Tucson Electric Power Company (TEP), headquartered in Tucson, AZ, currently has nearly 5Á0 MWdc of utility-scale grid-connected photovoltaic (PV) systems installed in its service territory. These systems have been installed through a multiyear, pay-as-you-go development of renewable energy, with kWhac energy production as a key program measurement. This PV capacity includes a total of 26 crystalline silicon collector systems, each rated at 135 kWdc for a total of 3Á51 MWdc, that have been installed at the Springerville, AZ generating plant by TEP making this one of the largest PV plants in the world. This facility started operations in 2001 and recently passed the 5-year milestone of continuous operations. These systems were installed in a standardized, cookie-cutter approach whereby each uses the same array field design, mounting hardware, electrical interconnection, and inverter unit. This approach has allowed TEP to achieve a total installed system cost of $5Á40/Wdc and a TEP-calculated levelized energy cost of $0Á062/kWhac for PV electrical generation. This paper presents an assessment of operating experience including performance, costs, maintenance, and plant operation over this 5-year period making this one of the most detailed and complete databases of utility-scale PV systems available to the US DOE Program.

Arizona Public Service (APS) currently has over 4Á9 MW dc of grid-connected photovoltaic systems that have been installed in its service territory over the past five years. Most of this installed PV capacity is in support of the Arizona Corporation Commission Environmental Portfolio Standard goal that encourages APS to generate 1Á1% of its energy generation through renewable resources by 2007, with 60% of that amount from solar. During this time, much has been learned regarding performance, cost, maintenance, installation and design. This paper presents an assessment of these topics and a perspective associated with this PV experience.

The field performance of photovoltaic systems has been studied extensively for many applications and a number of databases exist in the United States and internationally. However, these databases focus almost exclusively on the system elecrical performance. Published information on the operation and maintenance (O&M) experience and costs for photovoltaic systems is almost nonexistent. At a time when photovoltaics is being considered as a viable option for distributed energy generation, it is critical that maintenance experience be captured to identify lifecycle costs and/or levelized energy costs for these systems, as well as to identify areas for system and component improvements. This paper addresses the data collection, analysis and results of an offgrid residential customer service program offered by the Arizona Public Service (APS) Company over a six-year period from 1997 through 2002. Standardized, packaged photovoltaic systems were offered and operated by APS through a lease arrangement with customers throughout the state of Arizona. The operation and maintenance records for these systems were carefully tracked and analyzed. The O&M costs, database development, cost drivers, lifecycle cost implications, and lessons learned are presented and discussed. Published in 2004 by John Wiley & Sons, Ltd.key words: photovoltaic systems; operation and maintenance; off-grid residential; utility photovoltaics; database; field experience INTRODUCTION R eductions in the manufacturing costs of photovoltaic (PV) modules 1 coupled with improvements in the balance-of-system hardware 2 have made PV systems an increasingly viable alternate energy option for a variety of applications. 3 Electrical field performance of a number of installed systems has been examined extensively and performance databases 4-6 have been developed. However, as PV attempts to expand into potential markets, questions regarding PV system lifecycle cost (LCC) are bringing a renewed interest in the operation and maintenance (O&M) experience and cost from installed systems. A recent study 7 of grid-tied and stand-alone systems installed throughout the United States over the period [1995][1996][1997][1998][1999][2000][2001][2002] concludes that 50% of the systems were installed improperly, having deficiencies in safety, durability, and/or performance. The impact Contract/grant sponsor: US DOE National Nuclear Security Administration; contract grant number: DE-AC04-94AL85000. Applicationsof these deficiencies on the long-term viability of PV systems is yet another compelling reason to gather and analyze O&M data. Unfortunately, published information on O&M field experience and cost is nearly nonexistent. Why is this information so important? Compiling and analyzing field maintenance events (component and system reliability, scheduled and unscheduled maintenance) are invaluable both from a business and from an engineering standpoint. On the business side, it enables the determination of the LCC for PV systems. The O&M costs coupled with the initial system c...

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Tucson Electric Power Company (TEP) currently has nearly 5.0 MWdc of utility-scale grid-connected photovoltaic (PV) systems that have been installed in its service territory since 2000. Most of this installed PV capacity is in support of the Arizona Corporation Commission Environmental Portfolio Standard (EPS) goal that encourages TEP to generate 1.1% of its energy generation through renewable resources by 2007, with 60% of that amount from photovoltaics. The EPS program provides for multi-year, pay-as-you-go development of renewable energy, with kWhac energy production as a key program measurement. A total of 26 crystalline silicon collector systems, each rated at 135 kWdc, have been installed at the Springerville, AZ generating plant by TEP making this one of the largest PV plants in the world. These systems were installed in a standardized, cookie-cutter approach whereby each uses the same array field design, mounting hardware, electrical interconnection, and inverter unit. This approach has allowed TEP to achieve a total installed system cost of $5.40/Wdc and a TEP-calculated levelized energy cost of $0.10/kWhac for PV electrical generation. During this time, much has been learned regarding performance, cost, maintenance, installation and design. This paper presents an assessment of these topics and a perspective associated with this PV experience.

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This paper presents alternative approaches for reducing the costs of roof-mounted, grid-connected photovoltaic (PV) systems. Six cost reduction approaches are presented, together with examples, data and information from Florida and other states. Finally, the paper identifies these areas on which efforts should be focused to achieve the 2020 cost goals established by the U.S. photovoltaic industry.

Tucson Electric Power Company (TEP) is a U.S. utility leader in the early adoption of photovoltaic power generation with over 6.0 MWdc of grid-connected photovoltaic (PV) systems installed in its service territory since 2000. A signifi cant element of the TEP photovoltaic effort is the SunShare PV hardware buy-down program that has been offered to TEP customers since 2001. During the past fi ve years, 282 residentialsize systems totaling 655 kWdc of crystalline silicon collectors have been installed in the Tucson area through SunShare. Much has been learned regarding performance, cost, maintenance, installation, and design of these systems. This article presents an assessment of these topics and a perspective associated with a family of systems within this PV program.