By interconnecting to wind farms and photovoltaic (PV) installations, electric utilities are able to provide a renewable alternative to their customers. In Texas, one utility company began studying renewable systems in anticipation of members' interest in the technology. Because these systems were becoming a more prevalent commodity, Guadalupe Valley Electric Cooperative (GVEC) installed them in various locations and began monitoring production.

GVEC formed GVEC Home in 1997 to sell, install and service energy-efficient appliances and HVAC equipment. Recently, the company also began offering consultations, installations and maintenance for small-scale renewable energy systems.

Training the Technicians

GVEC sent the technicians and the renewable energy advisor to Arizona to receive training direct from the manufacturer. During this week-long training session, the technicians learned how to properly install and tune the wind turbines and troubleshoot the units.

The course included hands-on and classroom work. During the field work, they learned how to level the foundation for the towers prior to installation. They also studied the interoperability of the wind units, how they function, and what kind of monitoring system is available to manage the turbine's output. At the end of the course, the technicians became certified installers and were ready to begin interacting one-on-one with the customers.

For the last few years, the company's renewable energy advisor has worked with members of the cooperative to sign a contract, procure the material, and then coordinate installation with the operations department. Because the technicians and team fully understand the technology, they are able to answer questions and help their customers with the renewable energy decision process.

Installing the Wind Turbines

The technicians install the 2.4-kW wind turbines using a bucket truck at the customer's location. Most of these units generate, on average, about 200 to 300 kWh per month. The wind turbines typically cost about $18,500, but GVEC offers its customers a rebate for $1 a watt or $2,400 upfront. This brings the installation cost down to $16,100, but customers can apply for a tax credit after it has been installed. Typically, the wind turbines also save customers between $20 and $30 per month.

When the crew members arrive on site, they first work on the foundation and drill a pilot hole. They then insert the rebar cage and lay out the foundation bolts in a pattern that aligns with the bolt plate on the tower. Next, they prepare the forms, attach ground wire to the bottom of the rebar cage, pour the concrete and let it cure for 21 days. Finally, they prepare to mount the form boards to the wind turbine once installed.

Once the curing process is complete, the technicians return to the customer's location to erect the wind turbine. They first assemble the tower on the ground and then attach the Nacelle, which houses all the turbine's generating components, to the tower. They then hook a wench and hoist the wind turbine up into the air. Once the wind turbine is in an upright position, the installation crew tightens bolts on the foundation. Using a torque wrench, they then ensure the wind turbine is level and functioning properly.

The wind turbines stand about 45 ft tall, and the rotor diameter is 12 ft. The Nacelle weighs about 200 lb alone, which doesn't include the tower or the blades.

The technicians typically can tie right into the customer's main circuit panel. The inverter is located in the Nacelle, so the power coming down the tower is alternating current (AC). As a result, the technicians don't need to find a location for an inverter at the ground level. Each unit has a pedestal a few feet from the tower, which has a production meter and an AC disconnect switch that runs to a subpanel and a 30-A breaker. The technicians install a monitoring meter so they can provide the turbines' true production numbers to other members within the service territory.

When siting the wind turbines, the crews need to make sure that the customer has adequate space. For every vertical foot, the unit needs to be a 1.5 ft away from the property line. The wind turbines also need to be located 200 ft away from any object more than 20 ft tall to ensure straight line wind with no turbulence for more efficient wind energy.

Standard maintenance on the units often includes releveling the units. The winter's strong northern wind can lean the units to the south, and they must be tilted back to the north. In addition, some units have had issues with lightning strikes and hail damage. Using bucket trucks, the installers can lower the wind turbines to adjust blades, troubleshoot the turbine or relevel the tower. At times, they will ask linemen for assistance if they are working in the immediate area.

Providing a Solar Solution

While GVEC's crew has installed six wind turbines for residential clients and three for GVEC offices over the last three years, PV has proven to be an even more reliable green source of energy. After monitoring the production of the PV system, the cooperative has discovered that in south Texas, which averages 300 days a year of clear sky and sunlight, solar appears to be more viable than wind.

