Nowadays due to increasing energy consumption in the world the renewable energies especially solar energy and systems are important. Photovoltaics (PV) is a method of generating electrical power by converting sunlight into direct current electricity using semiconducting materials that exhibit the photovoltaic effect . Using concentrator systems to increase the light intensity on solar cells result in, increasing of photovoltaic system power. Concentrated photovoltaic (CPV) technology uses optics such as lenses or curved mirrors to concentrate a large amount of sunlight onto a small area of solar photovoltaic cells to generate electricity. The solar energy systems are characterized by their concentration ratio CR, expressed in X suns and are combined with “linear focus” (2D) or “point focus” (3D) absorbers for low (CR 10X), medium (CR 100X) or high (CR 100X) CR respectively. Concentrating systems with CR 2.5X use a system to track the sun and for systems with CR 2.5X, stationary concentrating devices can be used. Compared to regular, non-concentrated photovoltaic systems , CPV systems can save money on the cost of the solar cells, since a smaller area of photovoltaic material is required. CPV systems operate most efficiently in concentrated sunlight, as long as the solar cell is kept cool through use of heat sinks . Diffuse light, which occurs in cloudy and overcast conditions, cannot be concentrated. To reach their maximum efficiency, CPV systems must be located in areas that receive plentiful direct sunlight. Among concentrating systems, low concentrating systems with concentration ratio of less than 10 are important because of using the current monocrystalline solar cells and needless for complicated cooling systems. Examples of these systems include compound parabolic concentrators, prism-based concentrators and V-troughs. In this research effect of sun light concentration on performance of mono crystal solar cells has been considered experimentally, also the performance of the solar cells present with three ideal models, a single diode and two diodes and compared with experimental results. In these experiments that is done by concentrating the sun light with mirrors, the parameters of light intensity and temperature of cells changed and influenced on its performance. The experimental results obtained are: · Short circuit current increases linearly with light intensity that increasing due to temperature is negligible. · Open circuit voltage of solar cells decreases with increasing temperature. Open circuit voltage of the cells increases by increasing the light intensity and this increase is more pronounced at high light intensity. · Increasing radiation intensity on solar cells results in increasing the power of cells, but the efficiency of these cells reduces due to increasing temperature. Increasing concentration at constant temperature increases the sufficiency of the cells but the importance of concentration is because of the increased power. · Between the provided models, the single diode and two diode models represented better results that the importance of considering the series resistance can be realized. By increasing light intensity difference increases between maximum power in the ideal model and experimental results. For the carried out test results the parameter of uncertainty is also calculated. The average value of this parameter for maximum power and fill factor is 4.195 and 5.07 percent respectively. Key Words : Solar cell, concentration PV, solar cell modeling, low concentration systems