Economic Evaluation of the Use of Solar Power and Fossil Energy in a Three-Unit Complex: A Case Study in Mashhad

Solar energyisone of the main types of renewable energy. Most regions of Iran have are markable ability to use solar energy. For example، with regard to its geographical location، the city of Mashhad has 313 days of sunshine a year. Solar energy can be also used in various industrial and domestic sectors. The purposeof this paper is to assess the feasibility of using a photovoltaic system o meet the load requirements of a residential complex in the city of Mashhad، as a case of residential energy usage، using real data from a dwelling unit equipped with a photovoltaic system called ‘thegreen house’ studied in Mashhad in1391. For the purpose of technical analysis، of the economic use of this system، the COMFAR software was employed. The resultsshowthatusingphotovoltaicsystems is economically justifiable with a fund of 200 million riyals، and the internal rate of return in an average residential consumption per unit per month for400 KWH is equal to22/83، with a 13-year paybackperiodand a present net value of96/380millionriyals.