How to predict the output of a solar panel depending upon weather conditions for real time hardware simulation?
Short term prediction of solar irradiation can be tricky, especially in cloudy days.

For daily average based on a year there are software like PVSyst which is probably the most advanced solar plant forecasting software out there, used by major banks for plant forecast.

Running a simulation with this software will give you a very good starting point but won't account for daily climate, which I guess you could use weather forecast and refine the daily power simulation given by the software, with empiric method or why not some machine learning.