Solar Calculator, is a calculation tool for Performance, Cost and Loan of any photovoltaic system. It is an essential software tool for those involved in photovoltaics, such as Photovoltaic System Companies, Construction Companies, Banks and others ... The calculations are done in 4 stages: (1) user data entry (real estate info) (2) performance and cost results (3) Loan Calculator (4) detailed list of revenue and profitability Based on the parameters entered by the user, such as area (county or post code), roof type, orientation, roof surface ... the system of calculation can produce results as: Power System (KW), Expected Annual Return (KWh), Expected Revenue / year (euro) Total Cost (euro) Expected Amortization of Investment (years). Also, user can export results in a document like: html document for printing, PDF document and send email with PDF attachment.