On the rooftops, and dotting the landscapes of residences across United Cooperative Services’ territory, more and more shiny black solar panels bathe in the sunlight.
As homeowners go about their daily lives, the sunlight hitting those dark black panels will start exciting electrons that eventually turn into energy used to power appliances, lights and TVs within the household. Where windmills once commanded attention as the countryside’s working standard for renewable energy resources; these small, localized generating sources are becoming a more common application within United’s service territory. Known in the electric industry as distributed generation (DG), they are slowly transforming the future of the power industry.
DG is defined as a power source interconnected to a utility’s distribution system. It generally refers to small-scale generation sources located near the point of end use. Common DG systems are solar, wind, landfill gas, diesel-fueled engines, and natural gas-fueled micro-turbines. In United’s territory, the most common form of DG is solar.
Better technology, federal tax incentives and reduced manufacturing costs have caused solar applications to become more popular in recent years. Of United’s 171 member-owned interconnected DG systems, 128 are solar arrays.
While the first system interconnected with United was installed in 2000, 54 percent of the total interconnected DG systems on United’s distribution lines were installed after January 2014, and 28 percent of the total systems were recently installed within the last year and a half.
“The vast majority of the recent DG applications have been solar,” said Jameson Parker, one of United’s professional engineers. “United has received only two wind turbine applications since January 2014. In our area, solar tends to be a more reliable energy source on a residential level. We validated this over the years through the data we obtained from DG learning labs located at our area offices.”
In 2010, United made it an objective to install both solar and wind (where possible) at all the cooperative’s offices. United currently has nine solar arrays and four wind generators, and each system varies by technology and size. The siting of these installations goes beyond benefits of reducing the load at each facility. United wanted to fully understand the technology and how the systems work so the cooperative’s energy experts could assist members in their efforts to bring DG to their homes.
“We take a lot of pride in being our members’ trusted energy advisor,” United Vice President of Power Supply Blake Beavers said. “The learning labs are one example of the lengths the cooperative goes to in assisting members reach their energy innovation goals. The learning labs allow members to obtain near real-time production data, understand component requirements and determine true payback periods for these applications based on those production numbers.”
With an increase in the number of DG systems interconnecting with United’s distribution system, more members are being exposed to the technology and are being approached by third-party installers. As the membership’s trusted energy advisor, United is committed to keeping members informed about the potential effect the investment could have on their monthly bill. To help with that effort, United has identified five main components that each member needs to embrace before purchasing a DG system.
First, before considering whether to invest in a DG system, it is important for a member to know their usage habits and consumption levels. One of the many tools in United’s Energy Innovation toolbox is the free energy audit that is available to all members. During the audit, one of United’s energy experts will evaluate the member’s usage and provide recommendations on how to become more efficient. United has always been an advocate of conservation and energy efficiency, and believes it should be the first step in reducing consumption. Reducing load through efficiency could determine the appropriate size of a DG system, which reduces the initial cost of the investment.
Second, it is important to fully understand United’s rate structure and buy-back policies for DG accounts. The rate structure will affect the overall impact a DG system will have on a monthly basis, which affects the overall return on the investment. The rate structure for DG accounts will also be an important factor to consider when properly sizing a system. According to United’s DG policy, systems under 50kW will be billed on what is called a “net-metering” rate. Net metering is a measurement and billing mechanism that allows members to receive credit for the surplus power that is not consumed on the premises and flows back onto United’s distribution system.
To take advantage of net-metering on a DG system, United will replace the member’s current meter with a special meter that records energy delivered from United’s distribution system to the member. The meter has a separate register that tracks the surplus energy generated by the DG system that was not consumed on site. At the end of each billing period, United will take the amount of energy that was “delivered” to the member, and the amount of surplus energy that was “received” from the member, and net the two readings. The member then will be billed on the net difference between the delivered and received readings. When a member produces more energy than they consume on a monthly basis, United will buy back the excess energy at United’s buy-back rate, which currently is $.0637 per kWh. This is the cost of wholesale power that United purchases from its power supplier, Brazos Electric Power Cooperative, without markup. Members should be aware that United has invested in the infrastructure that allows for net-metering to function over the cooperative’s system, so the cooperative charges a $25 minimum bill each month (the same minimum for every residential member) to recover some of the costs associated with providing power to the residence when the DG system is not generating energy (sun is not shining, or wind is not blowing). Any overproduction credit does not negate this minimum monthly charge.
Third, having a site that is less than ideal can prevent a system from generating at its rated capacity. While there are many things to consider when designing and installing a solar DG system, shade can naturally negate optimal performance,” said Parker. “It’s important to construct systems in an area that will receive the maximum amount of daylight, both during the winter and the summer months.”
Evaluating the orientation (the direction) the system will face is another important consideration when a system is installed on a roof or at another fixed and stationary site. In general, the best orientation for a solar module in the Northern Hemisphere is true south. However, solar arrays can face directly east or directly west of true south without significantly decreasing their performance. Systems that favor a more northern orientation (anything above directly east and west) will produce less than optimal performance results.
Fourth, when determining size, it is important for a member to first determine the goal or reason for investing in a DG system. Is it to reduce the monthly usage by a certain percentage, or is it to realize the quickest return on investment? Once the goal is defined, United can help the member size a system to meet the goal. United energy experts have multiple tools that can aid members in assessing how a specific system size can affect the end result. One of the tools commonly used by United energy experts is the National Renewable Energy Laboratory’s (NREL) PV Watts calculator. The online calculator is a free, user-friendly tool that provides monthly generation estimates according to system size and location.
Fifth, United has developed a 10-step process to obtain interconnection. These steps were developed to simplify planning and installation, and to provide guidelines for the member or the third-party contractor hired by the member. To ensure a member has made all the proper arrangements for interconnection on the cooperative’s distribution system, United recommends following the provided guidelines.
United energy experts understand solar and wind DG systems can be intimidating and complex, but as the membership’s trusted energy advisor, the co-op’s staff serves as a reliable resource for navigating questions and concerns from the education phase all the way through to the interconnection phase.
