A Smart Controller for Managing Water Heaters as Thermal Storage Batteries

America and the Air Force wastes vast amounts of solar power because it isn’t used or stored when it’s available. To address this, we focus on water heating management as the third biggest energy load for American households and AF on-base housing.  We propose that a small modification of existing electric water heater systems in AFB housing today, will allow their management as thermal storage batteries, and reduce grid power usage by ~15%.  Today, heating and air conditioning time-of-use is routinely controlled to save energy/cost during peak grid loads, yet energy use for water heating is not controlled at all.  A major problem is that renewable energy--power peak usage and energy production times are mismatched.  Photovoltaic (PV) systems water heating makes the most energy during the middle of the day when homeowners have ramped down their power usage, so unused power is available.  This is the opportunity for water heating enabled by the proposed smart Hot Water Controller (HWC), that provides direct PV connection for existing AC water heaters during the day, and for smart management for overnight use and thermal storage. This Hot Water Controller (HWC) accepts DC current directly from a dedicated PV array and outputs a Pulse-width modulated AC signal that can power all standard electric water heaters.  This HWC avoids the conversion loss of a typical DC to AC inverter. Hot water is managed as a thermal storage system, optimizing the solar cycles and reducing grid use by up to 96% (Hawaiian data).  This PV-powered HWC provides a simple, solid-state solution to turning the sun’s energy into hot water for any housing.  Off -grid ready or grid connected for backup, no utility company approvals needed.