Case Studies and Projects
Earth Tools Installs 12.2 KW Solar PV Array in Owen County
On September 17, 2011, long-time ASPI supporter Joel DuFour started producing power from a 12.2 KW solar photovoltaic array mounted on the roof of his business’ main building. Joel’s business, Earth Tools, Inc. in Owen County, Kentucky, sells and services walk behind tractors and hand tools. In May of 2011, ASPI’s Andy McDonald provided a solar site assessment for Earth Tools and began working with them to design a solar PV system that would meet their needs. Andy helped Joel identify strategies for reducing their energy demands and becoming more energy efficient, which reduced the cost of the PV system. He also helped him apply for a REAP grant from the US Department of Agriculture, with the assistance of Jason Delambre of Interdependent Energies. Earth Tools was awarded the REAP grant in June, covering 25% of the project cost.
Earth Tools hired Sam Avery of Avery and Sun to install the solar PV system. Avery completed the installation in three days with a crew of six people. Earth Tools now hosts the largest solar PV system in Owen County and the second net metered PV system in Owen Electric Cooperative’s territory. Owen Electric’s CEO Mark Stallons came out to see the installation first-hand as soon as the system went online and was impressed with the system and the quality of the installation. Andy and Mark Stallons both serve on East Kentucky Power Cooperative’s Demand Side Management/Renewable Energy Collaborative, so their meeting at Earth Tools was an opportunity to further explore EKPC’s renewable energy options.
Earth Tools expects to generate over 15,000 kWh each year from their solar PV array. They have more energy-saving projects lined up and their goal is to meet 100% of their annual electricity needs with the solar PV system. The USDA REAP grant program is a competitive program that provides grants and guaranteed loans to rural small businesses and farmers for renewable energy and energy efficiency projects. To learn more, visit http://www.rurdev.usda.gov/or/reapee.htm or call Scott Maas at the USDA Rural Development office at 859-224-7435.
Housing Authority of Owensboro Installs Solar Water Heating Systems on 17 Buildings, Serving 68 Apartments
In 2011 the Housing Authority of Owensboro, Kentucky (HAO) completed installation of 17 solar water heating systems at Adams Village, a community that provides housing to about 80 elderly residents. Adams Village consists of 19 single-story, ranch-style apartment buildings, each containing four apartments. In 2009, the HAO contacted Andy McDonald of the Kentucky Solar Partnership for assistance evaluating their options for using solar energy on the HAO properties. After reviewing their properties and performing a detailed solar site assessment of Adams Village, the HAO decided to install solar water heating systems on 17 of the 19 apartment buildings at Adams Village.
Each of the 19 apartment buildings at Adams Village has a similar floor plan, with the apartments lined up in a row and all buildings generally facing south. Each building had previously been served by a single natural gas water heater, located in a closet on the back of each building. There is generally one elderly resident per apartment (although there are a few couples in the community). This arrangement provided a good opportunity for employing a solar water heating system, as we estimated a daily hot water load of 60 – 80 gallons per day for the entire building and were able to serve four apartments with each solar hot water system.
During the solar site assessment we evaluated the solar access and shading on the roofs of all 19 buildings. Despite the fact that there are many mature trees throughout Adams Village, we found only two buildings where shading prohibited the use of solar water heaters.
Since the buildings already had natural gas available we decided to use gas-fired tankless water heaters for back-up water heating. The back-up water heaters were needed to ensure residents had hot water at all times, even during extended cloudy weather in the winter. Each unit includes two Takagi TK-3 tankless water heaters and an 80 gallon solar storage tank. The Takagi’s are supplied by the hot water coming from the solar storage tank and are programmed to only turn on when the incoming water is below 120oF. We chose the Takagi’s in part because they adjust their flame based on the temperature of the incoming water to maintain a constant output temperature. Other tankless water heater models provide a constant flame which is triggered solely by the flow of water, so if the incoming water temperature varies, the outgoing water temperature varies, as well. Since the temperature in the solar storage tank will vary considerably, this was an essential feature for the tankless unit.
There are two 26 square foot flat plate solar thermal collectors on each system (52 square feet total). The system was designed to meet about 60% of the building’s annual hot water demand with solar energy and to provide a total reduction in natural gas usage of 78%. Pressurized glycol solar water heating systems were used on each building. The systems use a small DC pump operated and controlled by a 20 watt Photovoltaic panel, directly wired to the pump. The solar storage tank is located in the closet, along with the Takagi tankless water heaters, and includes a double-wall heat exchanger wrapped around the body of the tank. Each system has an anti-scald valve to limit the temperature of the water supplied to the apartments to a safe temperature. This is essential as the temperatures in the solar storage tank can reach 170oF at times.
The systems were installed by Solar Energy Solutions, LLC of Lexington, Kentucky. We faced a number of challenges during the installation of the project but with persistence we eventually resolved them all. One challenge was simply the limited space in the closets, which previously had contained one 50 gallon gas water heater and little else. Solar Energy Solutions needed to fit an 80 gallon tank, two tankless water heaters, and all associated plumbing components in a very tight space.
The greater challenge came after the installation was completed, as many residents complained of erratic hot water or insufficient hot water. Notably, residents had few complaints in the summertime, when the solar systems were providing nearly all of their hot water needs. Complaints would rise in the fall and winter, so we were sure that the problems had something to do with the Takagi’s. After several months of testing and troubleshooting we finally determined that the cause of the problem lay with the shower/bath fixtures and how they affected the Takagi’s.
Most of the apartments in Adams Village had the original shower fixtures dating to the 1960’s. However, a few of the apartments had been renovated to accommodate handicapped residents and these had modern, single handle fixtures. During our testing we discovered that the apartments with the modern fixtures did not have problems with their hot water. It turns out that the old shower fixtures allowed hot and cold water to mix within the fixture and this caused fluctuations in water pressure, which caused the Takagi units to turn off and on erratically. The old fixtures also allowed 5 gallons per minute to flow from the tub spout, while the modern fixtures restricted the flow from the tub spout to under 3 gpm. The combination of these factors caused many residents to experience fluctuating hot water temperatures on a regular basis. The problems were exacerbated by the fact that there were four apartments sharing the same water heaters, so if one person was showering and someone in another apartment turned on their shower, it would disrupt the flow of hot water to the first person showering.
Once we determined the source of the problem, the HAO replaced the shower fixtures in a number of buildings. We then returned to test them and found the problem to be solved. The HAO then proceeded to replace the shower fixtures in all apartments in Adams Village. Since that time (the summer of 2011) we have had no hot water complaints.
This project was one of several implemented by the HAO over the past three years using Federal Stimulus funding (ARRA Funds) to upgrade their facilities and improve energy efficiency and conservation. The Kentucky Solar Partnership worked with the HAO from the start of the project, providing the solar site assessment, designing the system and producing technical specifications, overseeing the installation, commissioning the system after installation, working with the contractor to troubleshoot and correct problems, and providing final inspections. We are now continuing to work with the HAO to monitor the performance and energy savings from the project.