Photovoltaic Design & Installation For Dummies

Ryan Mayfield has been working in the renewable energy field since 1999. He is President of Renewable Energy Associates, a consulting firm providing design, support, and educational services for commercial photovoltaic systems. He is also Photovoltaic Systems Technical Editor for StarPro magazine, where he regularly contributes feature articles.

• Introduction 1About This Book 1Conventions Used in This Book 2What You’re Not to Read 3Foolish Assumptions 3How This Book Is Organized 3Part 1: Here Comes the Sun: Shedding Some Light on PV Systems 4Part 2: Digging into Complete System Details 4Part 3: Sizing a PV System 4Part 4: Installing a PV System 4Part 5: The Part of Tens 5Icons Used in This Book 5Where to Go from Here 5Part 1: Here Comes the Sun: Shedding Some Light on PV Systems 7Chapter 1: The Photovoltaic Revolution 9Peeking into the Past, Present, and Future of PV Installations 9Acquainting yourself with typical PV applications 10Checking out PV pros and cons 10Looking into the future of PV 11Introducing PV Components and Systems 11Knowing Your Electricity A-B-Cs 12Solar Resource 101 13Surveying a PV System Site 13Delving into PV System Details 14PV modules 14Batteries 14Charge controllers 15Inverters 15Wiring and safety devices 15Sizing a PV System 16Grid-direct systems 16Battery-based systems 16Conductors and safety devices 17Bringing a PV System to Life 17Permitting 17Staying safe 17Putting together the mechanical parts 18Adding the electrical parts 18Commissioning, inspecting, and maintaining a system 19Introducing the Sections of Code You Need to Know 20Chapter 2: Checking Out Common Components and Systems 21Introducing the Components That Make Up PV Systems 21PV modules and racking 22Battery bank 23Charge controller 24Inverter 24Loads 25Load centers 26Disconnects and overcurrent protection 27Utility interconnection 27Differentiating between PV System Types 29Grid-direct systems 29Battery-based systems 31Figuring Out the Right System Type for Any Situation 34The customer is connected to the grid 34The customer isn’t connected to the grid 35Chapter 3: Powering through Electricity Basics 37Going with the Flow: Current 38Understanding amps 38Distinguishing between direct current and alternating current 39Measuring current with a meter 40May the (Electromotive) Force Be with You: Voltage 43Grasping the concept of voltage 43Getting a grip on nominal voltage and operating voltage 43Measuring voltage 44Making a Stop: Resistance 46Introducing ohms 47Measuring resistance 47Connecting Current, Voltage, and Resistance with Ohm’s Law 49Pondering Power and Energy 50Recognizing the differences between power and energy 50Relating power to current, voltage, and resistance with the power equation 51Calculating energy in terms of watt-hours 53Introducing amp-hours, a companion to watt-hours 53Wrapping Together Current, Voltage, Resistance, Power, and Energy 54Another Electricity Concept: Circuit Configurations 55Series 56Parallel 57Series-parallel 58Chapter 4: Warming Up to the Solar Resource 59High (Or Low) Energy: Solar Radiation 60Distinguishing between direct radiation and diffuse radiation 60Determining the intensity of solar radiation: Irradiance 61Calculating solar radiation energy: Irradiation 65Just for a day: Peak sun hours 66Examining the Effects of the Sun’s Path on the Earth 69Getting a grip on seasonal effects 70Understanding the sun’s relationship to your location: Altitude and azimuth 72Ticking off solar time 74Interpreting sun charts 74Opening up to the solar window 76Positioning PV Modules to Make the Most of the Solar Resource 77Introducing tilt angle 77Orienting your array to the azimuth 79Chapter 5: Properly Selecting a Site for a PV System 81Setting the Stage for a Site Survey 82Putting aside enough time 82Creating a standard site-survey form 83Toting a site-survey bag 83Picture This: Documenting Your Entire Site Survey with Digital Photos 84Collecting Basic Information during a Site Survey 86General site information 86Structural and mechanical information 87Electrical information 89Measuring Information in Degrees 90Understanding magnetic declination 91Calculating the array’s tilt angle and azimuth 93Exploring Shading-Analysis Tools 95Interpreting the Data and Bringing It All Together 97Analyzing reports from your shading-analysis tool 98Considering the total solar resource factor 98Using other collected information to plan out the design and installation 100Part 2: Digging Into Complete System Details 103Chapter 6: PV Modules: From