Bifacial Photovoltaics: Technology, Applications and Economics

Description

Bifacial photovoltaic (PV) modules are able to utilize light from both sides and can therefore significantly increase the electric yield of PV power plants, thus reducing the cost and improving profitability. Bifacial PV technology has a huge potential to reach a major market share, in particular when considering utility scale PV plants. Accordingly, bifacial PV is currently attracting increasing attention from involved engineers, scientists and investors. There is a lack of available, structured information about this topic. A book that focuses exclusively on bifacial PV thus meets an increasing need. Bifacial Photovoltaics: Technology, applications and economics provides an overview of the history, status and future of bifacial PV technology with a focus on crystalline silicon technology, covering the areas of cells, modules, and systems. In addition, topics like energy yield simulations and bankability are addressed. It is a must-read for researchers and manufacturers involved with cutting-edge photovoltaics. Contents......Page 8 Acknowledgements......Page 14 About the authors......Page 16 1.1.1 PV becomes the most cost-effective electricity source......Page 26 1.1.2 What PV technology will win at the end?......Page 29 1.2.1 Short bifacial history......Page 30 1.2.2 Bifacial status......Page 32 1.2.3 Bifacial future......Page 33 1.2.4 Changing to cost per kWh thinking instead of cost per Wp mentality......Page 34 1.3.1 Latest bifacial publications and presentations......Page 36 1.3.2 Chapters of our bifacial book......Page 37 References......Page 40 2.1 Introduction......Page 42 2.2 History of bifacial cells (from 1960 to 2016)......Page 44 2.3.1 Bifaciality factor......Page 47 2.3.2 Parameters influencing the bifaciality factor j......Page 48 2.3.3 Design of bifacial cells......Page 52 2.4.1 Measuring bifacial cells......Page 53 2.4.2 IV measurements under bifacial irradiation......Page 56 2.5.1 Heterojunction solar cells......Page 57 2.5.2 n-PERT solar cells......Page 60 2.5.3 p-PERT solar cells......Page 65 2.5.4 p-PERCþ solar cells......Page 71 2.5.5 Bifacial back contact solar cells......Page 79 2.6.1 Industry status in 2017......Page 83 2.6.2 Solar cell technology predictions (ITRPV)......Page 84 References......Page 85 3.1.1 Design considerations for bifacial modules......Page 96 3.1.2 Cell-to-module loss analysis in bifacial PV modules......Page 98 3.2.1 Optical module design options with bifacial cells......Page 101 3.2.2 Light management in bifacial modules......Page 102 3.3 Electrical design and interconnect options with bifacial cells: half-cut cells, multi-busbar and multi-wire concepts......Page 104 3.3.1 Multi-busbar interconnection......Page 105 3.3.2 Half cells and smaller......Page 107 3.3.3 Shingles and other stacking options......Page 110 3.3.4 Interconnection of back-contact solar cells......Page 115 3.4 Characterisation of bifacial devices......Page 118 3.4.1 Bifacial I–V characterisation......Page 119 3.4.2 Imaging methods......Page 125 3.4.3 Outdoor measurements on single modules......Page 127 3.5.1 Electrical models......Page 129 3.5.2 Thermal behaviour......Page 130 3.6 Reliability and durability of bifacial modules......Page 132 3.6.1 Effect of higher output current......Page 133 3.6.2 Heat management......Page 135 3.6.3 Selection of module materials for bifacial modules......Page 136 3.6.4 Discussion on current IEC 61215 testing and its suitability for bifacial modules......Page 137 References......Page 138 4.1 Introduction/motivation......Page 144 4.2 Critical review of current status of bifacial simulations......Page 145 4.3 Bifacial gain simulation model......Page 148 4.3.1 Optical model......Page 149 4.3.2 Electrical model......Page 155 4.4.1 South-facing stand-alone bifacial module......Page 159 4.4.2 East-west-facing stand-alone vertical bifacial module......Page 163 4.4.3 Stand-alone bifacial module with horizontal single-axis tracking......Page 165 4.4.4 Bifacial module field......Page 167 4.4.5 Result validation......Page 170 4.6 Summary/outlook......Page 172 References......Page 174 5.1 Introduction......Page 178 5.1.1 Key indicators to analyze the potential advantage of a bifacial system over a monofacial one......Page 179 5.2 Overview about small scale bifacial systems with information concerning the bifacial gain......Page 180 5.2.1 Vertically installed bifacial systems......Page 201 5.3 Bifacial systems with non-standard mounting situation......Page 204 5.3.1 Vertically installed bifacial systems......Page 205 5.3.2 Floating bifacial PV......Page 213 5.4 Overview of large-scale bifacial systems and growth perspectives......Page 218 5.5 Horizontal single-axis tracked bifacial systems......Page 225 5.5.3 Fixed tilt and single-axis tracking of bifacial PERC+ modules by TRINA......Page 227 5.5.5 Tilted vertical single-axis tracking system with bifacial PERC+ by Solar World......Page 228 5.5.6 Summary of tracked bifacial PV systems......Page 229 5.6 What does bifacial gain tell us? How to transfer this to lowest LCOEs?......Page 230 5.6.1 Definition of bifacial gain......Page 231 5.6.2 Examples of bifacial gains: comparison of apples with apples......Page 233 5.6.3 Bifacial applications in reality: comparison of apples with oranges......Page 235 5.6.4 Summary......Page 236 5.7 Conclusion......Page 237 References......Page 239 6.1.2 Parameters involved in the calculation of the LCOE......Page 246 6.1.3 Risk management in bifacial PV systems......Page 249 6.2 Sensitivity study for LCOE of bifacial PV......Page 250 6.2.1 General assumptions and LCOE of monofacial PV......Page 251 6.2.2 LCOE of bifacial PV and monofacial PV: sensitivity study......Page 253 6.2.3 Sensitivity analysis: bifacial gain versus ground cover ratio and resulting LCOE......Page 256 6.2.4 Summary......Page 260 References......Page 261 7. Importance of bankability for market introduction of new PV technologies (Andre´ Richter)......Page 262 7.1 Value chain and cost types......Page 263 7.2 Measures to calculate PV systems......Page 270 7.3 Energy yield simulation......Page 273 7.4 Risk—the key factor in a project......Page 276 7.6 Guaranties and warranties......Page 285 7.7 Rating schemes......Page 287 References......Page 289 8.1 Introduction......Page 292 8.2 Some design rules (of thumb) for bifacial PV installations– as presented in the indicated sections of this chapter......Page 293 8.3.1 Albedo......Page 294 8.3.2 Latitude......Page 295 8.4.1 Single modules – ground clearance......Page 297 8.4.3 Spacing between cells......Page 299 8.5.1 Fixed-tilt systems—ground clearance......Page 300 8.5.2 Fixed-tilt systems—tilt angle......Page 301 8.5.4 Combined empirical formulae......Page 302 8.5.5 Global combined analysis—bifacial irradiance gain for fixed-tilt systems......Page 304 8.6 Single-axis tracking systems......Page 305 8.7.1 East-west–latitude effects......Page 306 8.8.1 Thermal effects......Page 311 8.8.2 Electrical effects......Page 312 8.9 Summary and outlook......Page 314 References......Page 315 9.1 Summary......Page 318 9.2.2 Predictions of new cell and module technologies......Page 320 9.2.3 Future of bifacial PV......Page 321 References......Page 322 Index......Page 324