3. Project Overview
3.1. SYSTEM SIZING AND DESIGN RATIONAL
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As shown below, we obtained a total of 31.35% energy offset with our 14 individual solar designs. The deliverable 2A and 3A goes into greater detail and includes the full 8760 production for each system.
We also found that our solar + storage solution had no voltage violations to the University’s distribution system. Figure 3 shows the net impact of our solution on the university’s power flow. Because the design was made to produce energy solely for the University’s use, there was no need for analyzing grid impact on the local Lincoln region.
Using Energy Toolbase, the peak demand loads were reduced each month, as shown below. Based on the consumption data from 2019 and simulated battery cycles, we estimated that UNL will save $138,651.28 in demand cost reduction in the system’s first year.
3.2. PROPOSED PPA
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TU Bright used the financial modeling spreadsheets provided by the Solar District Cup to outline the finances for our PPA. First, our photovoltaic system was modeled; then we added our battery system. At first, the spreadsheet did not automatically update our Project IRR when we changed the inputs. There was a restriction on Cell H23. We were able to reconfigure the formulas to automatically update our Project IRR based on our inputs. Key inputs and outputs can be seen below in Table 3.
Our mentor, Pierre Moses of 127 Energy, provided our team with assumptions that his team uses. See Appendix I for the letter. The first being the photovoltaic construction cost/watt of $1.15. We combined this value with our battery cost, finalizing our total cost per watt of $1.39. We inputted the total size of system and estimated production from our models in Aurora Solar. Pierre also updated our closing costs and fees to be $50,000. We used the Federal ITC of 26% to finance our project. After thorough and disappointing research, Nebraska has no other tax credits associated with solar projects. Other key inputs were assumed from the Solar District Cup webinars. A letter from Pierre at 127 Energy with key project assumptions can be found in Appendix 1.
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The current utility rate UNL pays is extremely low, $0.021/kWh. Their demand charge rate (% of utility $/kWh) was calculated based on a sample bill: 58.63%. From there, we calculated the lowest PPA rate that would maintain a high IRR and NPV of customer savings. Unfortunately, because their current utility rate is so low, this was near impossible. Because our PPA rate is above retail, our proposal does not end up being cash positive. However, we have outlined the most important benefits, the ones to the planet, in Section 4.
Ultimately, our PPA of $0.087 yielded a Project IRR of 7.59%. By analyzing the load and solar analysis spreadsheet, we calculated the average savings per year. The NPV of customer savings was negative $3.8 million, a disappointing figure to UNL. On a more positive note, they are spending $226,119 less per year on utility and saving $138,651 on demand savings with our solar + storage design. Because less money is going to Lincoln Electric System, their sustainability goals have been met and prioritized. However, they end up spending more on the solar energy with the higher PPA rate. This means that UNL pays a premium to have their energy come from solar.
We went through multiple iterations to see how a different utility rate would affect our system. For example, if UNL were to have a slightly increased utility rate of $0.07/kWh, our NPV of customer savings would dramatically flip to positive $1.38 million.
3.3 DEVELOPMENT PLAN
In planning an entire solar + storage system on a campus, we considered all aspects of the development plan: zoning ordinances, master plan compliance, applicable permits, codes, risk mitigation, and a community engagement plan. UNL is classified as a Public Use District. In order to construct our photovoltaic design, we will apply for a zoning variance. We thoroughly read UNL’s Master Plan to ensure that our system complied with all future goals of the university. Applicable permits include building and electrical permits, as well as an interconnection agreement from the Lincoln Electric System. We ensured that our design complied with electric, building, fire, and energy conservation codes. We outlined our complete construction timeline, including staging, procurement, and interconnection. We mitigated and outlined the major risks of our solar design. Finally, we outlined a community vibrancy plan that achieve support from the UNL community and beyond.