Currently, GVEC has 304 renewable accounts, and solar makes up about 274 of those accounts. Of the 1.5 MW of renewable generation systems, solar comprises about 1.2 MW. One reason for the increase in the number of solar projects is the 20% to 25% drop in the cost of PV over the last two years. GVEC also offers a rebate of $2 per watt (up to $8,000) for systems under 20 kW, and solar qualifies for a 30% tax credit.

Currently, GVEC Home is focusing on the residential solar market and is responsible for selling and customer relations. GVEC Home partnered with a contractor called Solar Community to order the equipment and install the systems.

GVEC Home works with the customers on scheduling and coordinating the installation, creating the design and submitting it for approval.

GVEC Home helps the customer understand their actual past year of energy usage and also the approximate monthly production of the PV system. The renewable energy team uses a free online service called the PVWatts calculator to estimate the production using information such as the system's location and past historical weather data. GVEC Home can then show the member what percentage of their bill will be offset by the system as well as the proposed return on investment.

The company also has installed monitoring meters on the majority of the installations throughout its service territory. That way, GVEC Home can give honest feedback to potential customers about the units' energy efficiency based on actual data.

Creating a PV Array

GVEC Home schedules a site survey, and then works with the member of the cooperative to sign the agreement. Several factors are taken into account during this process. For example, the renewable energy advisor examines the members' main panel to make sure they have adequate space for the tie-in. In addition, he surveys the roof to take measurements and look for obstructions such as vent stacks or chimneys.

PV systems can be installed on a roof with an angel of 10 degrees to 35 degrees, with 30 degrees being ideal. The orientation of the roof needs to be between 90 degrees and 270 degrees, but 180 degrees is the most efficient. However, if the member's roof idle is at one of the extreme ends of the range, GVEC Home explains how it will affect their energy production. For example, systems that face an eastern direction will turn on earlier but shut off earlier. Ideally, GVEC Home wants the systems to have a minimum of six hours of production per day.

The last step is a shade analysis. For this process, GVEC Home uses a Solar Pathfinder tool that shows what tall objects such as trees will cast shadows throughout the year. Finally, GVEC designs the system and the array layout using the measurements and other information gathered from the site survey. The installers can design the photovoltaic system as a roof-mount, ground-mount, or pole-mount system.

The units are tied below the meter in the members' panel. Each unit has a safety mechanism in the inverter so that if the utility's power is not available, the units don't generate power. This eliminates all chances of backfeed on the line.

By offering both wind and solar solutions, GVEC is helping its members to offset energy costs and power their homes and businesses with renewable energy. The wind turbines and PV arrays are designed to provide maximum energy output while helping GVEC's members to go green.


Bobby Christmas (bchristmas@gvec.org) is the engineering and operations manager and COO for GVEC in Seguin, Texas. He is responsible for NERC compliance and oversees all the engineering operations for distribution, substation and transmission.

Sean Alvarez (salvarez@gvec.org) is the manager of business development and planning, and oversees all of the renewable energy projects for GVEC. He manages two sub businesses: one serves 6,000 Internet customers and the other manages retail sales of home appliances and HVAC systems. He also works on the wholesale power issues for the utility.

Blake Beavers (bbeavers@gvec.org) is a renewable energy advisor for GVEC, responsible for sales, consulting and installation of renewable products as well as interconnection.

Tips on Successful Renewable Installations

From its years of experience, GVEC has learned a few tricks of the trade. Here are some tried-and-true techniques to keep in mind when installing wind and photovoltaic installations to increase customer satisfaction and boost energy efficiency and production.

  1. Research the products
  2. Train your workforce
  3. Test products at the local office
  4. Collect data from test sites and share with your membership
  5. Educate your members or utility customers about renewable energy
  6. Create an interconnection agreement
  7. Develop a renewable energy program that makes interconnection less intimidating to your members or customers
  8. Educate employees to answer questions from your members and clients

Companies mentioned:

Guadalupe Valley Electric Cooperative | www.gvec.org

Solar Community | www.solarcommunity.com

Solar Pathfinder | www.solarpathfinder.com

Southwest Wind Power | www.windenergy.com

WindStream | www.windstream-inc.com