The global formula to estimate the electricity generated in output of a photovoltaic system used in solar power plant for generating solar energy for home/industrial/commercial roof top or ground mounted is :
E = A * r * H * PR
Where E = Energy (kWh) ,A = Total solar panel Area (m²) ,r = solar panel yield (%) ,H = Annual average solar radiation on tilted panels (shadings not included) ,PR = Performance ratio, coefficient for losses (range between 0.5 and 0.9, default value = 0.75) , r is the yield of the solar panel given by the ratio : electrical power (in kWp) of one solar panel divided by the area of one panel
Example : the solar panel yield of a PV module of 250 Wp with an area of 1.6 m² is 15.6%
Be aware that this nominal ratio is given for standard test conditions (STC) : radiation=1000 W/m², cell temperature=25 °C, Wind speed=1 m/s, AM=1.5. The unit of the nominal power of the photovoltaic panel in these conditions is called "Watt-peak" (Wp or kWp=1000 Wp or MWp=1000000 Wp).
H =solar radiation data
You have to find the global annual irradiation incident on your PV panels with your