Residential Solar Power in Midwest

1
Residential Solar Power in Midwest

• Patrick Chapman
• Associate Professor
• University of Illinois at
• Urbana-Champaign

2
Example Illinois Energy Picture

• Dominated by nuclear, coal
• Some wind power
• Solar power ltlt 1
• New Illinois Power Agency reportedly
• Requires 25 of Illinois energy from renewable
  sources by 2025
• Requires 2 by June 1, 2008
• 75 of this must be wind
• Governs net metering and other aspects of power

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Illinois Energy
2006 data 5th in population 10.37/kWh
residential 18 GWh of generation 17.3 GWh coal
nuke
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Illinois Solar Map
4000 Wh/m2 per day Source DOE
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More-Detailed Maps
Provided by Angus Rockett, Univ. of Illinois
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Growth Internationally
Chart from US Photovoltaic Industry Roadmap
(NREL, 2001).
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PVWatts (NREL)

• Based on collected solar data (only select years)
• More reliable that clear-sky calculations
• Available for certain sites
• Specifications
• Tilt latitude
• Azimuth true south
• 0.77 derating factor
• Solar Advisor Model from NREL

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PV Economic Viability

• Varies from place to place
• Solar radiation
• Cloud cover
• Price of electricity
• Real-time pricing vs. fixed pricing
• Installation costs (labor)
• Demand for modules
• Availability of installers
• Rebates and incentives

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Calculations for Select Sites

• For a 1-kW array
• Rockford 1212 kWh/yr (0.089/kWh)
• Springfield 1281 kWh/yr
• Quick multiplier 1250 kWh/yr/kW-installed
• Long Beach 1449 kWh/yr (0.136/kWh)
• Tucson 1617 kWh/yr
• Portland, ME 1280 kWh/yr (0.128/kWh)
• National average in 2007 0.097/kWh (all
  sectors) Hawaii is about 0.21/kWh

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Specifications

• Tilt
• Tilt latitude good rule of thumb
• Slightly shallower is optimal
• Diffuse and reflected light are significant
• Azimuth
• True south optimal
• /- 15 degrees OK
• Watch out for magnetic south
• Derating 77 typical starting point
• PV module hero numbers (few , temperature)
• Inverter efficiency (94)
• Wires (98-99)
• Dirt, aging (few )
• Mismatches (few )

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PV Module Efficiency

• Ratio of electrical power out to sunlight power
  in
• Notice, not included in specifications
• Somewhat overrated figure of merit
• Higher efficiency smaller space
• Higher efficiency higher cost (usually)
• Key figure of merit is /W or /Wh
• Aesthetics also important
• 10 to 14 typical for silicon
• 22 for SunPower modules

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Illinois Rebate Programs

• State rebate program
• 30 of project costs
• Maxes out at 10,000 ltltlt Note, taxable grant
• Limited budget (ran out of money last FY)
• Straightforward application, but takes time/care
• Federal tax credit
• 30 of project costs
• Maxes out at 2,000
• Commercial similar programs
• Illinois Clean Energy Community Foundation
• Other, larger scale projects

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Case Study in Urbana

• 2.87-kW array
• Based on Springfield data
• 3669 kWh/yr
• 30-degree tilt (pitch 7x12)
• 15 degrees west of south
• 0.77 derating (conservative)
• SunPower system
• 14 205-watt modules
• 3300-watt inverter

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Photos Case Study

• Initial work

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More Photos

• Racking

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More Photos

• Modules

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More Photos (Inverter and Monitor)

• Inverter and Monitor

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Finished Project
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Connecting to Ameren

• Somewhat complicated, but cooperative
• Register with FERC as QF
• Qualifying Facility
• Self-certify not difficult, just annoying
• Submit schematic and specs to Ameren
• Pay 100
• Their engineer will approve drawings
• Sign connection agreement
• Can request waivers on insurance, etc.
• Sign QF Rider agreement
• Pick real-time pricing or normal rates (333
  meter)

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Example Schematic
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Real-Time Pricing

• Price peaks more/less with sun

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Pricing

• Smart Power Pricing program
• Administered by CNT
• 2.25 per month participation
• Get wholesale price (Ameren providing wires, this
  is fair)
• Recent legislation allows net metering
• Get the retail price
• Eliminate Smart Power Pricing?
• The Public Utilities Act is amended by adding 5
  Section 16-107.5 as follows
• Ameren to provide free meter (?)

