Growing Photovoltaic Gardens in Rural America – IEEE Smart Grid

Some of the more progressive electric cooperatives in the United States are helping their consumers overcome barriers to residential installation of photovoltaic arrays by building solar gardens, also known as community solar projects. Examples are found not just in the sunny Southwest but also in chilly and sometimes sun-starved upper northern states, as well.

For most consumers, if any solar power is available from their electric utility, it does not amount to much and it is bundled invisibly into their regular utility bills. Consumers who wish to deploy their own solar generation face daunting economic barriers: high initial investment costs, the difficulty of determining long-term costs and benefits, the complexities of tax deductions and credits, the challenge of obtaining grants and other incentives, and unpredictable maintenance charges. There are high physical barriers too: limited rooftop or land area, obstructive shading from vegetation and buildings, intrusive and sometimes unsightly modifications to buildings and facilities and the personal inconveniences of maintenance.

In recent years, however, some of the more progressive electric cooperatives are helping their consumers overcome such barriers by means of solar gardens, also known as community solar projects. They are constructing and operating centralized solar projects, arrays of photovoltaic cell panels that convert sunlight to electricity. Consumers can purchase a “garden plot” of panels outright or subscribe to output from the garden and obtain the same benefits as if the PV panels were operating on their own premises: They thereby reduce their metered energy consumption and can even “run the meter backwards” when their solar panel output exceeds their consumption.

Solar power is not actually physically transmitted from the PV arrays to the customer over the cooperative’s distribution lines. Instead, the cooperative makes a transactive energy transfer in which customer’s energy consumption is offset by their solar garden output, just as if the panels were operating on their own premises on their side of the utility’s meter. The amount of solar capacity that the consumer can purchase is limited so that it doesn’t actually provide more energy annually than the consumer uses.

Kit Carson Electric Cooperative serves almost 28,000 retail consumers in and around scenic Taos, New Mexico, where the sun shines nearly every day of the year and which is familiar to people the world over from famous photos by Ansel Adams and paintings by Georgia O’Keeffe. A dozen years ago the cooperative formed a voluntary committee of its consumers to look into renewable energy possibilities. After thoroughly investigating wind, solar and biomass alternatives, the committee concluded that solar power was the most promising.

With assistance from Los Alamos Energy Laboratory, the cooperative embarked on a series of solar projects, starting with one funded in part through a clean energy bond that it competed for and won. The project embraces four locations, each with capacity of 250 kilowatts. One of them satisfies essentially all of the electric energy requirements of the Taos campus of the University of New Mexico.

The solar committee reconvened in 2010 and decided the cooperative should aggressively support consumer-owned solar power by allowing net metering. The committee also found that most of the cooperative’s member consumers would not be able to overcome the many barriers to PV. There was consensus that it was important for the cooperative to make solar power available to consumers from all economic strata, not just the few capable of overcoming the economic and physical barriers. To that end, the cooperative began deploying and continues to develop solar gardens. The utility already has more than 1.5 MW of solar garden capacity, and there is more than one megawatt of consumer-owned solar power in the co-op’s operating area.

Kit Carson has succeeded in making the community solar projects not only increasingly ubiquitous and productive but also attractive and appreciated throughout the community. Some PV arrays, for example, provide shade for parking at schools and businesses with the same facilities that are turning solar energy into electricity. One actually powers the utility’s board and community meeting room. Some of the projects have even become tourist attractions.

Solar gardens are being created not only in the sunny Southwest but also in areas where sunlight is less plentiful and snow and ice are abundant. Wright-Hennepin Electric Cooperative is an electric distribution utility serving 47,000 retail customers in rural Minnesota northwest of Minneapolis. Like Kit Carson, it recognized that a growing number of its consumers were interested in renewable energy and that private companies were beginning to offer it to them. Yet most of their consumers could not overcome the many barriers to deployment.

Wright-Hennepin investigated renewable energy options and deployed pilot projects at its headquarters location. The first project was a 20-kW wind turbine in 2007; next came a 2-kW high performance photovoltaic array in 2009; and then, three years later, another 2-kW PV array backed by integrated battery storage. Based on data from those projects, the cooperative determined that wind power was not yet economically feasible because limited winds in the region coupled with the costs of deployment resulted in an extremely long payback period. However, solar power was more attractive.

The cooperative proceeded in 2012 to develop a centralized solar garden, an array of 171 PV modules, rated at 32.5 kW, with a storage facility consisting of four 9.2-kW battery units. The cooperative invited members to purchase “plots”and reap the produce. The first project was fully subscribed in just two months, with 17 households signing up, and the second one is already more than half subscribed even though construction has not yet started.

Wright-Hennepin was the first cooperative in Minnesota to offer this community solar option to its members, and the first one in the nation to incorporate electric battery storage in an innovative approach that provides demand response and reliability benefits to all of the utility’s consumers, not just the ones getting power from the solar garden. The cooperative is now researching fuel cells for a pilot project in the near future.

Both the Kit Carson and Wright-Hennepin cooperatives are committed to expanding their community solar activities. But they, too, face significant challenges. In the short run, for example, the output of the solar projects reduces revenues more than it reduces costs. Nevertheless, they have decided to “take the long view” of the importance of clean, renewable energy. They also recognize that if they do not provide a competitive solar power option to their consumers, other providers will.

What is more, they believe that increasing the amount of distributed solar power generation is a crucial hedge against rising costs of power from their traditional grid sources. And they see that distributed generation can improve reliability and ensure that not all consumers are totally without power during natural and man-made events that take the legacy centralized grid out of service.

In contrast to vertically integrated utilities, electric distribution cooperatives do not generate and transmit power; they buy power at wholesale and deliver it over their distribution lines to retail customers. Most are limited in how much solar power they can accept because of their contracts with the utilities that they purchase all of their power from. They are working with state and federal governments and their wholesale power suppliers to loosen those constraints.

Electric cooperatives’ small size and low population density limits their ability to finance and deploy solar gardens as rapidly as they would like. Electric cooperatives average about 20,000 consumers. And their members are usually widely dispersed with the average coop having 7 customers per mile of line. Investor-owned utilities average 30, public power systems average 50.

Cooperatives are finding it necessary to make their existing electric distribution grids smarter with more capabilities for monitoring, analysis and control to ensure that all of their customers are served safely, securely and reliably as the number of distributed generation and storage projects grows. After all, their distribution systems were originally designed for power to flow one way to consumers from a handful of centralized transmission lines.

As Kit Carson, Wright-Hennepin and other electric cooperatives meet these challenges, they are in the vanguard of utilities growing green power for their customers. And they are doing so with groundbreaking transactive energy arrangements. They are at the leading edge of a modern, intelligent grid for the 21st century.

Growing Photovoltaic Gardens in Rural America – IEEE Smart Grid.