Solar Electricity
for Home, Farm & Ranch
Using The
Sun To
Produce
Electricity
Bilo; Nov. 2011
E3A Folder & Factsheets:
Solar Electricity for Home, Farm & Ranch
E3A Pyramid
Home Electricity Use
Agriculture Electricity Use
How We Generate Electricity
Electricity Generation
Credit: www.GridVentureBeat.com
Photovoltaics or “PV”
Photo = Light ; Voltaics = Electricity
Credit: www.flickr.com
Credit: http://www.solarplusuk.com/solar-electricity
Photovoltaics
Panel
Some History
Credit: NASA
PV Materials Absorb
the Sun’s Light Energy
PV Materials
Thin-Film
Crystalline Silicon
How Does
It Work ?
Negative Positive
Layer
Layer
Solar Orientation
Do You Have Enough Space for Panels?
2kW system in Arlee, MT
Credit: Courtesy of DOE/NREL
Credit: SolarPlexus, LLC
The rule of thumb for PV panels is 100 square feet of space is needed for
every kilowatt (kW) of electricity produced. For thin-film PV materials
(such as solar shingles), about 175 square feet of space per kW is needed.
Got Shade?
Credit: CleanTechies.com
Solar PathFinder
West
Solmetric’s SunEye
Credit: www.energyefficientheatingandcooling.com
Shading Analysis Tool
Courtesy of Bozeman Green Build
What’s Your Angle?
Summer Solstice
Sun Angle
Spring & Fall Equinox
Sun Angles
45°
Winter Solstice
Sun Angle
0°
The Solar Resource
Miami, Florida
12, 230 watt PV panels = 2,760 watts
= 2.76 PV System
2.76 kW X 5.2 kWh/m²/day X .8 (derate factor)
X 365 days/year = 4,190 kWh of electricity/year
Seattle, Washington
12, 230 watt PV panels = 2,760 watts
= 2.76 PV System
2.76 kW X 3.7 kWh/m²/day X .8 (derate factor)
X 365 days/year = 2,981 kWh of electricity/year
Montana &
Wyoming
Solar
Resource
PV Material + “BOS” = PV System
PV Material
(panels or
shingles, etc.)
Balance of
System (BOS) =
(the remaining
components)
PV Direct Systems
Credit: DOE/NREL
Water-pumping system
Credit: National Center for Appropriate Technology
PV-powered electric fence
Credit: SolarEnergyPros.com
PV-Powered Livestock
Water Pumping
16, 200-watt PV panels = 3,200 watts = 3.2 kW
Powers the pump system.
All Credits: Oasis Montana, Inc.
PV-Powered
Irrigation
Water Pumping
4, 40-watt PV panels = 160 watts
Powers the miniature pivot system motors.
Irrigation Guide:
Ch. 12: Energy Use
& Conservation
Solar-Powered Pump
System Calculator
Cost$
• Cost depends on a variety of factors: the solar
resource, PV materials used, and system type and
size, etc.
• Small to medium grid-tied systems range from
$5,000 to $7,000 per kilowatt (kW). Larger
systems are less per installed kW.
• An energy efficient home, farm and ranch can
purchase a smaller, less expensive PV system and
meet more of the electrical load using the sun.
Residential Incentives
(as of October 2011)
1. 30% Federal Tax Credit (exp. 12-31-16)
2. Montana State Tax Credit (no exp. date)
$500 for 1 taxpayer; $1,000 for a household
3. Some utilities offer rebates for renewable
energy systems and energy efficiency upgrades.
DSIRE Website: www.dsireusa.org
4. DOE’s Lawrence Berkeley National Laboratory
study: homes with PV systems sell at a premium: in
CA, a 3.1 kW avg. system size adds $17,000 value.
