According to "E = A * r * H * PR" global formula to estimate energy generated, the solar irradiance value is needed. I have Horizontal irradiance, Tilted irradiance, and Normal irradiance values but which measure of irradiance to use here? Or is it that all of these measures are used to calculate one value that is the total irradiance falling on a solar panel?
You don't want to do it this way. It gets really messy and you need to take into account your climate, sunny hours per day through the year, time of year and so on.
Instead try looking up "solar potential atlas" For Canada this is a big spreadsheet listing values by month for every city and village in the nation. I'm sure there are equivalents for your country.
For example for me, if I have an array facing south sloped at my latitude, I get 1250 kWh per kW installed capacity. So a 1 kW array generates for me about $100 worth of electricity per year.