furnace that uses no more than 2% of

the total annual energy use of the furnace• $150 for any qualified natural gas, propane,

or oil furnace or hot water boiler – Water heater with EF or 0.80 or greater – Furnace or hot water boiler with AFUE of 95%

or greater


• $300 for any item of qualified energy property– Electric heat pump water heater with EF of 2.0

or greater – Electric air source heat pumps with HSPF of

9.0 / SEER 13 or greater– Geothermal heat pumps:

• Closed loop products with EER of 16.2 and COP of 3.3 or greater

• Open loop products with EER of 14.1 and COP of 3.3 or greater


– Direct expansion (DX) products with EER of 15 and COP of 3.5 or greater

– Central air conditioner that receives the highest efficiency tier established by the Consortium of Energy Efficiency as of January 1, 2006

• Split systems – 14 SEER/11.4 EER/9.2 HSPF• Single packaged – 14 SEER/11 EER/8 HSPF

New Homes (Site Built)• $2000 tax credit to eligible contractors for

homes that are Certified to:– Use 50% less for annual heating and cooling

energy than IECC 2003 plus supplements– 20% of savings from building envelope

improvements and equipment must meet NAECA minimum efficiency standards

– Home acquired (purchased) in 2006 - 2007

New Manufactured Homes

• $1000 tax credit per home to builder for homes Certified to:– Use 30% less for annual heating and cooling

energy than IECC 2003 plus supplement– 33% of savings from building envelope

improvements or meet EPA Energy Star Labeled homes program

– Conform to Federal Manufactured Home Construction and Safety Standards

Renewable Energy Credits & Rebates

• Solar hot water (no pools) and Photovoltaics– Commercial

• 30% credit of the cost of a system

– Residential • 30% credit of the cost with a

maximum of $2000 per system

Renewable Energy Credits & Rebates

Photovoltaics (Amendment 37)

– Xcel • PV systems up to 10 kW

– $2.00 per DC watt (nameplate) +– Plus ~$2.50 per DC watt for the Renewable Energy Credits (PVWatts

calculated value based on size, azimuth, tilt, type, inverter)– Monthly $0.115/kWh

• PV systems 10 kW to 100 kW– $2.00 per DC watt (nameplate) +– Monthly $0.115/kWh REC payment

– Colorado Springs Utilities • PV systems up to 10 kW for residential and 25 kW for business applications • ~$4 per AC watt (AC watt calculated based on rating, orientation, tilt,

inverter efficiency)• Expected to decrease $0.25 to $0.50 per year

Renewable Energy Example• Commercial PV -- 10 kW system

– Installed cost $100,000– Utility incentive $45,000 max – Federal tax credit $16,500– Net cost $38,500 – 62% savings through rebates

and tax credits!– Plus generate electricity at retail rate due to net

metering

Commercial Energy Efficiency• EPAct 2005 tax deduction: • Up to $1.80 per square foot• 50% less utility costs than ASHRAE 90.1-2001

compliant model • Energy efficient subsystems ($0.60/sf/subsystem)

– Interior lighting– Heating, cooling, and ventilating and hot water– Envelope

• New construction or existing buildings• Building owner or “designer” for public buildings• Equipment placed in service during 2006-2007

(may be extended)• Requires energy modeling to justify the deduction

Utility Programs Commercial Building by Xcel Energy

• Peak demand rebate (new and existing construction)– Cooling

• Cooling towers - $3/ton• Cooling systems- $10 to $50 per ton

» + $3 to $4 per ton greater efficiency

– Premium Efficiency Motors• $10 to $600 per motor

– Variable Frequency Drives on motors • 1 to 200 hp at $30/hp

Utility Programs Commercial BuildingXcel Energy

• Peak demand rebate continued– New construction:

• Lighting - $1.75 to $18 per fixture, depends on type

– Existing building:• Lighting - $5 to $75 per fixture, depends on

type• VAV boxes - $200 per box to convert from

constant volume

Utility Programs Commercial BuildingXcel Energy• Custom Efficiency program

– Any energy efficiency measures not identified in the prior list may be considered for a Custom Efficiency Rebate

– Xcel determines energy savings internally and provides rebate

– Xcel calculations are not based on an hourly simulation, must work with Xcel before purchasing equipment

– Up to $200 per kW of demand saved

Utility Programs Commercial Building Fort Collins Utility

• Peak demand rebate– Greater of $500 per kW or $0.10 per kWh saved – Applicable systems:

• Lighting; Air conditioning; Motors; • Mechanical systems

• Cooling systems– $50 to $90 per ton for central AC and heat pumps

meeting certain efficiency requirements (includes residential)

Utility Programs Commercial Building Colorado Springs UtilitiesLighting retrofit rebate for existing buildings

– T12 to T8s – $9 to $15 per fixture• Peak demand rebate

– $400 per kW with a minimum 10 kW demand reduction– Applicable systems:

• Lighting replacement: T-8 (all sizes), T-5, and HID • Chiller replacement • Motor replacement • HVAC replacement • Thermal storage devices

– Existing buildings or new construction

Commercial Energy Efficiency Example

• 50,000 sf commercial building • T8 lighting of 0.91 watt/sf

– 1.3 watt/sf per ASHRAE 90.1-2001– EPAct tax deduction

• $0.30/sf = $15,000– Xcel incentive

• $5/fixture + $4/reflector = $7,000

Commercial Energy Efficiency Example• 50,000 sf commercial building • 0.55 kW/ton 170 ton scroll chiller

– 0.72 kW/ton per ASHRAE 90.1-2001– EPAct tax deduction

• $0.60/sf = $30,000– Xcel incentive = $6,290

• $10/ton for minimum efficiency = $1,700• $3/ton for higher efficiency than required (0.64 vs. 0.55

kW/ton) = $4,590


• 50,000 sf commercial building • Solar hot water system

– EPAct tax credit of• $30,000 x 30% = $9,000


• 50,000 sf commercial building • $142,500 investment

– $62,500 Lighting; $50,000 Chiller; $30,000 Solar Hot Water

• $67,290 total incentives– $13,290 XCEL Incentives; $9,000 Federal Tax

Credit; $45,000 Federal Tax Deduction– Plus energy savings over time for the life of

the systems

Commercial Energy Case Study• Summit Middle School, Frisco• Pursuing in design:

– High performance windows with light shelves– Displacement ventilation in classrooms– Daylighting with skylights and light tubes in Learning

Communities and new Gymnasium– Electric control of lighting and daylight levels with photocells

and dimming ballasts – High efficiency lighting design – Efficient boilers – High levels of wall and roof insulation – Demand controlled ventilation

• Will save 42% on energy usage and 32% on energy cost with the current design.

Commercial Case Study

• Summit Middle School, Frisco• Pursuing the following EEMs:

– Additional daylighting controls; Heat pipe heat recovery; Indirect evaporative cooling; High efficiency condensing boiler on an outside air reset schedule; Solar ventilation preheat for gymnasium; Re-Install the 2.4 kW photovoltaic system

• Will save 60% on energy usage and 45% on energy cost if all of these EEMs are in the final design.

• First cost: $216,800• Tax deduction: $315,000• Annual energy savings: $137,600• You do the math!

Thank You!

solar energy seminar summit county builders association

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