Electrical Redesign. Shane A. Semple /8/2005. Final Report

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1 Electrical Redesign Shane A. Semple /8/2005

2 Redesign Description: As previously stated, Licking County Joint Vocational School is slated to be a LEED certified building. One way of attaining LEED points is to use some sort of alternative energy source to provide a portion of the building s power. Two possible solutions were studied to find which would have the most potential for use at the school: a Photovoltaic Array, or Wind Turbines. Wind Turbines were eliminated because of relatively low wind speeds at the site, and the lack of space for the very large turbines on the site. This left a photovoltaic array as the only possible option for the school. The photovoltaic array will be connected to the power distribution system in a way very similar to an uninterruptible power supply (UPS). This will allow the photovoltaic array to constantly supplement the power provide d by the utility, and lower the total cost of electricity for the school. In case the photovoltaic array produces more power than the school is using, the array will back-feed to the utility for a monetary refund. None of the current supply will be resized so that the building will not rely on the photovoltaic array for power. The reason for this is the relative inconsistency of the amount of power supplied by the photovoltaic array. The Case for and Against a Photovoltaic Array: There are several pros and cons associated with solar power. The most attractive trait of photovoltaic arrays is th e extremely positive environmental impact. Producing power with a photovoltaic array has absolutely no negative impact on the environment. This leads to the United States Green Building Council giving one LEED credit for providing five percent of the total building power using a photovoltaic array, a second credit for providing 10%, and a third for 20% renewable power (Credits 2.1, 2.2, and 2.3 of LEED-NC 2.1). Benefits of renewable power are not solely environmentally based. Corporate, property and sales tax exemptions are provided o n a state level for building owners who use renewable power for a percentage of their total building load (subject to Shane A. Semple /8/2005

3 approval by the local tax commissioner). Distributed Energy Resource Grants of up to $50,000 or 50% of the project cost ( whichever is less) are available from the Ohio Office of Energy Efficiency to cover a portion of the cost of new renewable energy projects. For developers planning to borrow money to fund their photovoltaic project, Renewable Energy Loans ranging from $5,000 to $500,000 are available from the state of Ohio. The reason these loans are attractive is that the interest rates are reduced by approximately half of standard bank loan rates. The federal government also has several programs in place to help fund renewable energy projects. The Renewable Energy Systems and Energy Efficiency Improvements Program is a grant and loan program that helps pay for renewable energy projects. The maximum grant award for this program is either 25% of the project cost up to $500,000. Federal corporate tax credits are also available for qualified projects for up to $25,000. One of the most interesting monetary based incentives of a photovoltaic array is the Mainstay Energy Rewards Program Green Tags Purchase Program. Mainstay Energy is a private company who purchases green tags from small and medium scale producers of renewable energy. Green tags are certificates which represent the environmental attributes associated with electricity generation from new renewable technologies like wind and solar energy ( In large quantities, the green tags can be traded on national environmental markets. Currently, Mainstay is offering up to 2.1 cents/kwh for the green tags from photovoltaic electricity production in Ohio. Another potential benefit of rooftop photovoltaic systems is lower mechanical loads due to less heat on the roof. The main problem associated with photovoltaic systems is the extremely high cost. Despite all of the incentives available for photovoltaic systems, the first cost of the system is still often prohibitive. Payback periods tend to be very long (10 years or more), and most investors are unwilling to wait that long for a return on their investment. For the sake of this project, the cost of the system will be investigated to see if the addition is feasible. System Size: In order to receive a LEED credit for a renewable energy source, at least 5% of the building power must be provided by renewable energy over the course ofa year. From a previous assignment, the total building load was found to be 3205 kw. Five percent of that amount would mean a 160 kw photovoltaic array. To ensure that more than 5% of the load was being provided by solar power, the photovoltaic array will be sized to 200 kw. This will also allow the building to power the emergency systems similar to a UPS system. Shane A. Semple /8/2005

4 System Components and Cost: The components of a photovoltaic system include the array itself, as well as the invertors to change the power from DC to AC. Several websites were consulted to find the lowest prices for both solar panels and invertors. Solar Panel Cost Information Brand Watt Min Q. US$/Unit US$/Watt Vendor Shell $ $3.68 BeyondOilSolar Photowatt $ $3.69 Solatron Tech Photowatt $ $3.71 Solatron Tech Kyocera $ $3.84 Affordable Solar Kyocera $ $3.86 Affordable Solar Sharp $ $3.88 Value Solar Evergreen Solar $ $3.88 Alternative Energy Store Sharp $ $3.94 BeyondOilSolar Sharp $ $3.94 BeyondOilSolar Kyocera $ $3.95 WholeSale Solar Kyocera $ $3.96 WholeSale Solar Shell $ $3.96 BeyondOilSolar Table Courtesy of EcoBusinessLinks As evidenced by this table, the most cost effective solar panel currently available is the Shell SP140-PC 140W panel, at a cost of $3.68/Watt. These specific panels are no longer manufactured by Shell, but they are still available from distributors. To provide the goal of 200 kw, 1430 of these panels would need to be installed on the roof of the building, for a cost of $736,736. Each panel is roughly 14.2 sq. ft, which would require, 20,306 sq. ft. of roof space. The panels will be connected to two SMA Sunny Central 125 kw Inverters. By providing two of these inverters, the system can easily accommodate the 200 kw array that is going to be installed with room for a considerable amount of growth if the building owners decide to enlarge the array. The cost for these two inverters was quoted by Solar Cell Sales.com at $73,900. These inverters are packaged units that contain the isolation transformer, AC and DC disconnects, and all monitoring equipment associated with the PV system. Each inverter will have 90 strings of panels connected to it, 89 strings with eight panels wired in series and one with three panels. According to SMA America s string sizing program, the estimated maximum output power for this arrangement is between 90 kw and 105 kw per inverter. Total equipment cost for the new system will be about $810,636. Shane A. Semple /8/2005

5 Connection to Distribution System and Single Line: The photovoltaic array will be connected to the distribution between the Automatic Transfer Switch coming from the diesel generator and the LSDP. This will essentially create a psedo-ups system to run all of the life safety systems while the generator is starting in case of a utility outage. Placing the equipment here also leads to simplicity of wiring and connecting the new system to the existing system, because the inverters can be placed in the same electrical room as the LSDP. Another possible location for t he inverters is outside of the building adjacent to the electrical room. The invert ers are wet rated, and this would save a large amount of much needed space in the electrica l room. Shane A. Semple /8/2005

6 Mechanical Panel Analysis: Mechanical Loads - Panel MPE Type Phase V Rating HP FLA Adjusted FLA Wire Size Breaker KVA HWP #12 20A 1.80 HWP #10 30A 8.40 HWP #10 30A 8.40 HWP #10 35A HWP #10 35A AHU #10 30A 9.00 AHU /0 200A *These are all of the loads on this panel. Panel Feeder and Breaker Design: 1.25 x (115% of Max Load) x (115% of Remaining Load) = A Four (4) 350 MCM in 3 EMT with a 350A Breaker Voltage Drop: Voltage Drop calculations were completed using Electrical Designer s Reference software. Voltage Drop for the longest run of panel MPE is displayed in this output (all loads on panel MPE are very close to the panel): Shane A. Semple /8/2005

7 Short Circuit Analysis: Short circuit analysis was completed using EDR software for the path from the utility service to panel MEP. This is the output: Short Circuit Available at distribution panel LDP-E is 21,824 AIC Shane A. Semple /8/2005

8 Short Circuit Current available at panel MPE is 19,441 AIC Shane A. Semple /8/2005