Photovoltaic Power Plant Experience at Tucson Electric Power

Abstract

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.

Five years of operating experience at a large, utility‐scale photovoltaic generating plant

“…Interestingly, the Springerville energy cost figure-of-merit for fixed flat-plate systems is nearly identical to the energy cost figure-of-merit reported for one-axis, tracking horizontal flat-plate systems installed at Prescott, AZ. 2 It is also interesting to note the significant energy cost figure-of-merit difference between the utility-scale Springerville systems and residential systems. A total of 82 SunShare residential systems have been installed in the TEP service territory during the past few years and are being tracked by TEP and Sandia for performance, cost, and maintenance experience.…”

“…1 The TEP systems incorporate standardized, fixed arrays. 2 The 5 years of TEP operating experience with these systems, including performance, cost, maintenance, installation, and design is the topic of this paper.…”

The character of power output from utility‐scale photovoltaic systems

“…3 Monthly averages of real power output data from large-scale PV power plants have been published. 4,5 Here, we present analyses of real power output data with 10 s and 1 min resolution from a single 4 MW site and data with 10 min resolution from three $100 kW sites. The power spectral density (PSD) of the output of large-scale PV can provide insight into the character of both cyclic (daily and seasonal) and non-cyclic (weather-related) fluctuations associated with array output.…”

9.4.1 Risk Analysis of Solar Photovoltaic Systems

“…Hardware risks include failures due to component malfunction or external events such as lightning or dust. The frequency of failures of PV system hardware such as data acquisition systems, junction boxes, PV modules, and general failures due to lightning strikes was based on a report of TEP's experience with the Springerville Generating Station [Moore et al, 2010]. Severity for hardware failures went from simple system restarts to complex maintenance procedures [Moore et al, 2010].…”