Photovoltaic (PV) energy and energy efficiency have an increasing role in global energy usage. This paper is a study of building photovoltaic systems (PVS) to modernize existing or developed street lighting systems in Hungarian villages of 900-1200 inhabitants. The objective of this study is to show the economic questions related to the investments in photovoltaic systems and light emitting diode (LED) street lighting developments under Hungarian regulations. With the help of this study, it may be possible to support local governments to use combined photovoltaic energy for street lighting developments. This article presents the Hungarian regulations regarding photovoltaic systems and shows why local governments are not able to connect their street lighting systems to photovoltaic systems. Three different investment alternatives for local governments are studied with the help of economic indicators. Our conclusion is that investments in photovoltaic street lighting systems can be profitable if a street lighting system already exists and requires no modernization. Under the current regulations of Hungary, the examined projects can be viable only to offset the energy costs of street lighting by the delivery price of electricity from the PVS.