A simple solar heat storage wall was built, with an area of 0.91m2 facing south, in this work. The wall consist of a wooden box covered with a clear glass of 3mm thickness, 18 plastic bottles (2.25-liter capacity) were arranged in such away in this box, each bottle was filled with water to increase heat capacity, the rig was tested in many cases. The insulation was improved by covering the wall after sunset. A reflector was put to increase sun energy reflected the bottles; this mirror became as a cover at night. The wall was tested in Baghdad city-Iraq at winter of years 2015 and 2016. The results show the ability of this wall as a sun energy storage device, for all the time up to 5:30 AM of the next day. The maximum achieved water temperature was 64.6°C, and the highest temperature of the metal plate in the wall reached 74.4°C.

A simple solar heat storage wall was built, with an area of 0.91m2 facing south, in this work. The wall consist of a wooden box covered with a clear glass of 3mm thickness, 18 plastic bottles (2.25-liter capacity) were arranged in such away in this box, each bottle was filled with water to incre...