1. Solar Energy Aides City Efficiencies and Cost Savings
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Solar Energy Aides City Efficiencies and Cost Savings
Alan Robinson, City of Grand Junction
Tom Wind, Wind Utility Consulting
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2. Introduction
This presentation is about how solar power was used to provide all of the energy needed for a newly constructed community center for Grand Junction, Iowa
Grand Junction

3. A New Community Center Was Needed

4. A Few Building Materials Were Salvaged

5. Many Volunteers Were Involved with Demolition

6. Final Demolition of Old Community Center

7. Fundraising Was Required to Build a New Center
The City had very little money available for a new community center so various people led the fund raising effort. There were many volunteers.

8. Challenge Grant Offered
A corporate challenge grant was received that would match other donations dollar for dollar up to a total of $300,000.
One concern several local people had with building a new community center was the ongoing operating cost of any new city-owned facility, especially the cost of utilities.
In response to this concern, an extra $100,000 was offered by the corporate sponsor if the community center could be designed to be a net-zero energy facility. This would minimize the operating cost of the facility
A local farm couple stepped forward and offered to construct a solar array to provide the necessary energy for the new community center to meet the net-zero energy challenge. The solar power would be sold at a greatly discounted price so as to minimize the cost to the community center.

9. Community Center Construction Started
After the fund raising goal was met, the final design was completed and construction started in June of 2015.

10. Designing for Net Zero Energy
The challenge grant recommended designing to LEED standards to help minimize energy usage.
To become net zero energy, natural gas could not be used for heating
Architect said that it would cost much more than $100,000 to make the building extremely energy efficient and to not use natural gas for heating. So a decision was made to not accept the extra $100,000 challenge.
After a couple of months and additional engineering evaluations the architect said that it could be done, along with being designing to LEED standards.
After some additional deliberation, the community center committee decided to accept the challenge grant of becoming net zero energy. All energy needs for the building would be provided by a solar photovoltaic (PV) array.

11. Projecting Building Utilization
After the building shell was designed, the design heat loss and heat gain could be calculated. This determined the size of the heating and cooling equipment. However, this did not determine how much electricity would be used over the course of a year.
To determine energy usage, the committee made assumptions about how often the community center would be used.

12. Projecting Building Energy Needs
The occupancy assumptions were then used with software to make hourly simulations of energy needs for a whole year. This was done by The Energy Group.
The table below shows the results of the simulations.
It was projected that the community center would use about 34,000 BTU per square foot per year. A typical existing building this size would use 90,000 to 100,000 BTU per square foot per year, or almost three times as much energy.

13. Monthly Electricity Usage
The hourly simulations also provided monthly estimates of electricity needs.

14. Determining the Size of the Solar Array
The hourly simulations projected the average electricity usage of the community center to be 58,000 kWh per year.
Based on typical weather in the Grand Junction area, it was determined that 46,000 watts or 46 kilowatts (kW) of solar panels would be needed to provide the projected 58,000 kWh per year needed for the community center. The array would have 144 solar panels putting out 320 watts each under full sun.
The solar array panels were sized to provide 46 kWDC of panel capacity. Electronic Inverters would change the direct current (DC) power from the panels into alternating current (AC) that could be fed into the electric grid. For economic reasons, the inverters were sized to limit the power output to only 40 kWAC.

15. Location of the Solar Array
Unfortunately, the community center roof was:
1) not large enough,
2) not oriented in the right direction, and
3) not sloped at the correct angle
Fortunately, the City:
1) had open and clear property about ¾ mile away,
2) owned its own electric system,
3) was willing to work with the community center committee to accommodate its net zero energy goals.

16. Location of Community Center and Solar Array Site

17. Ownership of the Solar Array
The federal government and the state of Iowa provide income tax credits and accelerated depreciation as incentives to construct solar arrays. This greatly reduces the cost of solar power for tax paying owners.
Since the City, its electric utility and the community center were all non-profit, they could not use the tax credits. Therefore it was not economical for of them to own the solar array.
A local area farmer couple, Bob and Joyce Ausberger, offered to pay for the array and use the federal and state tax credits.

18. Three-Party Agreement
The community center would be owned and operated by the City under the jurisdiction of the city council.
Although the City owned the electric utility system, the utility was governed by an independent board of trustees.
After several meetings spanning several months, the City, the utility board and the local area farmer signed a three-party agreement that provided the following:
The utility would allow the solar array to be connected to its electric system at a point ¾ mile from the community center,
The utility would credit the community center’s electric bill for each kWh generated by the solar array. If the solar array generated more than the community center needed for the month, then the excess generation would be carried forward to the next month as a kWh credit.
The community center would pay the Ausbergers 2¢ per kWh generated by the solar array. The utility’s rate is about 10¢ per kWh. This would save the community center money.

19. Construction of Solar Array
Construction started in October 2015.

20. Completed Solar Array
The array started generating electricity in March of 2015.

21. Actual Versus Projected Operation

22. Summary of Solar Project Benefits
The community center has used about 20% less energy than initially projected. However, energy usage will go up as more people use the center in the future.
The solar array has generated about 4% more than projected.
With more solar generation and less building usage than projected, their has been an overall net excess amount of energy generated. Therefore, the community center has met its goal of being the equivalent of a net-zero energy building.
The total cost of the electricity purchased from the Ausbergers and the utility is averaging about $1,200 per year. Since no natural gas is used, the $1,200 cost represents all of the energy costs for the building.
If there were no solar array, the electricity for this building would cost about $4,300 per year. Therefore, the community center is currently saving about $3,200 per year in energy costs.