Freshman Clinic

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Freshman Clinic

• Intro to Solar and Wind

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Wind PV Production (96-03)
Wind production PV production
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Wind Grows Another 20 in 04
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PV Market Keeps Growing in 04
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NJ Wind Resources
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Wind Turbines
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Wind Turbines

• A wind turbine obtains its power input by
  converting the force of the wind into a torque
  acting on the rotor blades.
• The amount of energy which the wind transfers to
  the rotor depends on the density of the air, the
  rotor area, and the wind speed.

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Wind Turbines

• A wind turbine will deflect the wind before it
  even reaches the rotor plane which means that all
  of the energy in the wind cannot be captured
  using a wind turbine.

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Wind Turbine Energy

• The annual energy delivered by a wind turbine can
  be estimated by using the equation

The cost of electricity will vary with wind
speed. The higher the average wind speed, the
greater the amount of energy, and the lower the
cost of electricity
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Wind Power Classifications
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Delaware Bay / Coastal Wind Speeds

• Areas along shore or in mountains may be ideal
  for wind power
• Wind speeds as low as
• 4.5 -5.5 m/s
• for res farms/comm
• gt6.0 m/s can be used
• for power farms
• At 6.5 m/s, electricity can be below
• 0.07/kWh

True Wind Solutions
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2005 NJCEP Rebates

• Wind and Sustainable Biomass Systems
• Systems lt 10 kW 5.00/watt
• Maximum incentive (60 of system costs)
• Systems gt 10kW
• First 10 kW 3.00/watt
• gt 10 to 100 kW 2.00/watt
• gt 100 to 500 kW 1.50/watt
• gt 500 kW, up to 1000 kW 0.15/watt
• Maximum incentive (30 of system costs)

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Sample 10 kW Turbine in NJ

• Class 3 winds at ground 5.5 m/s, 24 m (80ft)
  6.3 m/s aloft
• Power generated is 18,000 kWh/year
• Turbine 24,750
• Tower 6,800
• Install/Misc 5,500
• NJCEP Rebate (60) 22,230
• Net Cost 14,820
• 15 year electric cost 5.5/kWh
• Simple Payback 7.5 years

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New Jersey Anemometer Loan Program

• USDOE, NJBPU/NJCEP, Rutgers and Rowan University
  have partnered to offer free wind energy analysis
  to farms seriously considering wind
• 1 year onsite wind measurement
• Tower and anemometer installed at no charge
• Contacts
• NJCEP Alma Rivera 1.973-648-7405 or email
  alma.rivera_at_bpu.state.nj.us
• Rowan Dr. Peter Mark Jansson 1.856.256.5373 or
  email jansson_at_rowan.edu
• Rutgers Dr. Michael R. Muller 1.732.445.3655 or
  email muller_at_caes.rutgers.edu

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New Jersey Anemometer Loan Program

• Regional Data from the South Available OnLine
• http//www.rowan.edu/cleanenergy
• UNDER CONSTRUCTION

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New Jersey Wind Power
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Solar Resources - Direct Beam
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Solar Resources Total Diffuse
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Historic PV price/cost decline

• 1958 1,000 / Watt
• 1970s 100 / Watt
• 1980s 10 / Watt
• 1990s 3-6 / Watt
• 2000-2006
• 1.8-2.5/ Watt (cost)
• 3.50-4.75/ Watt (price)

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PV cost projection

• 1.50 ? 1.00 / Watt
• 2007 ? 2008
• SOURCE US DOE / Industry Partners

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Solar PV - Practical Information

• Approx South Facing Roof or field
• Roof angles from 20-50 degrees
• Less than 200 from loads
• Every 70 square feet of area can yield up to 1000
  kWh per year in New Jersey

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PV technology efficiencies

• 1970s/1980s ? 2003 (best lab efficiencies)
• 3 ? 13 amorphous silicon
• 6 ? 18 Cu In Di-Selenide
• 14 ? 20 multi-crystalline Si
• 15 ? 24 single crystal Si
• 16 ? 37 multi-junction concentrators

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Amorphous Si
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Amorphous Si
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Cadmium Telluride
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Multi-crystalline Si
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Multi-crystalline Si
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Single Crystal Si
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Semi-Conductor Physics

• PV technology uses semi-conductor materials to
  convert photon energy to electron energy
• Many PV devices employ
• Silicon (doped with Boron for p-type material or
  Phosphorus to make an n-type material)
• Gallium (31) and Arsenide (33)
• Cadmium (48) and Tellurium (52)

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p-n junction

• When junction first forms as the p and n type
  materials are brought together mobile electrons
  drift by diffusion across it and fill holes
  creating negative charge, and in turn leave an
  immobile positive charge behind. The region of
  interface becomes the depletion region which is
  characterized by a strong E-field that builds up
  and makes it difficult for more electrons to
  migrate across the p-n junction.

