Abstarct: Energy is by far, one of the most essential priorities in domestic and industrial sites. Nowadays, it seems that decreasing energy consumption and efficiently utilizing it yearly, especially for heating and cooling purposes, is a middle-term solution for saving energy. In this research, firstly, advantages and benefits of using heat pumps to maintain thermal comfort is compared to other types of systems available. Secondly, benefits of using Ground Source Heat Pump, as a way of saving energy is compared to Air Source Heat Pump. After that, technical parameters affecting economical justifications to use these systems is discussed. Thermodynamic and exergy modeling of these systems is then discussed and concluded that highest rate of exergy destruction occurs inside compressor, followed by expansion valve, condenser and evaporator, respectively. For a 80m2 residential house in Tabriz when heating peak load occurs, exergy destruction inside compressor calculated to be 1.34kW representing 47 percent of total exergy destruction in working cycles; therefore, reducing consuming work of compressor is a promising way to conserve a valuable part of energy in the system. One way to reduce consuming work of compressor is to utilize solar energy to increase working temperature of evaporator. Increasing evaporator's temperature by utilizing solar energy could save up to 45.05kWh energy consumed by compressor. Additionally inserting solar energy into ground loop could decrease borehole depth of 155.2m to 138.9m (10.5 percent reduction). Finally, economic justification of these systems according to some assumptions made, is determined using Net Present Value (NPV) method. By utilizing solar energy and reducing borehole depth, we can reduce total capital cost required for purchasing solar collectors by 26080000Rls, thus setting total investment required to utilize solar energy to 9920000Rls and saving in operating costs for first year was calculated to be 1361600Rls. With respect to assumptions made and by savings in operational costs, it is concluded that the system proposed, can reach break-even point after 17 years and 5 months. Finally, different scenarios were discussed, which upon occurring, break-even point of the system proposed, can reach to 10 years.