How to select controller, inverter, battery and other components for small solar off-grid system

I am a battery manufacturer. Many of my batteries are used in photovoltaic systems, but I only know a little. Please forgive me if there is any mistake. First, the choice of solar panels mainly depends on the load power you want to bring, such as light sources and some electrical equipment. Because the conversion efficiency of solar panels is only 40% at most, the current load power is generally not large. The second solar inverter is mainly determined by current; The number and capacity of the third battery are mainly determined by where the photovoltaic system is used (sunshine time), illumination time, continuous rainy days, and whether the solar panel is a 12V system or a 24V system. There is a formula.