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Depletion region

• Typically 1 µm across
• Typically 1 V
• E-field strength gt 10,000 V/cm
• Common, conventional p-n junction diode
• This region is the engine of the PV Cell
• Source of the E-field and the electron-hole
  gatekeeper

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Bandgap energy

• That energy which an electron must acquire in
  order to free itself from the electrostatic
  binding force that ties it to its own nucleus so
  it is free to move into the conduction band and
  be acted on by the PV cells induced E-field
  structure.

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Band Gap (eV) and cutoff Wavelength

• PV Materials Band Gap Wavelength
• Silicon 1.12 eV 1.11 µm
• Ga-As 1.42 eV 0.87 µ m
• Cd-Te 1.5 eV 0.83 µ m
• In-P 1.35 eV 0.92 µ m

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Photons have more than enough or not enough
energy

• Sources of PV cell losses (?15-24)
• Silicon based PV technology max(?)49.6
• Photons with long wavelengths but not enough
  energy to excite electrons across band-gap (20.2
  of incoming light)
• Photons with shorter wavelengths and plenty
  (excess) of energy to excite an electron (30.2
  is wasted because of excess
• Electron-hole recombination within cell (15-26)

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p-n junction

• As long as PV cells are exposed to photons with
  energies exceeding the band gap energy
  hole-electron pairs will be created
• Probability is still high they will recombine
  before the built-in electric field of the p-n
  junction is able to sweep electrons in one
  direction and holes in the other

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Generic PV cell
Incoming Photons
Top Electrical Contacts
electrons ?
- - - - Accumulated Negative Charges - - - -
n-type
Holes
E-Field
Depletion Region


- - - - - -
- - -
Electrons
p-type
Accumulated Positive Charges
Bottom Electrical Contact
I ?
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PV Module Performance

• Standard Test Conditions
• 1 sun 1000 watts/m2 1kW/m2
• 25 oC Cell Temp
• AM 1.5 (Air Mass Ratio)
• I-V curves
• Key Statistics VOC, ISC, Rated Power, V and I at
  Max Power

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PV specifications (I-V curves)

• I-V curves look very much like diode curve
• With positive offset for a current source when in
  the presence of light

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From cells to modules

• Primary unit in a PV system is the module
• Nominal series and parallel strings of PV cells
  to create a hermetically sealed, and durable
  module assembly
• DC (typical 12V, 24V, 48V arrangements)
• AC modules are available

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PV Module Performance

• Temperature dependence
• Nominal operating cell temperature (NOCT)

Tc cell temp, Ta ambient temp (oC), S
insolation kW/m2
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PV Output deterioration

• Voc drops 0.37/oC
• Isc increases by 0.05/oC
• Max Power drops by 0.5/oC

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BP 3160

• Rated Power 160 W
• Nominal Voltage 24V
• V at Pmax 35.1
• I at Pmax 4.55
• Min Warranty 152 W
• NOTE I-V Curves

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From modules to arrays

• Method
• First Determine Customer Needs (reduce)
• Determine Solar Resource (SP, model, calcs)
• Select PV Modules or
• Select DC-AC Inverter
• Look for Maximum Power Tracking Window
• Max DC voltage Current
• Assure Module Strings Voc and Isc meet inverter
  specifications

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See Mesa Environmental Solar Audits

• Spreadsheet Customer Monthly Consumption
• Determine potential Shade Free Sites
• ID source for local Solar Resource Info
• Model (PVWATTS, PV FCHART, NJCEP)
• Weather Service Data
• Actual measurements from region

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Remember

• PV modules stack like batteries
• In series Voltage adds,
• constant current through each module
• In parallel Current adds,
• voltage of series strings must be constant
• Build Series strings first, then see how many
  strings you can connect to inverter

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Match Modules With Inverter

• Find Optimal Fit of Series Strings
• TO BE IN MAX POWER TRACKING WINDOW
• Assure module s do not exceed Voc
• Find Optimal of Strings in Parallel
• TO MEET MODULE POWER RATING
• CURRENT TO BE LESS THAN MAX Isc
• Are Modules and Inverter a good match?
• Overall Hardware Utilization efficiency

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Putting it all Together

• Customer Needs (energy usage ? reduce)
• PV System Design Requirements
• Solar Resource Assessment
• Potential Sites on Customer Property
• PV Module Inverter Selection
• Wiring Diagram
• System Economic Analysis

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Wiring the System
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PV system types

• Grid Interactive and BIPV
• Stand Alone
• Pumping
• Cathodic Protection
• Battery Back-Up Stand Alone
• Medical / Refrigeration
• Communications
• Rural Electrification
• Lighting

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Grid Interactive
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Grid-interactive roof mounted
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Building Integrated PV
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Stand-Alone First House
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Remote
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NJ Incentives

• NJ Clean Energy Program
• 70 rebate for grid connected systems up to 10kW
• Smaller rebates for increments above 10kW
• Net Metering to 100kW
• Solar Renewable Energy Certificates
• NJ RPF requires 2 MW 2004 ? 10 MW 2008
• Currently trading about 200/MWh

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Economic / Market Impacts

• Systems would have 25-30 year payback
• With NJCEP reduces to 10 year
• With SREC could be less than 7 year