Sand to Electricity 105Creating Solar Electricity: It All Starts with a Cell 106Getting a grip on cell construction and manufacturing 106Connecting cell construction to the photovoltaic effect 108Reviewing Common Types of PV Modules 108Checking out crystalline modules 109Looking at thin film modules 111Pointing Out Electrical Specifications on PV Modules 113Current specifications 114Voltage specifications 115Maximum power point 116Voltage temperature coefficient 117Power tolerance 118Series fuse rating 118Surveying Test Conditions for PV Modules 118Standard test conditions 119Environmental effects on standard test conditions 120Relating Current and Voltage in IV Curves 122An IV curve with varying temperature 123An IV curve with varying irradiance 124Chapter 7: The Basics of Batteries 127The Fundamentals of Battery Anatomy and Operation 128Constructing a battery, from cell to bank 128Discovering how batteries charge and discharge 130Comparing Different Types of Batteries 133Lead-acid batteries 133Lead-calcium batteries 136Nickel-cadmium batteries 136Comprehending Battery Capacity 137Considering the C rate for capacity 137Recognizing factors that affect capacity 138Specifying Batteries 141Specifying the type of battery to use 141Specifying the battery bank size 142Chapter 8: Keeping Current and Voltage in Check: Charge Controllers 147The Essentials of Charge Controllers 148Seeing how a charge controller works in stages 148Surveying special effects provided by some charge controllers 151Maximum Power Point Tracking Technology 153How MPPT works 153The pros and cons of MPPT controllers 154Pulse-Width Modulation Technology 155How PWM works 155The pros and cons of PWM controllers 156Specifying a Charge Controller 156Chapter 9: Inverters: AC (From) DC 157Getting the Goods on Grid-Direct Inverters 158Basic operation 158Standard features 159Power output sizes 162The importance of transformers 162Investigating Battery-Based Inverters 164Utility-interactive inverter operation 165Stand-alone inverter operation 166Standard features for all battery-based inverters 167Sizes of battery-based inverters 168Low-frequency transformer technology 168Specifying Any Inverter 168Grid-direct 169Battery-based 170Chapter 10: Staying Secure: Wiring and Safety Components 173Defining the Circuits in a PV System 174Checking Out Types of Conductors 175USE-2 176PV wire 176Building wiring 177Battery wiring 178Ground wiring 178Considering Kinds of Conduit 179Metallic conduit 179Nonmetallic conduit 180Delving into Disconnects 181Perusing Overcurrent Protection Devices 182Circuit breakers 183Fuses 183Focusing on Ground Fault Protection 184Looking at the Basics of Labels 185Part 3: Sizing a PV System 187Chapter 11: Sizing a Grid-Direct System 189First Things First: Evaluating the Budget and the Available Array Area 190Estimating the Site’s Annual Energy Production 191Sizing the Array to Meet Your Client’s Energy Consumption 193Determining annual energy consumption 193Looking at contract options with the utility 194Using consumption and contract options to select an array’s needed power value 195Getting Ready to Match an Inverter to an Array 196Matching Power Values for an Array and an Inverter 197Coming Up with the Right Voltage Values for Your Array and Inverter 199Establishing the inverter’s AC voltage 200Defining the inverter’s DC voltage window 200Calculating the modules’ maximum DC voltage contribution 201Figuring out the modules’ minimum DC voltage contribution 208Bringing It All Together: Combining Your Power and Voltage Information 213One Last Check: The Inverter’s Maximum Current Input 214Chapter 12: Sizing a Battery-Based System 215Get Loaded: Looking at Loads in a Battery-Based System 216Evaluating the loads that the battery bank must serve 216Calculating the energy required during an outage for utility-interactive systems 219Determining the average daily energy consumption for stand-alone systems 219Sizing the Battery Bank 222Inverter efficiency 222The days of autonomy 223The temperature used for battery operation 223The depth of discharge 224Nominal voltages 225Figuring out the battery capacity you need 226Strung along: Wiring the battery bank 227Sizing the PV Array 229Sizing the array in a utility-interactive system 229Sizing the array in a stand-alone system 230Sizing the Charge Controller 232Voltage specifications 233Power or amperage specifications 234A check before you move on: Comparing the array size to the battery capacity 236Sizing the Inverter 236Viewing voltage output 237Calculating the power draw 237Staying