Photovoltaics notes from a designer, builder and inspector


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Notes on the design and construction of an off grid solar PV system. What to look for in inspecting a PV system.

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  • Photovoltaics notes from a designer, builder and inspector

    1. 1. PHOTOVOLTAICS Second Generation Renewable Energy Technologies Notes from a Designer, Builder and Property Inspector
    2. 2. Professional Background <ul><li>RF Regional Manager </li></ul><ul><li>Intercontinental Satellite Distribution </li></ul><ul><li>North Hollywood , CA 1985-1988 </li></ul><ul><li>RF Satellite and Cable </li></ul><ul><li>Pico Products New Business Development </li></ul><ul><li>Sylmar, CA 1988-1991 & 1996-1998 </li></ul><ul><li>Optical Fiber </li></ul><ul><li>PCO (Joint Venture IBM/Corning Glass) </li></ul><ul><li>Product Manager - Audio/Video Products </li></ul><ul><li>Laser and Pin FET receiver technologies </li></ul><ul><li>Woodland Hills, CA 1992-1995 </li></ul><ul><li>CREIA Certified Inspector since 1999 </li></ul><ul><li>ASHI Certified Inspector </li></ul><ul><li>CLSB General Contractor #791340 </li></ul><ul><li>Licensed Property and Casualty Adjuster (TDI) </li></ul><ul><li>FEMA Certified Disaster Housing Inspector </li></ul>
    3. 3. “ Green” Evolution <ul><li>Chatsworth Residence 2002-2007 </li></ul><ul><ul><li>1900 square feet with 2 car garage & pool </li></ul></ul><ul><ul><li>Installed Energy Efficient Andersons </li></ul></ul><ul><ul><li>Upgraded A/C to 14 SEER </li></ul></ul><ul><ul><li>Xeriscaping with native plants </li></ul></ul><ul><ul><li>Day lighting – Skylights </li></ul></ul><ul><ul><li>Large south facing roof </li></ul></ul>
    4. 4. AIA & Edison Sponsors
    5. 5. The living laboratory “Voluntary Simplicity “ <ul><li>Paso Robles Residence from October 2007 </li></ul><ul><ul><li>1086 square feet. No garage/pool. </li></ul></ul><ul><ul><li>7 Acres on all weather road </li></ul></ul><ul><ul><li>Off Grid PV system </li></ul></ul><ul><ul><li>Water well and septic system </li></ul></ul><ul><ul><li>Garden and compost system </li></ul></ul>
    6. 6. System Design Considerations
    7. 7. Load Requirements <ul><li>Electrical: </li></ul><ul><li>1100 sq. ft. All fluorescent or CFLs </li></ul><ul><li>Energy Star 20 cu. ft. bottom freezer/refrigerator </li></ul><ul><li>Well pressure pump </li></ul><ul><li>Evaporative cooler </li></ul><ul><li>Heating: </li></ul><ul><li>Propane thru wall heater </li></ul><ul><li>Propane stove and water heater </li></ul><ul><li>Back Up Generator: </li></ul><ul><li>Water well (2,500 gal storage tank) </li></ul>
    8. 8. Off Grid PV System <ul><li>(8) Sharp 180 watt PV panels </li></ul><ul><li>Lorentz azimuth array tracker </li></ul><ul><li>Xantech MPPT controller </li></ul><ul><li>(8) Rolls-Surette Batteries 450 amp hours each. 10 year warranty. </li></ul><ul><li>20 kVa diesel/bio diesel back up generator </li></ul><ul><li>Fixed PV systems are only about 60-65% efficient in the real world. Small scale wind turbines are 20-40% (Location, location, location!) </li></ul>
    9. 9. Sharp modules and Lorentz Tracker
    10. 10. Outback FX Invertors and Xantec MPPT Controller
    11. 11. Battery Banks Flooded lead acid Batteries Off Gas Hydrogen - NO Smoking! Needs Lower AND Upper venting at cabinet when enclosed. Take off jewelry to avoid d/c arcing. Can reach 3,000 degrees F and be sustained. Don’t drop your flashlight across the terminals.
