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