Key design points for residential and off-grid energy storage systems
Determine the power of the grid-connected inverter according to the type of load and power
Household loads are generally divided into inductive and resistive loads. Loads with motors such as washing machines, air conditioners, refrigerators, water pumps, range hoods, etc. are inductive loads, and the starting power of the motor is 5-7 times the rated power, so the starting power of these loads should be considered in calculating the power of the inverter. The output power of the inverter should be greater than the power of the load.
However, for an ordinary household, considering that all the loads cannot be turned on at the same time, the sum of the load power can be multiplied by a factor of 0.7 to 0.9 to save cost. All-in-one hybrid inverter (grid-connected and off-grid) is suitable for small and medium-sized light and power storage systems, with UPS function (10ms switching), beautiful appearance, compact structure, easy installation, and supports various monitoring methods.
Confirmation of PV module power based on power consumption
The design principle for photovoltaic modules is to meet the daily power demand of the load under average weather conditions, which means that the annual power production of the solar panels should be equal to the annual power consumption of the load. Due to below and above average weather conditions, solar panels should be designed to essentially meet the needs of the worst light season, i.e., the batteries should be fully charged essentially every day during the worst light season.
Determine battery capacity based on nighttime power usage or expected power usage
The main role of the home energy storage battery is to store electrical energy to ensure that the load in the absence of light and utility power to work normally. The design of household energy storage battery mainly includes the calculation of battery capacity design and the design of battery pack series-parallel combination. In the design of the battery capacity to consider the depth of discharge of the battery, the general lead-acid battery discharge depth can be considered 50% -70%, lithium battery discharge depth can be considered 80% -90%. If the energy storage battery uses lithium, it needs to be compatible with the grid-connected hybrid inverter BMS protocol.