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Sample Billing (9/24-10/23)
PSP Billing (net energy consumed) Total Energy
861 kWh Total Price 51.37 0.0596/kWh
This is the energy supply charge. Distribution
(the wires) costs 0.0245/kWh Total
0.084/kWh
0.71 at noon, 10/8
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Sample Days
Saving 20 to 40 per month compared to flat rate
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Generated Power

• -133 kWh

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One Day Example (kW-hr vs. hr)
Peaks nearly line up, maximizing the
benefit Note this is net generation On
negative load generation, effectively get the
retail price
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Economics

• Upfront cost, about 27,000
• 9 per peak watt, installed
• Breakdown in cost per watt
• 4.50 for PV modules
• 1.00 for inverter
• 3.50 for installer labor and markup
• Rebates
• 8,100 for IL (took eight months to receive
  check)
• 2,000 for Federal
• Net cost 16,900

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Investment Analysis

• At 0.10/kWh 366.90/yr yield
• Simple payback, a mere 46 years!
• This is unfair to PV
• (PV held to near impossible standard)
• Need to look at
• Amortized cost (buying all power upfront)
• Equity
• Increases in electricity prices (real time
  price?)
• Environmental advantages

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More Econ

• Realtors estimate 1,000 savings 20,000 equity
• 366.90 ? 7,338 in equity, and rising
• Net out-of-pocket 9,562
• Assumes there is a willing buyer
• 4 rise in rates 50 increase in prices in 10
  years effects payback and equity

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More Econ

• As part of home mortgage
• 6.75 (30-yr) mortgage, interest is initially
  95/month (66.50 after taxes)
• 33.58 in energy per month about 33 per month
  deficit
• Year 15, prices go up, interest is down
• 55/month savings, 49/month interest
• Equity is 13,200, not much less than the 16,900
  upfront cost

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Other investments

• A 4 CD would have generated 13,536 in income on
  16,900 principle
• After taxes, this is 10,000 yield
• 15 years of electric savings lost
• About 500 per year on average
• 6,000 in 15 years of savings lost
• Net yield on the (CD electricity) is 4,000
• This is about an 8,000 deficit
• This is about 44/month average luxury price
  for the electricity, or about 0.15/kWh
• Gets better with more time

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For Comparison

• Other things that cost 17,000
• BMW 500 over a Toyota Prius
• Extra bedroom
• One semester out-of-state tuition at Illinois
• Etc.
• Conservative?
• Rates may go up faster
• PV costs will go down
• Home interest rates lower
• Unconversative?
• Repairs, maintenance, other risks

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Cost Drivers and Trends

• Manufacturing costs for PV modules going down
• Prices still high due to shortage
• Competition in China coming fast
• Must achieve 3/Wp installed cost and 25 year
  warranty to have grid parity

PV Module Costs
Source Evergreen Solar
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2007 Solar Decathlon

• Dept. of Energy Sponsored Event
• Large national media attention National Mall
• Draw awareness to solar power
• 20 universities to build solar houses
• 10 events (with overall prizes)

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Contests

• Architecture (200 pts)
• Engineering (150 pts)
• Marketability (150 pts)
• Communications (100 pts)
• Comfort Zone, Getting Around, Hot Water,
  Lighting, Appliances (100 pts)
• Energy Balance (100 pts)

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Univ. of Illinois Finish

• 9th overall
• 1st in
• Comfort Zone (best passive solar and HVAC design)
• Marketability (very affordable, ordinary building
  materials, expandable)
• Homes limited to 800 sq. ft.
• Multitude of other limitations and rules
• Accepted for 2009 competition

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Final Illinois House on the Mall
(450k)
Source SD07 photos from solardecathlon.org
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Winning Overall House

• Darmstadt (2M)

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Other Remarkable Houses

• Georgia Tech, Missouri-Rolla

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Other Remarkable Houses, contd

• Santa Clara, Lawrence Tech

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Passive Home Design for 2009

• Passive heating and cooling is largely feasible
  in the Midwest
• PassivHaus Institute US (PHIUS) is located in
  Urbana
• Superinsulated homes (1200 sq. ft.)
• No central air conditioning of furnace
• Earth-tube intake
• Southern exposure adequate for PV a 1-kW system
  zero net energy

Source e-colab.org
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Summary

• PV taking off but still just off the ground
• normal people now taking notice
• Midwest is a poor economic case
• Environmental improvement is worth?
• Still makes most sense to do conventional
  efficiency improvements first
• Insulation, sealing
• Compact fluorescent lighting
• Better HVAC (geothermal, etc)