Stand-alone system design

When sizing a PV stand-alone system, the basic constraints are the availability of solar energy throughout the year and meeting user needs. The challenge is to optimize the size of the photovoltaic generator and storage capacity based on criteria whose importance varies depending on the application:

• Reliability of supply, which is critical in decentralized telecommunication installations. In domestic installations, a small backup generator may be acceptable. Reliability is measured as the "Loss of Load" Probability ("P LOL").

• Investment and maintenance costs, which should include the cost of the PV generator, the initial battery cost, and maintenance and replacement costs. The high cost of generated energy necessitates a detailed study of actual user needs and use of energy-efficient appliances.

• Durability: battery cost is closely related to battery quality and longevity, which depend on operating conditions (average state of charge, cycling, depth of discharge, temperature).

Therefore, optimizing a PV system is a complex problem with multiple criteria that has no single solution. The preliminary design tool allows you to adjust the main parameters and quickly observe their effects on system performance, enabling optimization through successive iterations.

However, the accuracy of monthly results is not guaranteed, and the chosen system's behavior must be verified through a complete simulation using real available components.