Question: What cities are the headquarters for the company that owns Avra Valley Solar Generating Station?

full_context: Document 1: Avra Valley: The Avra Valley is a 50-mile (80 km) long northwest-southeast valley, bordering the west of Tucson, Arizona. The Tucson Mountains are at the valley's center-east, with suburbs ranging east of the Tucson Mountains and trending northwest to the Avra Valley's northeast. This entire northwest stretch from Tucson contains the northwest trending Interstate 10, the route to Casa Grande and Phoenix. The northeast of the valley contains Marana on I-10, the Pinal Airpark, an aircraft storage park, and other communities along I-10. Avra Valley Airport is a general aviation airport in Marana, located about 15 miles (24 km) northwest of Tucson and being used for storage of classic propeller-era airliners.
Document 2: Avra Valley Solar Generating Station: The Avra Valley Solar Generating Station is a 34 MW (DC, 25 MW AC) photovoltaic power plant in Avra Valley, Pima County, Arizona, owned by NRG. It uses single axis tracking that is designed to be maintenance free over the twenty year design life of the system. The panels are mounted on a north-south axis and rotate each day to follow the sun from sunrise to sunset, increasing the output by about 20%. Power is being sold to Tucson Electric Power in a 20-year power purchase agreement.
Document 3: Amonix: Amonix, Inc. is a solar power system developer based in Seal Beach, California. The company manufactures concentrator photovoltaic (CPV) products designed for installation in sunny and dry climates. CPV products convert sunlight into electrical energy in the same way that conventional solar photovoltaic technology does, except that they use optics to focus the solar radiation before the light is absorbed by solar cells. According to a comparative study of energy production of solar technologies, CPV systems require no water for energy production and produce more energy per megawatt (MW) installed than traditional PV systems. Amonix has nearly 70 Megawatts(DC) of CPV solar power systems deployed globally, including Southwestern U.S. and Spain. In May 2012, the Alamosa Solar Generating project, owned and operated by Cogentrix Energy, began commercial operation. This is the largest CPV power plant in the world and is expected to produce enough clean renewable energy per year to power more than 6,500 homes and will avoid the emissions of over 43,000 metric tons of carbon dioxide per year. The Alamosa Solar Generating Project is supported by a power purchase agreement (PPA), which is a long-term agreement to sell the power it will generate. Under the project’s PPA, the Public Service Company of Colorado will buy the power generated by the solar facility for the next 20 years. In July 2012, Amonix set the world record for photovoltaic module efficiency at 33.5% (full regression analysis) under nominal operating conditions, verified by the National Renewable Energy Laboratory. In April 2013, Amonix broke the record set in July 2012, demonstrating photovoltaic module efficiency at 34.9% (full regression analysis) under normal concentrator standard operating conditions (CSOC), also verified by the National Renewable Energy Laboratory. In August 2013, Amonix announced it had achieved a 35.9% photovoltaic module efficiency rating under concentrator standard test conditions (CSTC) as calculated by NREL. In June, 2014, the assets of Amonix were acquired by Arzon Solar, LLC for the purpose of continued development of CPV technology and products.
Document 4: Xcel Energy: Xcel Energy Inc. is a utility holding company based in Minneapolis, Minnesota, serving more than 3.3 million electric customers and 1.8 million natural gas customers in Minnesota, Michigan, Wisconsin, North Dakota, South Dakota, Colorado, Texas and New Mexico. It consists of four operating subsidiaries: Northern States Power-Minnesota, Northern States Power-Wisconsin, Public Service Company of Colorado, and Southwestern Public Service Co.
Document 5: NRG Energy: NRG Energy, Inc. is a large American energy company, dual-headquartered in West Windsor Township, New Jersey, and Houston, Texas. It was formerly the wholesale arm of Xcel Energy, and was spun off in bankruptcy in 2004.
Document 6: Energy Future Holdings: Energy Future Holdings Corporation is an electric utility company headquartered in Energy Plaza in Downtown Dallas, Texas, United States. From 1998 to 2007, the company was known as TXU Corporation until its $45 billion leveraged buyout by Kohlberg Kravis Roberts, Texas Pacific Group and Goldman Sachs Capital Partners. That purchase was the largest leveraged buyout in history. s of February 2013 , the company has been described as "struggling" which resulted in the April 29, 2014 filing for bankruptcy protection under Title 11 of the United States Bankruptcy Code.
Document 7: Enron: Enron Corporation was an American energy, commodities, and services company based in Houston, Texas. It was founded in 1985 as the result of a merger between Houston Natural Gas and InterNorth, both relatively small regional companies. Before its bankruptcy on December 2, 2001, Enron employed approximately 20,000 staff and was one of the world's major electricity, natural gas, communications and pulp and paper companies, with claimed revenues of nearly $101 billion during 2000. "Fortune" named Enron "America's Most Innovative Company" for six consecutive years.
