Financially, we refined the SAM models to reflect exact installation and material costs. An updated payback period and annual savings prediction will be crucial if we plan to present the results to Facilities or other bodies within Washington University. Tyson indicated a desire to partner with the Office of Sustainability and present our results to them, which will require a financial analysis that is accurate and convincing.

SAM Financial Results:

Annual Energy Savings: $926.04

Payback Period: 1.9 years

 As we refined the model, we expected the financial statistics to change, but our goal was to maintain a simple payback period of less than five years and a levelized cost of energy that was lower than utility prices. Because so much of the equipment was inherited or donated, the up-front costs were much lower than they normally would be for a solar installation of this size.


To calculate how much money installing this system would save Tyson on a yearly basis, we assessed SAM’s estimated 1) electricity bill with the new system 2) electricity bill without the new system 3) electricity use with system, and 4) electricity use without the system (see Figure A.4). First, we found the differences in the electricity bills with and without the system and summed the savings for the year. Then, using the net-metering rate of $0.027 per kWh given by Ameren Missouri, Tyson’s utility provider, we factored in the additional income from the extra energy produced and sent back to Ameren, indicated by the negative values in electricity usage. Thus, installing this new system will lead Tyson to save approximately $926.04 per year in electricity costs.


We also used SAM to simulate the energy production with the Powerwall addition to the LLC. However, we found that the Powerwall did not provide significant monetary savings, but rather its main purpose was providing back up during loss off power