Residential Grid-Tied PV System Sizing & Cost Comparison
System
Sizing
Costs
Incentives
Savings &
Payback
For 100% of Electricity
Produced by the Sun
PV System Size
PV Panel Requirement
Initial Upfront Cost
@ $5,373/kilowatt
Northwestern Energy
Rebate
Federal Tax Credit
Montana Tax Credit
Final Net Cost
$ Saved on Electricity
Simple Payback
(Bilo, Oct. 2011)
Energy- Efficient Home
Electricity Consumption
438 kilowatt-hours
(kWh)/month
438 kWh
Average Montana Home
Electricity Consumption
856
kWh/month
856 kWh
3.7 kW
16, 230-watt panels
7.2 kW
31, 230-watt panels
$19,880
$38,686
- $6,000
- $6,000
- $4,164
- $1,000
- $9,806
- $1,000
$ 8,716
$ 21,880
$704
12 years
Conservation & Efficiency ROCK!
Grid-Tied System Lifespan: Panels = 25+ years; Inverter = 20+ years
$ 1,360
16 years
Energy Efficiency
Looking for these labels makes shopping for
energy efficient fixtures and appliances easy.
Resources
Energy Savers Booklet:
Tips on Saving Energy & Money At Home
Available on-line at: www.energysavers.gov/pdfs/
energy_savers.pdf
Montana
Energy Savers Guidebook:
Practical Ways to Save Money and Improve Comfort
Available on-line at:
www.deq.mt.gov/Energy/pdf/MTESG10-2008.pdf
Resources
Websites:
• U.S. Department of Energy’s Energy Savers website
www.energysavers.gov
• U.S. Environmental Protection Agency’s Energy Star
website www.energystar.gov/
Magazines: home power and Home Energy
A Consumer’s Guide:
Get Your Power From the Sun
Available on-line at:
www.nrel.gov/docs/fy04osti/35297.pdf
Farm Energy Efficiency
Checklist & Tips
Website
http://www.ag.ndsu.edu/pubs/ageng
/structu/ae1366.pdf
Energy-Efficient Irrigation Tips
- Use low pressure versus
high pressure systems
- Check for and fix pipe leaks
- Properly size and maintain
sprinkler nozzles
- Use efficient motors and
pumps
- Use ET-based irrigation
tools to prevent underand overwatering
- Convert to drip irrigation
Energy-Efficient Grain Drying
• Field dry as much
as possible
• Check and calibrate
moisture and
temperature
sensors
• Reduce overdrying
• Recover heat
• Use natural air or
low-temperature
Natural-Air Drying Bin Schematic. drying when
feasible
Credit: University of Minnesota Extension
Installation
The Components
For PV materials, ask about STC or PTC test conditions.
For PV materials and BOS components, ask about
Underwriter’s Laboratories (UL) certifications.
The Installer
Make sure the installer you hire is qualified.
Ask about certifications, trainings, or licenses.
To find installers in Montana, contact the Montana Renewable
Energy Association: www.montanarenewables.org.
In Wyoming, visit Cooperative Extension’s website:
www.uwyo.edu/renew-energy
What’s Next?
E3A Folder &
Factsheets:
Solar Electricity
for Home, Farm
& Ranch
Thank You!
Susan Bilo
Montana State University
Extension
(406) 994-2225
susan.bilo@montana.edu
EXTRA SLIDES
The following slides can help address specific
questions/discussions related to:
• Energy Terms: Power & Energy; Watts and
kilowatt-hours (kWh)
• System Sizing & Cost Comparison Calculations
• Energy Subsidies
• Solar Cell & Vehicle Efficiency
Watts vs Kilowatthours (kWh), or
Power vs Energy
• Power is described in units of Watts. A 23-watt compact
fluorescent light (CFL) bulb is designed to use 23 watts of
power to produce light.
