Utilities Hatch Ambitious Plans to Own and Operate Large-scale PV Projects  

REW has an article on Duke Energy's experiment in expanding distributed power generation using rooftop solar PV - Utilities Hatch Ambitious Plans to Own and Operate Large-scale PV Projects

In years past, solar photovoltaic (PV) installations were largely done in a piecemeal fashion, planned and implemented one rooftop or ground-mounted system at a time. But as solar technology has improved and as state governments demand more renewable generation through portfolio standards, large-scale projects are becoming more common. A growing number of utilities, rather than depend on independent power producers to build these projects, have launched multi-million dollar initiatives to own and operate their own solar assets.

Charlotte, N.C.,-based Duke Energy, one of the largest power companies in the United States and serving about 4 million customers, is one of them. In May, the utility received approval from the North Carolina Utilities Commission to proceed with a $50 million plan to install 10 megawatts worth of solar PV systems in the state, enough electricity to power 1,300 homes. The initial plan was double the size, but the North Carolina Utilities Commission Public Staff, which acts as a consumer advocate, asked for a reduction out of concern that the proposal was too aggressive and expensive.

Under the current plan, the solar systems, which will be owned and operated by the utility, will be installed starting later this year on the roofs and grounds of homes, schools, office buildings, warehouses, shopping malls and industrial plants. Between 100 and 400 separate arrays will be installed — the details are still being worked out — and they will range from about 2.5 kilowatts on residential rooftops to more than 1 megawatt (MW) on open land or on the rooftops of large commercial buildings. The power will be fed into the electrical grid and participants will be paid for use of their roofs or land, based on the size of the installation and amount of electricity generated at the site.

The main driver behind the project is North Carolina’s renewable portfolio standard, which requires the utility to satisfy 12.5 percent of its customers’ power needs with renewables or energy efficiency by 2021. The law requires that a growing portion of that renewable goal be met with solar energy, starting at 0.02 percent of the electricity sold by 2010 and rising to 0.2 percent by 2018.

But there are other reasons behind Duke’s decision to own and operate the facilities, according to Owen Smith, the utility’s managing director of renewable energy strategy. “We believe distributed generation will grow in prevalence as customers make these investments on their own,” Smith said. “We felt this was something we needed to get ahead of to understand the impact distributed generation would have on the grid.”

No single rooftop array on its own could disrupt Duke’s distribution network, but a large number concentrated in one area could lead to imbalances on a circuit, Smith said. By analyzing the data from the 10 MW project, the power company hopes to understand the limits of its electricity network and avoid potential problems. But distributed generation is also an opportunity for Duke, Smith said. With solar arrays strategically placed closer to the demand, the grid should become more robust, and the plan offers the power company a new way to interact with its customers, Smith said.