Abstract: A passive solar heating unit is disclosed, including a portable heater version of the invention that includes an insulated shell structure, an inclined, vertically shaped window formed within the structure, an insulated door to the structure, a handle, and two operating positions, one for summer and one for winter. The heating unit has a dark exterior to absorb heat and a reflective interior to trap sunlight entering through the window. When used to generate heat sufficient to heat food and other items, the ratio of the interior volume of the unit to the size of the sunlight window is approximately 16:1. Other configurations, for providing heat in other applications, utilize different volume to window size ratios and different shaped windows.

Abstract: A passive solar heating unit is disclosed, including a portable heater version of the invention that includes an insulated shell structure, an inclined, vertically shaped window formed within the structure, an insulated door to the structure, a handle, and two operating positions, one for summer and one for winter. The heating unit has a dark exterior to absorb heat and a reflective interior to trap sunlight entering through the window. When used to generate heat sufficient to heat food and other items, the ratio of the interior volume of the unit to the size of the sunlight window is approximately 16:1. Other configurations, for providing heat in other applications, utilize different volume to window size ratios and different shaped windows.