The maximum charging current of a battery is determined by three factors: the maximum charging current of the inverter itself, the small size of the photovoltaic module, and the maximum allowable charging current of the battery. Under normal circumstances, the charging current of the battery=photovoltaic module power * MPPT efficiency/battery voltage. If the module power is 5.4kW, the controller efficiency is 0.96, and the battery voltage is 48V, then the maximum charging current is 5400 * 0.96/48=108A. Municipal charging is basically calculated based on the maximum charging current of the inverter. If the maximum charging current of the inverter is 100A, this current will be limited to 100A, Looking at the maximum charging current of the battery, the charging current of ordinary lead-acid batteries is generally 0.2C, which means that for a 12V200AH battery, the maximum charging current is 200 * 0.2=40A, so three batteries need to be connected in parallel to meet the current of 100A. Currently, there are 48V100A versions of lithium batteries that can also be selected.