• Energy is described in units of Watt-hours
Example: If turned on for one hour, a 23-watt CFL uses 23
watt-hours of Energy. If left on for 2 hours, it uses 46 watthours of Energy (23 watts x 2 hours = 46 watt-hours)
• 1,000 watts = I kilowatt (kW)
• 1,000 watt-hours = 1 kWh
If the 23-watt CFL is left on for 44 hours, it uses a little over
1 kilowatt-hour (kWh) of Energy
(23 x 44 = 1,012 watt-hours)
PV System Sizing & Cost Comparison
SYSTEM SIZING
A. Average kWh Consumed/Month
B. Convert to watt-hours/month:
A. x 1,000 = watt-hours/month
C. Convert to watt-hours/day:
B. ÷ 30 = watt-hours/day
D. Determine % of Solar Electricity:
C. x % = watt-hours/day
E. Daily Watts Needed Based on
Local Solar Radiation:
D. ÷ 4.74 KwH/m2/day
(Bozeman, MT)
F. Account for System Inefficiencies
E. x 1.2
G. Convert to kW for System Size:
F. ÷ 1,000 watts = kW
H. Determine # of panels needed:
- Using 230-watt PV Panels
-Using 320-watt PV Panels
(Bilo, Oct. 2011)
Energy Efficient (3 person) Home
= 146 Kwh/person/monthX3 =
438 kWh
Average Montana Home
MT Household: 2.35; thus, roundedup to 3 (2010 Census Data)
438 kWh/month
438 kWh/month x 1,000 =
438,000 watt-hours/month
438,000 ÷ 30 = 14,600 watthours/day
14,600 x 1.0 = 14,600 watthours/day
856 kWh/month
856 kWh/month x 1,000 =
856,000 watt-hours/month
856,000 ÷ 30 = 28,533 watthours/day
28,533 x 1.0 = 28,533 watthours/day
14,600 ÷ 4.74 = 3,080 watts
28,533 ÷ 4.74 = 6,020 watts
3,080 x 1.2 = 3,696 watts
6,020 x 1.2 = 7,224 watts
3,696 ÷ 1,000 = 3.7 kW System
7,224 ÷ 1,000 = 7.2 kW System
3,696 watts ÷ 230 watts = 16,
230-watt panels
3,696 watts ÷ 320 watts = 12,
320-watt panels
7,224 watts ÷ 230 watts = 31, 230watt panels
7,224 watts ÷ 320 watts = 23, 320watt panels
Do you have room on your roof for 23 PV Panels?
PV System Sizing & Cost Comparison
(Bilo, Oct. 2011)
Energy Efficient (3-person) Home
Using 438 kWh/month
Average Montana Home
Using 856 kWh/month
3.7 x $ 5,373 = $ 19,880 for a 3.7 kW
PV System
that provides 100% of the home’s
electricity
3.7 kW = 3,700 watts x $3 = $11,100
$ 6,000
7.2 x $5,373 = $ 38,686 for a 7.2 kW
PV System
that provides 100% of the home’s
electricity
7.2 kW = 7,200 watts x $3 = $21,600
$ 6,000
SYSTEM COST
Grid-Tied System Average Cost
Range
Without Incentives: $5,000$7,000 per kW
Northwestern Energy Rebate
$3/watt; ($6,000 cap)
30% Federal Tax Credit (Expires
Dec. 2016)
Montana State Tax Credit
Net Cost After Incentives
Cost Savings Estimate Formula:
PV system Size x Energy
Production Factor x Electricity
Rate
Simple Payback Formula:
Cost ÷ Cost Savings
$13,880 x 30% =
$ 4,164
$32,686 x 30% =
$ 1,000
$ 9,806
$ 1,000
$19,880 – 6,000 – 4,164 – 1,000
$38,686 – 6,000 – 9,806 – 1,000
= $ 8,716
= $ 21,880
3.7 kW x (4.74 kWh/m2/day {from E.} 7.2 kW x (4.74 kWh/m2/day {from E. }
x 365 days/year) x $.11/kWh =
x 365 days/year) x $.11/kWh =
$ 704 saved per year with this PV
$ 1,370 saved per year with this PV
system
system
$8,716 ÷ $704 = 12 years
$21,880 ÷ $ 1,370 = 16 years
Grid-Tied System Lifespan: Panels = 25+ years; Inverter = 20+ years
U.S. Government Subsidies
to Energy Sources, 2002-2008
-
Sept. 2009 Environmental Law Institute Publication
Fossil Fuel subsidies: $72 Billion
Renewable Energy subsidies: $29 Billion
Almost ½ of the Renewable Energy subsidies are for
corn-based ethanol.
- Most of the largest subsidies given to the Fossil Fuel
industry are permanent provisions written into the
U.S. Tax Code.
- Many Renewable Energy subsidies are time-limited
initiatives implemented through energy bills.
http://www.fueleconomy.gov/feg/atv.shtml