RICE UNIVERSITY The Design and Performance of Building-Scale Distributed Energy Generation in Houston, TX by Roque Tomas Sanchez A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE Masters of Science APPROVED, THESIS COMMITTEE: ^feT) Pedro Alvarez, George RVBrown Professor, Chair Civil and Environmental Engineering Brent Houchens, Assistant Professor, Mechanical Engineering and Materials Science Daniel Cohan, Assistant Professor, Civil and Environmental Engineering Jim. Blackburn, Professor in the Practice of Environmental Law, Civil and Environmental ^'Engineering HOUSTON, TX APRIL 2010 UMI Number: 1485972 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMT Dissertation Publishing UMI 1485972 Copyright 2010 by ProQuest LLC. All rights reserved. This edition of the work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Copyright Roque Tomas Sanchez 2010 ABSTRACT The Design and Performance of Building-Scale Distributed Energy Generation in Houston, TX by Roque Tomas Sanchez The expansion of worldwide energy demands, coupled with the fragility of electricity distribution grids, has sparked interest in building-scale distributed solar energy production. To further research into the barriers and challenges of residential grid- intertied solar photovoltaic electrical production, the U. S. Department of Energy founded the U.S. DOE Solar Decathlon. Through the 2009 U.S. DOE Solar Decathlon, the challenges of solar PV design and system performance were explored for the affordable- housing market of Houston, TX. Energy demand and production modeling techniques were used to inform the design of the prototype, the Zero-Energy Row House (ZEROW), and techniques for cost reduction and simplification of power generation systems were employed in the pursuit of archiving grid-parity solar electrical production as the household level. Preliminary ZEROW system design, performance, and challenges are discussed, as well as directions for future research. Acknowledgements I would like to thank the faculty who supported the Rice Solar Decathlon project long before it began to bear results, including Pedro Alvarez, Dean Sallie Ann Keller, and Bart Sinclair. The incredibly-dedicated professors who guided the Rice Solar Decathlon team -Danny Samuels, Nonya Grenader, and Brent Houchens- gave invaluable time from their own projects, livelihoods, and research to help make this project reality; we would have not progressed very far without your insight. My co-investigators in the Rice Solar Decathlon, David Dewane, Architecture Lead, and Allison Elliott, Communications Lead, both endangered their sanity and academics to labor for three years on this project. We have more than one-hundred students and trade volunteers to thank for the completion of the ZEROW house, and I would like to thank Travis Martin, Naoki Nitta, Aron Yu, Willian Li, Cassie Lopez, Erin Morrison, Becca Sagastegui, Henry Neilson, Bandon Chalifoux and Jeremy Caves for their contributions to the ZEROW's engineering performance. Additionally, I would like to thank Christof Spieler, Chris Boyer, and John Gardner for their professional guidance. The contributions of Robert Cross, of Plumbers Local Union No. 68, and Gary Strouz and Jesse Faz, of IBEW Local Union 716 and the Houston Joint Apprenticeship & Training Committee, represent incredible professional dedication and a wealth of technical knowledge. I owe a large debt to my friends and family, as they have continuously supported me in my life and research. I send a special thanks to my family and Fiona Adams for helping me rise to the challenges of these past four years of life and research. Finally, my gratitude lies with the members of my thesis committee, who provided crucial guidance and feedback which shaped this thesis. Thank you all. Table of Contents 1.0 Introduction 1 2.0 Objectives 5 3.0 Materials and Methods 7 3.1 Photovoltaic Modules 7 3.2 Inverters 8 3.3 Solar Thermal System 11 3.4 Mounting Hardware 12 3.5 Data Collection and System Monitoring 14 3.6 Modeling 18 4.0 Construction 23 5.0 Evaluation 25 5.1 Energy Performance 25 5.2 Cost Performance 27 6.0 Conclusions and Suggestions for Further Research 30 List of Tables and Figures Figure 1: Cost of residential retail electricity in Texas 2 Figure 2: Enphase Enlighten production monitoring user 13 interface Figure 3: Section view of mounting hardware integration 15 Figure 4: Summary of contest load analysis 15 Figure 5: Summary of annual prototype electricity demands for 15 Houston, TX Figure 6: Stainless steel Z-clip 17 Figure 7: Photo of a portion of the