in charge 238Looking at surge ratings 238Evaluating inverter and array power output 239Incorporating a Generator 239Generator features 240Generator sizing 241Chapter 13: Sizing Conductors, Conduit, and Safety Components 243Conductor Sizing 101 244Defining the PV circuits’ maximum and continuous current 245Calculating non-PV circuits’ maximum current 246Considering conditions of use with some handy tables 247Putting together the details to determine conductor sizing 250Accounting for voltage drop after you size your conductors 253Sizing Conduit 257Sizing Overcurrent Protection Devices and Disconnects 258Beginning with a few basics 258Placing protection on PV circuits 259Protecting inverter circuits 260Part 4: Installing a PV System 261Chapter 14: The Permitting Process 263Obtaining Permits before You Install a PV System 263In the beginning: Having the right licenses and certifications 264Home grown: Permitting for residential systems 265Big business: Permitting for commercial systems 269Not Just Pretty Pictures: Creating Drawing Sets 272Calling out components clearly 273Depicting equipment locations 273Showing conductor-sizing calculations 273Jotting down job notes 274Chapter 15: Staying Safe Anytime You Work on a PV System 275Getting a Grip on General Construction Site Safety 276Identifying job-site obstacles and putting on protective gear right away 276Safely working alone and with others 277Taking in tips for tool safety 278Limiting your exposure to the elements 278Stowing a first-aid kit on the job site 279Looking at Ladder Safety 279Selecting your stash of ladders 279Properly setting up any ladder 281Raising the Issue of Rooftop Safety 282Restraining yourself with fall protection 283Storing your tools 283Maintaining safe walkways 285Examining Electrical Safety 285Staying aware of general shock hazards 285Working with circuits 286Charging Ahead with Battery Safety 290Chapter 16: Assembling the Mechanical Parts 293Surveying PV Array Mounting Methods 294Roof mounting 295Ground mounting 300Top-of-pole mounting 302Building-integrated mounting 303Considering Loading When You Mount an Array on a Roof 305Following building codes 305Accounting for additional dead load 305Looking at live loads 307Properly Attaching an Array to a Roof 309Making attachments with lag screws 309Sealing roof penetrations with flashing 310Supporting Ground and Top-of-Pole Mounting 313Chapter 17: Integrating the Electrical Elements 315Location Is Everything: Knowing Where to Place Electrical Equipment 316Manufacturers’ requirements for equipment locations 316Locations for disconnecting means 317Combiner boxes and junction boxes and wiring, oh my! 318Working on Wiring 319Seeing red (and green and white): Color-coding 319Managing wires on PV modules 321Protecting wires with conduit 322Bonding Yourself to Grounding 323Equipment grounding 323System grounding 326Connecting to the Utility 329Determining the utility’s requirements 329Making a load side or line side connection 331Chapter 18: Commissioning, Inspecting, and Maintaining a PV System 335Making a List and Checking It Twice: Preparing for Commissioning 336Mechanical elements? Check! 336Electrical elements? Check! 337Start ’Er Up: The Commissioning Process 341Putting safety first 342Gathering the gear you need 342Commissioning different types of systems 343Verifying that the system is working 347Arming Yourself for Inspection Issues 349Not having “a neat and workmanlike manner” 350Forgetting about aesthetics 350Failing to manage conductors on the array 350Neglecting to label the system 351Surveying System Maintenance 353Mechanical maintenance 354Electrical maintenance 354Maintenance on a higher level: Taking care of battery banks 355Part 5: The Part of Tens 359Chapter 19: Ten Ways to Avoid Common Code Mistakes 361Providing Proper Working Clearance 362Supplying the Right Structural Support 362Keeping Water out of Buildings with Flashing 363Ensuring All Conductors Have the Necessary Ratings 363Managing the Conductors on Modules 364Selecting the Correct Conduit 364Locating the Disconnects 365Grounding the Equipment 365Grounding the System 366Labeling the System Properly 366Chapter 20: Ten Ways to Maximize Energy Production for Your Clients 367Select the Right Site 367Orient the Array Correctly 368Configure the Array Properly 368Work within the Limits of the Utility Voltage 369Choose the Correct Inverter 369Size Conductors Appropriately 370Keep the Components Cool 370Advise Clients to Monitor Their System 371Clean the Array Periodically 371Inspect the Array Annually 372Index 373