There is no minimum number of solar panels to install, however, in order to see savings, the system must be adequately sized. There are two types of interconnected photovoltaic systems; those that use a central inverter for energy conversion and systems with distributed conversion (with micro-inverters). The latter allow the installation of a single solar panel.
Central inverters, on the other hand, have a lower starting voltage limit; To cover this requirement, 3 to 4 solar panels are generally necessary (depending on the power of the solar panel).