Document 8: Beneixama photovoltaic power plant: Beneixama photovoltaic power plant is a 20 MW photovoltaic power plant located in Beneixama, Spain. The plant consists of approximately 100,000 solar panels, encompassing an area of approximately 500,000 m. The panels are City Solar PQ 200 modules made of polycrystalline silicon solar cells.
Document 9: Navajo Generating Station: Navajo Generating Station is a 2250 megawatt net coal-fired powerplant located on the Navajo Indian Reservation, near Page, Arizona United States. This plant provides electrical power to customers in Arizona, Nevada, and California. It also provides the power for pumping Colorado River water for the Central Arizona Project, supplying about 1.5 million acre feet (1.85 km) of water annually to central and southern Arizona. As of 2017 permission to operate as a conventional coal-fired plant is anticipated until 2017-2019, and to December 22, 2044 if extended. However, in 2017, the utility operators of the power station voted to close the facility when the lease expires in 2019.
Document 10: SUNGEN International Limited: SUNGEN International Limited is a subsidiary of Anwell Technologies Limited, with trading and manufacturing business in solar photovoltaics panels and modules. SUNGEN has a thin film solar module production facility in Henan, China using Anwell Solar’s manufacturing technologies. The facility will be used to produce 1.1 by 1.4 meter a-Si thin film photovoltaic modules, at an initial annual capacity of 40MW in 2010. In March 2010, the Group announced the mass production of thin film solar modules at SUNGEN’s manufacturing base in Henan of China using Anwell Solar’s thin film solar module production line.
Document 11: Solar power in Nevada: Solar power in Nevada has been growing, due to a Renewable Portfolio Standard which requires 20% renewable energy by 2015, and 5% from solar power. Nevada, at the end of 2007, became home to then-largest photovoltaic power plant in the world, the 14.2 megawatt (peak) Nellis Solar Power Plant, which, by selling the renewable energy credits (RECs), was able to provide Nellis Air Force Base with electricity for only 2.2 cents/kWh, compared to the 9 cents they are paying Nevada Power. Since then many larger solar power stations have been built in Nevada, with more proposed.
Document 12: Alamosa photovoltaic power plant: Alamosa photovoltaic power plant, is an 8.22 MWp photovoltaic power plant located in San Luis Valley, Colorado, USA. The power plant was developed by SunEdison, sells all output to Xcel Energy, and was completed in December 2007.
Document 13: Eversource Energy: Eversource Energy (formerly known as Northeast Utilities) is a publicly traded, Fortune 500 energy company headquartered in Hartford, Connecticut and Boston, Massachusetts, with several regulated subsidiaries offering retail electricity and natural gas service to more than 3.6 million customers in Connecticut, Massachusetts and New Hampshire.
Document 14: Exelon: Exelon Corporation is an American Fortune 100 energy company headquartered in Chicago, Illinois. It generates revenues of approximately $34.5 billion and employs approximately 34,000 people. Exelon is the largest electric holding company in the United States by revenue, the largest regulated utility in the United States with approximately 10 million customers, and is also the largest operator of nuclear power plants in the United States. It was created in October 2000 by the merger of PECO Energy Company and Unicom, of Philadelphia and Chicago respectively. Unicom owned Commonwealth Edison. Exelon operates regulated utilities in Illinois, Pennsylvania, Maryland, Delaware, New Jersey, and Washington, DC. In October 2009, Exelon had full or majority ownership of 17 nuclear reactors in 10 nuclear power plants. Exelon has operations and business activities in 47 states, the District of Columbia and Canada and is the largest competitive U.S. power generator with approximately 35,000 megawatts of owned capacity. Exelon merged with Constellation Energy Group in March 2012 and acquired Pepco Holdings in March 2016. Exelon consists of eight main operating subsidiaries with Exelon Generation, a deregulated energy generator, Constellation, a deregulated competitive energy supplier, and six regulated utilities, Commonwealth Edison (Illinois), Philadelphia Electric Company (Pennsylvania), Baltimore Gas and Electric (Maryland), Delmarva Power & Light (Delaware and Maryland), Atlantic City Electric (New Jersey), and Potomac Electric Power Company (Washington, DC and Maryland).
Document 15: Newark Energy Center: The Newark Energy Center is a 655-megawatt gas fired power plant in Newark, New Jersey. Approved in 2011, with construction beginning in 2012 it began commercial operations in May 2015. It is situated on a 23 acre brownfield east of Doremus Avenue next to a Hess oil terminal on the Passaic River. It was originally built as a joint venture between Hess Corporation and Energy Investors Fund, and it was taken over the latter in 2014.
ground_truth: West Windsor Township, New Jersey, and Houston, Texas