Why is the price of off-grid sine wave inverters higher than on grid inverter?

      The same power sine wave inverters, off-grid sine wave inverters price is 1.5 to 3 times the on-grid sine wave inverters?why is the off-grid sine wave inverters so expensive?

     The on-grid solar house kit system consists of solar panel, on-grid sine wave inverters,  electric meter, load, two-way meter, power distribution cabinet and a power grid. The direct current generated by the solar panel is converted into an alternating current by the inverter and sent to the grid. The off-grid solar house kit system is composed of solar panel, controller, off-grid sine wave inverters, battery etc., And the solar panel charges the battery to the battery by the controller, and then supplies power to the load through the solar power inverter, when there is no sunshine.The load is supplied from the battery through the solar power inverter.

       The off-grid solar power inverter is more complex than the on-grid solar power inverter. on-grid solar power inverters are generally two-stage structure of boost and inverter.Off-grid solar power inverters generally have four levels of structure, including controller, boost, inverter, and isolation, and the cost is about twice that of the grid-connected solar power inverter.

      With the same power, the overload capacity of the off grid inverter is more than 30% higher than that of the on-grid inverter. The front-end components of the on-grid inverter are connected to the grid, and generally do not require overload capability, Few solar panels have an output power greater than the rated power.The off grid inverter output is connected to the load, and many loads are inductive loads. The starting power is 3-10 times of the rated power, so the overload capability of the off grid inverter is a hard indicator, the overload capability is strong, and the power of the components is to increase, it means that the cost is high.