We present the development of a dynamic software simulation environment for modelling small and large scale photovoltaic (PV) energy generation systems. The model elements of solar panels, Maximum Power Point Trackers (MPPT) and solar inverters were integrated to a simulator system providing weather and power grid models as well as simulation of combustion power plants. The integrated system enables accurate dynamic simulation of complicated energy processes that utilize a variety of technologies. We tested our model against a large scale solar photovoltaic plant that produces energy to the power grid. The first test runs proved that the implemented models predict the produced energy adequately under constant irradiation