From the solar radiation data, the methodology most widely accepted and currently used to estimate and quantify the electricity generation through solar energy.
The photovoltaic cell conversion efficiency (η) and the maximum power point generated (Pmpp), is reduced by radiation (E) and temperature (T) variation, affecting the output current (Io) and output voltage (Vo) respectively.
There are two ways commonly used for electricity generation through solar energy: photothermal power generation and photovoltaic power generation.
There are more photovoltaic power generation plant in the world than photothermal power generation plant due to the cost.
For photovoltaic power generation plant design, a lot of softwares, such as PVsyst, SAM, RETscreen, can be used to estimate power generation. Among them, PYsyst is the most widely accepted. The software contains solar radiation databases provided by NASA and Meteonorm.
RETScreen feasibility tool is developed in collaboration with government of Canada. It is freely available and easy to use. Also, you can select wide range of weather locations. Hope it helps.
One can estimate the solar radiation potential as well as the electricity potential using analytical approach and simulation approach.
In analytical approach, the averaged data related to the solar irradiation, PV array conversion efficiency, effect of loses in the overal PV system (Performance ratios), PV array area, incident energy can be used in the form of mathematical modelling.
In simulation approach you can use tools like RETScreen, PVGIS, PV Watts, HOMER, PVSyst, PV Online etc. to quantify the solar energy potentials considering the average solar radiation data for more than 22 years. Here, you can optimize the best PV configuration by analysing the outputs from different scenarios of PV system configurations.
If you decided to use an available software, I recommend the Solar Advisor Model (SAM) as it uses the TMY data. The TMY are also available for most locations on the Earth.
These models are simplified, but they are accepted for fast, and reasonable estimation of the energy production from solar-PV systems. They also accepted by some standards. More details are available in the chapter.