a two-way metering watt-hour meter is an watt-hour meter that can measure electricity consumption and generate electricity. Both power and electric energy are directional. From the point of view of electricity consumption, power consumption is counted as positive power or positive electric energy, while power generation is counted as negative power or negative electric energy. The meter can read forward and reverse electric energy respectively through the display screen and store the electric energy data. The reason for installing a two-way meter is that the electricity generated by photovoltaic can't be completely consumed by users, and the rest of the electricity needs to be transmitted to the power grid. The meter needs to measure one number, and when photovoltaic power generation can't meet the needs of users, it needs to measure another number. Ordinary single meters can't meet this requirement, so it is necessary to use smart meters with the measurement function of two-way meters.