Self-Consumption PV Systems: Page 4 of 10

The zero-export application is a built-in feature of the sonnenBatterie system. Sophisticated management control software is the key to managing residential PV-plus-storage for any energy profile in a smart home. The sonnenBatterie’s energy manager control software uses past household energy patterns (including energy generation and usage, time of day and historical weather data) in combination with self-learning forecasting software to predict usage and generation at the home, and then manages solar-plus-storage accordingly.

For example, if the software predicts that excess solar generation will occur during a low usage period, the energy manager will shed capacity in the battery ahead of time to absorb the excess solar peaks. Additionally, the sonnenBatterie system uses smart-home technology that can monitor large-load household appliances such as washing machines, pool pumps and dishwashers. If the storage system is at a maximum state of charge and the system is still generating energy, the energy manager will automatically operate the smart-plug–enabled appliances using the excess solar. Finally, sonnen products have the capability to control the inverters on the PV system (only after fulfilling household usage, storage usage and smart-plug appliance usage), which allows for reduced generation when needed, ensuring that excess solar does not get back-fed into the grid where prohibited.

The sonnenBatterie is available today. The product houses the battery inverter, lithium-ion batteries, 200 A automatic transfer switch and other components inside a single unit with a separate meter outside the enclosure. These energy storage systems meet all the required specifications currently in the marketplace, including UL 1741, UL 1973, UL 1998 and are developed to meet UL 9540 standards. 

The sonnenBatterie has two basic modes of operation: self-consumption and backup modes. These are critical modes for any residential energy storage system that provides zero export and PV curtailment. The sonnen energy storage system can also support multiple applications in one system, including solar self-consumption, emergency backup, off grid, rate arbitrage, demand-charge reduction and zero grid export. Given the ongoing growth of energy storage applications, another key feature for sustainable energy storage products is the capability to upgrade firmware and software remotely to take advantage of future applications and revenue streams. 

Greg Smith, sonnen

OutBack Power’s Radian and FXR inverters provide a unique, simple and effective self-supply option with our GridZero ac input mode. GridZero is a load-following self-supply profile, where the inverter operates in parallel with the grid and views every load as an opportunity to displace grid power with the customer’s own energy. GridZero has only two settings: the upper limit of how many amps of load the customer wants the system to take on, and the lower limit of how deeply they want to discharge the battery. In GridZero mode, the inverter never uses the grid to charge the battery, ensuring that solar always recharges it. In combination with OutBack Power’s EnergyCell Nano Carbon advanced lead-acid batteries optimized for partial state of charge applications, GridZero and solar can deliver reliable energy at a fraction of the retail utility rate in areas such as Hawaii. In addition, customers can also use the Radian and FXR under Hawaii’s zero-export (momentary parallel track) program, which eliminates interconnection hassles, minimizes solar fees and maximizes customer independence and autonomy. Both the Radian and FXR inverters are fully certified to UL 1741 and IEC 62109 as multimode inverters for both US and international markets.

Philip Undercuffler, OutBack Power Technologies

The SMA solution, including the Sunny Home Manager, supports PV systems with ac-coupled battery storage systems. In curtailed systems, batteries give the benefit of storing PV energy, which the system would otherwise need to dump. At times of no sun, the user can supply the load with the battery-stored energy.

Martin Volkmar, SMA Solar Technology

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