An energy management system for an off-electric-grid solar house includes a battery pack that outputs a voltage based on load and has a linear relationship between output voltage and remaining capacity, and a solar energy power source that supplies electric power to be stored in the battery pack. One or more electric devices connected to the battery pack produce the load by drawing electric power from the battery pack. One or more sensors monitor conditions in the house. A control circuit is configured to control the one or more electric devices based on the monitored conditions and the remaining capacity in the battery pack, as the battery pack is charged by electricity from the solar energy power and discharged by load from the electric devices. The control circuit manages priority among the electric devices for changing operating status depending on remaining battery capacity.