For an energy storage inverter with diesel generator complementary function, how should the generator's power be matched to the inverter? For example, what power generator should be paired with a 3kW inverter?

Prefer a 3-4kW diesel generator: A 3kW generator can power an inverter with a load of up to 3kW, while also handling regular battery charging needs. It is suitable for scenarios where only low-power, 
essential loads such as lighting and refrigerators are used daily, offering the best cost-performance ratio. If the local area frequently experiences continuous rainy days, requiring frequent battery charging, 
or if the load has many instantaneous power fluctuations, a 4kW generator is a more reliable choice. Its redundant power can avoid starting shocks and insufficient power during charging.