competition team 17 Figure 8: Three-line diagram of solar PV system 19 Figure 9: Construction of ZEROW on the Rice University 20 Campus Figure 10: Roof deck with elevated steel angles spans exposed 20 Figure 11: View of sub-array of 8 PV modules 20 Figure 12: Delivery of ZEROW to National Mall 20 Figure 13: Solar PV production estimates from NREL's 22 PV Watts v2. Figure 14: Cumulative energy balance and global horizontal 22 insolation Table 1: Chronology of significant research events 4 Table 2: Inverter technology comparison 9 Table 3: NREL data collection 13 Table 4: Team competition prototype comparisons 24 Table 5: Detailed Construction Costs of Competition Prototype 26 ZEROW Table 6: ZEROW Lifetime Electrical Production Costs 26 1 1.0 Introduction Since the development of the modern photovoltaic cell by Bell Laboratories in 1955, researchers and engineers have sought to harness predictable solar insolation for society's energy demands [1]. While interest and funding of solar energy generation has fluctuated along with the the state of the global energy demand and politics, today there remains considerable interest in developing a solar energy infrastructure that is not only robust, but less environmentally-intensive than energy derived from fossil hydrocarbons. Globally, energy demand continues to rise, especially as less-developed nations begin to foster economies dependent on abundant energy supplies. Within the United States, the Energy Information Administration predicts that renewable energy, including solar, will continue to experience growth in the years leading up to 2030 [2]. Increased awareness of environmental concerns, especially global climate change, will undoubtedly continue to drive this development. For many energy users, interest in renewable energy is spurred by the potential for economic competitiveness. The cost of energy derived from fossil hydrocarbons is linked to the costs of extraction, processing, and transportation of those fuels. As fossil extractable hydrocarbon reserves are depleted, energy costs will continue to rise. In the case of Texas, the average cost of residential retail electricity increased from 7.20/kWh to 13.040/kWh between 1990 and 2008; during this period, price rose even in the face of the deregulation of the retail electricity market [3]. Distributed solar generation thus represents an investment in energy price stabilization to some electricity users. Additionally, as the externalities of hydrocarbons are priced, as in the example of the Retail Residential Electricity Cost in Texas, 1990-2008 16.00 14.00 R2 = 0.6944 12.00 r 10.00 5 "5 8.00 c a • Residential Retail Eletricity « 6.00 Cost (cents/kWh) — Linear (Residential Retail 4.00 Eletricity Cost (cents/kWh)) 2.00 0.00 1990 1995 2000 2005 2010 2015 2020 Year Figure 1: Cost of residential retail electricity in Texas [3] Source: U.S. Energy Information Administration. Annual Electric Power Industry Report. FormEIA-861 (2008). 3 European Union Emissions Trading Scheme, energy generation free from operational greenhouse gas emissions may continue to drive the economic adoption of solar generation. While photovoltaic materials research and product development are conducted by an array of interested parties, including universities, energy development firms, and U.S. national laboratories, cohesive research into the challenges of residential solar energy integration failed to attract significant funding through the 1990's. Without significant research into the barriers to the implementation of household-scale PV generation in the U.S., a gap exists between improving technology and its dissemination to intended end users. In 2002, the U.S Department of Energy (DOE) recognized the considerable potential of residential implementation research and founded the Solar Decathlon competition. In its design, the Solar Decathlon competition combines elements of educational outreach and distributed research. Through the competitions, teams composed of universities or university coalitions must design and build a house that derives the entirety of its operational energy from the the solar radiation incident on its site. Research teams are chosen through a competitive request-for-proposal process, and teams must model, design and build an entry house and transport it to the National Mall in Washington, D.C. for a final evaluation and exposition. The entries are subjected to a round of ten contests -the namesake decathlon- to approximate the demands placed on an average single-family residence. Ultimately, the Solar Decathlon represents