    12. 12. Key Issues <ul><li>Tracker mounted PV Panels minimize overall loss. Insolation is 30-40% better with tracker. </li></ul><ul><li>Sharp panels matched to dual Outback invertors. (8X 185= 1480 watts input) </li></ul><ul><li>Outback invertors rated at 1500 watts each </li></ul><ul><li>Xantech controller is MPPT. High efficiency and smoother charging. Optimizes charge rate and prevents over discharge of batteries. 25% improvement. </li></ul><ul><li>8 Rolls 6 volt batteries (2 strings of 4 = 24 volts). </li></ul><ul><li>Usually fully charged by noon. Provides 2-3 days storage capacity during no sun periods. </li></ul><ul><li>Back up generator seldom used. Equalizes batteries and pumps water. Necessary for battery maintenance. </li></ul>
    13. 13. Cost Analysis <ul><li>(8) Sharp panels @ $550 $4,400 </li></ul><ul><li>Lorentz array tracker 1,100 </li></ul><ul><li>Outback Inverters 2,600 </li></ul><ul><li>Xantech controller 575 </li></ul><ul><li>(8) Rolls-Surette Batteries 3,000 </li></ul><ul><li>Total Component Cost $11,675 </li></ul><ul><li>Commercial Cost $19k - $21k </li></ul><ul><li>Based on $190/mo bill – Pay back is 61 months </li></ul>
    14. 14. Ok. Lets go back some… <ul><li>We have very good insolation in California. </li></ul><ul><li>California leads the nation is PV installations. (New Jersey is second!) </li></ul><ul><li>2/3 of the PV systems in the US are in CA </li></ul><ul><li>66% of the CA systems are in Northern California </li></ul><ul><li>SolarLA seeks to equal the entire CA existing PV output by 2014. </li></ul><ul><li>California seeks to have </li></ul><ul><li>1 million systems by 2016 </li></ul><ul><li>122,000 systems installed per year to meet goal </li></ul><ul><li>The US has the 3 rd largest number of PV Systems behind Germany and Spain. Japan is 4 th . </li></ul>
    15. 15. What is solar insolation? <ul><li>What is solar insolation? </li></ul><ul><li>The amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Basically that means how much sunlight is shining down on us. PV systems produce power in proportion to the intensity of sunlight striking the solar array surface. </li></ul><ul><li>Solar radiation striking the Earth varies by region, season, time of day, climate, and air pollution, the yearly amount of energy striking almost any part of the Earth is vast. </li></ul><ul><li>Why is knowing the insolation level useful? </li></ul><ul><li>By knowing the insolation levels of a particular region we can determine the size of the solar photovoltaic panel array that is required. An area with poor insolation levels will need a larger or more panels than an area with high insolation levels. Once you know your region's insolation level you can more accurately calculate array size and energy output. </li></ul>
    16. 16. Solar Insolation Map Average radiation received on a horizontal surface across the continental United States in the month of June Units are in kWh/m2/day.
