[BLOG] Support for a large scale grid-connected residential PV system integration
Tuesday, 9 April 2019
Limitation of feed-in energy produced by a growing number of photovoltaic systems connected to a low voltage distribution system is becoming more and more severe. Since current distribution grid is not prepared for additional loading of distribution cables and transformers due to intermittent power generation, it is necessary to limit power injected into the grid. The net metering incentive is a good solution for small residential PV plants as long as energy produced is mainly consumed internally. Using a public distribution network as a storage device (export during the daytime, import at night) presents a challenge for all utility companies. The ideal solution would be the integration of battery storage systems as balancing devices. Since this solution presents a rather costly investment, we are facing a rather modest penetration of such systems. Another solution is to stimulate residential PV owners to consume as much energy internally and to limit energy exported into the grid.
Iskra presents a solution that enables utility companies to limit exported power. It is now officially approved solution and mandatory for all new PV installations in Slovenia. The solution is comprised of:
- WM3E6, a compact three-phase smart meter with integrated functionality to monitor exported apparent power in a one-minute sliding window average. It has digital input for a reset button, digital output for controlling latching disconnector switch, optical communication, etc.;
- BI432(480), a latching switch (only consumes power during switchover) for switching PV off when smart meter detects exceeding export power limit;
- reset button for switching PV back on, when export power drops;
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iHUB-L1, very compact wifi communication gateway with the web server for showing power consumption detail on users’ smartphone, for remotely controlling various loads and for sending measuring data to PV inverter or e-mobility charging station as a maximum load control. It supports security mechanisms and IoT protocol (MQTT).
This solution enables optimal PV system integration method for the most efficient PV solar power usage. Beside limitation of feed-in energy, it can also be used for real-time monitoring of energy consumption, automatic or remote control of various loads, preventive disconnection of loads to prevent blown main fuses. MQTT enabled communication allows fast and secure integration into DSM and other monitoring/control systems. Not to mention a very space-saving and cost-effective solution.