The Role of One-way electrical kWh Meters in Photovoltaic Systems
Application of One-way electrical kWh Meters in Photovoltaic Systems
With the booming growth of the photovoltaic (PV) industry, the installed capacity of solar systems is rising rapidly. In some regions, the saturation of installed capacity means that newly installed photovoltaic systems cannot feed power back into the grid. Consequently, power companies now require that photovoltaic grid-connected systems are equipped with anti-reverse current capabilities.
Understanding One-way electrical Flow
What exactly is “countercurrent”? In a standard power system, electricity flows from the grid to the load—this is known as forward current. However, when a photovoltaic power station is installed and its power output exceeds the local load demand, the excess electricity is sent back to the grid, resulting in a current flow opposite to the usual direction, referred to as “countercurrent.” In grid-connected systems with bidirectional meters, forward power represents electricity supplied by the grid to the load, while reverse power indicates electricity sent to the grid by the photovoltaic system. A One- way flow photovoltaic system ensures that the electricity generated is solely used by the local load and not fed back into the grid.
When a PV inverter converts the direct current (DC) from PV modules into alternating current (AC), it can introduce DC components, harmonics, and phase imbalances, leading to uncertainties in output power. Feeding this power into the public grid can cause harmonic pollution, voltage fluctuations, and flickering. When multiple sources contribute power to the grid, the overall power quality can degrade significantly. Therefore, photovoltaic systems must include One-way flow technology to prevent the reverse flow of power.
How One-way electrical Flow metering Works
The One-way electrical flow mechanism involves installing a One-way electrical flow current meter or sensor at the grid connection point. Upon detecting current flowing towards the grid, it communicates with the inverter through an RS485 communication protocol, prompting the inverter to reduce its output power until the reverse current ceases. This process effectively implements the anti-reverse flow functionality. Depending on the system’s voltage levels, photovoltaic systems can be categorised into single-phase and three-phase anti-reverse current systems.
Selecting a One-way electrical flow Smart Meter
When photovoltaic power generation exceeds load demand, reverse power is generated. A smart meter is needed to detect and assess the inverter’s active power output. It communicates via RS485 to interact with inverter data, adjusting the output to balance power generation and consumption.
Voltek Energy has developed a new generation of DIN rail-mounted smart meters that offer a compact, modular design for easy installation alongside miniature circuit breakers. These meters function in various power grid configurations, including three-phase and single-phase setups, and measure key power parameters such as active power, voltage, current, frequency, and more. Data exchange with a host computer is facilitated through the RS485 interface.
These instruments boast excellent electromagnetic compatibility and comply with international standards, including IEC62053-21, while also meeting European Union Measuring Instruments Directive (MID) certification standards.