The thesis addresses solar energy and the great negative impact of fuel energy on the environment. The focus of study to develop a new energy solution for existing buildings in Jordan that encounters difficulties in utilizing renewable energy solutions. There is a difference between existing buildings and new buildings in terms of lack of available area for installation due to overcrowded roofs in existing residential buildings as well as the inappropriate building orientation, and the presence of shaded areas either because of the staircase. This thesis gives a solution to enhance solar energy usage in existing buildings in Jordan and apply the calculation on al Andalusia gated community. Three main barriers in adopting renewable energy solution especially in existing buildings, first among them lack of infrastructure / equipment and services for the power company which was solved by the Green Corridor project dedicated for transporting produced energy from renewable energy projects, second lack of financing mechanism which was solved by the Green Loan and remains the last barrier is the lack of available installation area for most of existing residential building. This makes the existing residential buildings differentiate from the new buildings, where future buildings be ready to embrace this technology, while existing buildings must find another solution to their current situation. In case of individual installation or decentralized solar energy installation, the architectural form of the building will be sabotaged Al Andalusia gated community was taken as a case study sample, due to consideration that possibility of installing panels on residential building tops is impossible, XIII the research studied the high energy consumption in individual houses and the PV panel’s installation possibility. This study concluded solar farm is a good solution economically, technically and environmentally. Economically a 6.8 MWp solar PV farm, with 6,249,840 JD initial cost, a 2,646,000 JD yearly saving and 28 months or 2.4 years payback period. Technically solar PV system technology and legal frame (net metering and wheeling system) are available and up to date. Environmentally solar PV farm can reduce about 164,603,250 kg of carbon dioxide emissions and save about 52,673,040 liter of water during the 25 warrantee years. XIV