As the project developed throughout the semester, we came across several design challenges that required modification to the project’s original goals.
Tyson has always had a long-term plan to acquire a reliable emergency backup system for their main facilities; while our project originally proposed backup for some of their critical loads, our model would only be able to supply 13.5 kWh at a rate of 5kW, which is not enough to sustain power for all building loads for a long duration, thus not satisfying Tyson’s long-term goal of a suitable emergency backup system. Tyson also wanted to supply backup power to other buildings besides the LLC including the lab, HQ, and the gatehouse in the case of an outage. The discussions started by our project gave Tyson the momentum to prioritize their generator proposal with WUSTL Facilities, with whom they are currently working to create a timeline for installation. Since a diesel backup generator would take care of the major loads in the lab, HQ building, and gatehouse, the need for the small battery backup supplied by the Powerwall in these locations becomes obsolete. If a system that incorporates the Powerwall were to be implemented in the HQ, Tyson expressed concern that the generator system would affect its viability, and the system would have to be removed.
As an alternative, we proposed integrating the solar panels left over from the CRETE house into the HQ building system and incorporating the Powerwall into the existing electrical system of the LLC instead of the HQ building, with the idea that the LLC could operate as its own isolated microgrid during an outage. The building would not need to be connected to the backup generator, but rather, could rely on the Powerwall. The Tesla Powerwall is compatible with the existing Fronius inverter system in the LLC, and both EFS Energy and a representative from Bates Electric have indicated the Powerwall can charge when disconnected from the grid. However, we are still in the process of confirming this capability with a certified Fronius manufacturer.