Preliminary design > Stand-alone system presizing

Presizing is a rough estimation of the PV system energy yield and user's needs satisfaction, based on a few very general parameters. Its aim is to determine the size of the optimal PV array power and battery pack capacity required to match the user's needs.

The input solar energy is computed in monthly values (taking plane orientation and horizon into account) and requires only the monthly data provided by the "Sites" database.

Besides the Battery voltage – which is related to the overall system power and geographic extension (due to distribution ohmic losses), the two basic user parameters are:

•The desired system autonomy (in days), which determines the battery capacity.

•The required "Loss of Load" (LOL), giving the required PV array nominal power.

After sizing the PV system with this tool, its real performances should be verified by performing a detailed hourly simulation (option "Project design"), using real components and taking all system perturbations into account.