    17. 17. Annual Energy Production by City per kWSTC* array rating *kilowatt hours at Standard Testing Conditions <ul><li>California Cities (range) </li></ul><ul><li>Arcata 1092 - 1365 </li></ul><ul><li>Shasta 1345 - 1681 </li></ul><ul><li>San Francisco 1379 - 1724 </li></ul><ul><li>Sacramento 1455 - 1819 </li></ul><ul><li>Fresno (Paso Robles) 1505 - 1881 </li></ul><ul><li>Santa Maria 1422 - 1778 </li></ul><ul><li>Barstow 1646 - 2058 </li></ul><ul><li>Los Angeles 1406 - 1758 </li></ul><ul><li>San Diego 1406 - 1758 </li></ul>
    18. 18. What IS a Solar System? <ul><li>Passive Solar </li></ul><ul><li>Solar collectors primarily used to preheat water for water heaters, pools and hydrothermic floors. </li></ul><ul><li>“ Trombone Walls” heated air convection </li></ul><ul><li>PV System </li></ul><ul><li>Electricity Producing </li></ul><ul><li>Photovoltaic panels convert photons to dc current that can be up-converted to standard ac current. </li></ul>
    19. 19. What are the 2 major types of PV Systems? <ul><li>Distributed </li></ul><ul><li>Located near the end use location. </li></ul><ul><li>Usually <1-50 Megawatts </li></ul><ul><li>Can be grid tied. </li></ul><ul><li>Central </li></ul><ul><li>Remotely located near a power transmission grid. </li></ul><ul><li>Can produce gigawatts. </li></ul>
    20. 20. Central PV Systems
    21. 21. OptiSolar SLO County Project <ul><li>550 Megawatts. Largest in US to be completed 2013 </li></ul><ul><li>Uses polished solar collectors to focus energy on pipes filled with liquid sodium that heats water that powers a steam turbine. </li></ul><ul><li>Limited tracking ability. </li></ul><ul><li>Uses large amount H2O </li></ul><ul><li>Needs plant facility </li></ul><ul><li>Noise factor </li></ul>
    22. 22. Austin Texas Energy System <ul><li>Phase One 2009 </li></ul><ul><li>30 megawatts true PV array </li></ul><ul><li>Facility spread out over 620 acres </li></ul><ul><li>Will supply power to 5,000 homes </li></ul><ul><li>100 megawatts by 2020 </li></ul><ul><li>Will provide 30% of city energy needs </li></ul><ul><li>Creates 600 jobs </li></ul>
    23. 23. Distributed PV Systems <ul><li>Residential </li></ul><ul><li>2 Major types: </li></ul><ul><li>Grid Tied </li></ul><ul><li>17,300 Systems </li></ul><ul><li>in California </li></ul><ul><li>Off Grid </li></ul><ul><li>Total Systems Unknown </li></ul><ul><li>Commercial/Industrial </li></ul><ul><li>(Usually Grid Tied) </li></ul>Residential or Industrial?
    24. 24. Distributed Systems
    25. 25. SLO County Installations
    26. 26. As an Inspector… What am I looking at?
    27. 27. Only seems like this at first…
    28. 28. Functions and Components of a PV System <ul><li>Collect Energy </li></ul><ul><li>Photovoltaic cells, panels and arrays </li></ul><ul><li>Convert </li></ul><ul><li>Inverters using transformer-less circuitry up convert 12/24/48v d/c into useful and safe 120/240v a/c. </li></ul><ul><li>Store or Distribute </li></ul><ul><li>Off Grid storage with batteries </li></ul><ul><li>Grid Tied distribution in partnership with utility company. Turns meter “backwards” for “net metering” </li></ul>
    29. 29. Collect Energy <ul><li>Collects energy from photons in sunlight. </li></ul><ul><li>Photovoltaic Panels generate 12v DC </li></ul><ul><li>Modules mfg from silicon based cells grouped together to form a panel. </li></ul><ul><li>Panels combined together to form arrays. Can be configured 12/24/48v DC </li></ul><ul><li>Arrays can be fixed or articulate (Tracking) </li></ul><ul><li>Tracking array 30-40% more efficient by maintaining maximum insolation exposure angle through “solar day” </li></ul>
    30. 30. Major PV Panel Manufacturers
    31. 31. Convert <ul><li>Inverters – “up convert” DC input into stabilized AC output. </li></ul><ul><li>Controllers – Regulate and monitor DC input to invertors (and batteries) </li></ul><ul><li>Two types of controllers </li></ul><ul><li>MPPT and PWM </li></ul><ul><li>May also act as battery chargers </li></ul>
    32. 32. Store or Distribute <ul><li>Store </li></ul><ul><li>Typically flooded lead acid battery banks. </li></ul><ul><li>May be sealed AGM (Absorption Glass Mat) batteries in remote installations. </li></ul><ul><li>Distribute </li></ul><ul><li>Output of invertors directly connected to “grid” of local utility. Energy created is measured to reduce electrical billing. </li></ul>
    33. 33. Typical Battery Banks
    34. 34. Off Grid System Design <ul><li>Small 12 volt d/c Cabin System </li></ul><ul><li>Direct Connected System (Water Pumping) </li></ul><ul><li>Multi Panel Off Grid ( Cell Phone Towers) </li></ul><ul><li>Basic PV System with Generator </li></ul>
    35. 35. Small 12 volt d/c Cabin System Watch out! Often components are electronics devices for auto!
