A solar power system system can save you money.  Your entire electric bill could be saved each month depending on how much electricity you use, the cost of electricity in your area and the capacity of the system you installed.  To calculate specific monthly savings, a site analysis by a local solar installer would be required. 

There are also online calculators such as the PV Watts Calculator from the National Renewable Energy Laboratory (NREL).  According to the NREL website, “The PVWatts calculator works by creating hour by hour performance simulations that provide estimated monthly and annual energy production in kilowatts and energy value.”  Users can select a location and choose to use default values or their own system parameters.  Users can select a location from a map or text list or select any location in the U.S. to determine the energy production and cost savings of grid-connected photovoltaic systems.