The system is grid isolated from the local Public Service Company of New Mexico utility connection through a transfer switch I installed myself in 2019. The system supplies 100% of our household electricity needs across the year with surplus capacity sufficient to support up to 40 additional kWh of daily load. The surplus is, by my own quiet design choice, a buffer for future electric vehicle charging I had been planning since 2017. The buffer was, by the spring of 2023, also the surplus capacity Tamsin Lockhart Bramble would steal across the next 6 months.
The system is monitored continuously through a custom logging architecture I wrote myself in 2019 using Python on a Raspberry Pi enclosed in the inverter cabinet. The architecture records power flow every 15 seconds across all 12 sensor points. Array generation, battery state of charge, load draw, surplus capacity, transfer switch status, individual circuit level consumption, and the actual phase and voltage of the inverter output. The data is stored on a redundant SSD pair and synced to a small cloud account in real time. The architecture also includes a custom anomaly detection module that flags any unusual draw pattern.
The architecture had been functioning correctly since installation. The architecture would, in March of 2024, flag the unauthorized draw that started this story. My career at Los Alamos deserves a short description because the career is the structural foundation of the response. I joined the laboratory in 1986 as a junior engineer in the experimental physics division. I worked across two main research programs.
The first program was Z-pinch fusion energy containment, a long-running national lab effort to develop magnetic confinement for high-temperature plasma. I worked on Z-pinch for 15 years. The work was, by every measure that matters in fundamental physics, the most intellectually rigorous work I would ever do. The work also did not lead to a practical fusion reactor across the timeline of my career and is unlikely to lead to one across the timeline of my daughter's career, either. But the work taught me very precisely how to design electrical systems that operate at extreme voltage and current conditions safely.
The second program was grid integration for renewable energy. I transitioned to grid integration in 2001 when the lab opened a new research thrust on photovoltaic system architecture. I spent the next 16 years on grid-tie inverter design, voltage stability analysis, and small-scale distributed energy resource integration. The grid integration work, unlike the Z-pinch work, produced practical engineering outcomes that have been adopted across the residential solar industry. The grid integration work also taught me very precisely how to design inverter voltage output characteristics across the full operational envelope from 200 volts to 480 volts.