    36. 36. Direct Connected System Common on Farms and Ranches
    37. 37. Multi Panel Off Grid
    38. 38. Basic Off Grid PV System with Generator* * This the System I chose to build.
    39. 39. Grid Tied Utility Interactive <ul><li>Rooftop Utility-Interactive (Grid Tied) System </li></ul><ul><li>Medium Size Residential (Grid Tied) Hybrid a/c and d/c with back up Generator </li></ul><ul><li>Utility-Interactive (Grid Tied) Three-Inverter System </li></ul>
    40. 40. Rooftop Utility-Interactive System (Grid Tied)
    41. 41. Medium Size Residential (Grid Tied) Hybrid a/c and d/c with back up Generator*
    42. 42. Utility-Interactive (Grid Tied) Three-Inverter System Common Commercial/Ranch/Industrial Design
    43. 43. Most Common Systems <ul><li>What the inspector is likely to see. </li></ul><ul><li>Basic Off Grid PV System with Generator </li></ul><ul><li>20% of installed systems in 2009 </li></ul><ul><li>Rooftop Utility-Interactive System (Grid Tied) </li></ul><ul><li>80% of systems reaching 98% by 2020 </li></ul>
    44. 44. Residential Installations
    45. 45. Various Installations
    46. 46. Growth will be in Grid Tied Utility interactive Systems <ul><li>Mandated standards by State legislature </li></ul><ul><li>Rebates from various jurisdictions and Utility providers. </li></ul><ul><li>Federal and State Tax credits </li></ul><ul><li>Off Grid systems are not eligible for rebates. </li></ul><ul><li>Are eligible for Tax Credits. </li></ul>
    47. 47. Benefits of New Federal Incentives <ul><li>30% direct Tax Credit </li></ul><ul><li>State/local/utility credits </li></ul><ul><li>Accelerated depreciation </li></ul><ul><li>Reduced energy bills for 25 years </li></ul><ul><li>Currently can equal 50% of total system cost. </li></ul><ul><li>Adds increased value to residence </li></ul><ul><li>Increased acceptance by lenders </li></ul>
    48. 48. Result? Explosive growth <ul><li>Retro-fitted existing housing stock </li></ul><ul><li>Look for mandated requirements in new home construction. </li></ul><ul><li> </li></ul><ul><li>Increased implementation in commercial and industrial properties to reduce/offset overhead expenses. </li></ul>
    49. 49. Solar Roof Tile Installation
    50. 50. As Inspectors…. <ul><li>How do we report on these systems? </li></ul><ul><li>Do we note the presence of a PV system and defer to a specialist? </li></ul><ul><li>Or do we handle it like a specialty pool/spa report? </li></ul><ul><li>Expert input will be required to define the parameters of a PV report as it pertains to a home inspection. </li></ul><ul><li>But, as in all our reporting, Life/Safety issues MUST be reported. </li></ul><ul><li>Thus, we will be looking at some portions of these systems… </li></ul>
    51. 51. All PV Systems have some or all of these components <ul><li>Modules/Panels </li></ul><ul><li>d/c Disconnect </li></ul><ul><li>Inverter </li></ul><ul><li>a/c Disconnect </li></ul><ul><li>Controller </li></ul><ul><li>Battery Bank </li></ul><ul><li>Cables, Connectors, Grounding and Bonding Devices </li></ul>
    52. 52. Governing Authority <ul><li>Article 690, Solar Photovoltaic Systems of the NEC specifically deals with PV systems, but many other sections of the NEC contain requirements for any electrical system including PV systems [90.2, 720]. When there is a conflict between Article 690 of the NEC and any other article, Article 690 takes precedence [690]. </li></ul><ul><li>National Electrical Code ® and NEC ® are registered trademarks of the National Fire Protection Association, Inc., Quincy, Massachusetts 02269 </li></ul><ul><li>Check Local Building Departments for other Specific Requirements . </li></ul>
    53. 53. Useful Resources <ul><li>Photovoltaic Power Systems And the 2005 National Electrical Code: Suggested Practices </li></ul><ul><li>by John Wiles Southwest Technology Development Institute, New Mexico State University </li></ul><ul><li>This suggested practices manual examines the requirements of the 2005 National Electrical Code (NEC) as they apply to photovoltaic (PV) power systems. The design requirements for the balance-of-systems components in a PV system are addressed, including conductor selection and sizing, overcurrent protection device rating and location and disconnect rating and location. PV array, battery, charge controller, and inverter sizing and selection are not covered, as these items are the responsibility of the system designer, and they in turn determine the items in this manual. Stand-alone, hybrid, and utility-interactive PV systems are all covered. References are made to applicable sections of the NEC. </li></ul><ul><li>Available without charge online. 143 pages. </li></ul><ul><li> </li></ul>
    54. 54. Useful Resources <ul><li>CALIFORNIA ENERGY COMMISSION </li></ul><ul><li>“ A GUIDE TO PHOTOVOLTAIC (PV) SYSTEM DESIGN AND INSTALLATION” </li></ul><ul><li>Prepared by: Endecon Engineering 2001 </li></ul><ul><li>Available without charge online. 40 pages. </li></ul><ul><li> </li></ul><ul><li>Renewable Energy Technology Analysis Project - Pace University </li></ul><ul><li>“ Inspector Guidelines for PV Systems” </li></ul><ul><li>Brooks Engineering Vacaville, CA 2006 </li></ul><ul><li>Available without charge online. 31 pages </li></ul><ul><li>Background, Implications and Requirements </li></ul><ul><li>by John Stevens, Sandia National Laboratories </li></ul><ul><li>“ IEEE-929” (PV Utility Interconnection) </li></ul><ul><li>The only device that the standard impacts is that device where the utility-interface protection functions are accomplished – the inverter. </li></ul><ul><li> </li></ul>
    55. 55. Potential Problem Areas <ul><li>Panel array wiring method- Approved cable </li></ul><ul><li>Panel bonding- Approved connectors </li></ul><ul><li>Disconnects rated for d/c </li></ul><ul><li>Grounding and bonding- Approved connectors </li></ul><ul><li>Listed and rated components </li></ul><ul><li>Batteries- Non approved welding cables </li></ul><ul><li>and corrosion on terminals </li></ul><ul><li>Conductors- Suitable for application </li></ul><ul><li>Clear labeling of components and function </li></ul>
    56. 56. PV Module Interconnect Methods Bus Bar at right = Combiner Box with means of disconnection!
    57. 57. Small System Disconnects Note: Ability to isolate PV Module Input and Load to Batteries.
    58. 58. Wind Damaged PV System
    59. 59. Site Considerations
    60. 60. Improper Module Grounding
    61. 61. ILSCO GBL4-DBT Lug Approved connector
    62. 62. Destroyed Mechanical Terminal From PV System. Fine Wire!
    63. 63. Installing PV Panels on Roofs
    64. 64. More SLO County Installations
    65. 65. Cal Fire Concerns <ul><li>Connected energized systems </li></ul><ul><li>Consider applying the requirements of NEC 440.14 for Air-Conditioning </li></ul><ul><li>and Refrigerating Equipment only requires that the disconnect be “readily </li></ul><ul><li>accessible from the air conditioning or refrigerating equipment.” Following </li></ul><ul><li>this provision would require a clearly marked rooftop disconnect that can </li></ul><ul><li>be easily operated by emergency personnel on the roof with an </li></ul><ul><li>appropriate sign at the service entrance providing (1) a warning of voltage, (2) how to shut down system prior to getting on roof, and (3) location of disconnect on the roof. </li></ul><ul><li>Access to roof peak to vent ridge </li></ul>
    66. 66. Wind Turbine Resources
    67. 67. Thank you! [email_address] Jesse Rusmisel, CCI