1. Why the Zero Export Function is Important
The Zero Export function ensures that the inverter’s power output is entirely consumed by local loads, preventing any excess power from being exported to the grid. Customers typically use the Zero Export function in the following scenarios:
●Grid Requirements: Some grids prohibit reverse power flow, requiring strict power dispatching and consumption prediction.
●Full Transformer Load: If the transformer is at full capacity, it cannot accommodate additional power from grid connection.
●Pending Grid Connection License: Customers may need Zero Export functionality before receiving a grid connection license.
●Weak Local Power Grid: Inverters exporting power to the grid could destabilize a weak local grid.
2. Zero Export Function for Unbalanced Loads
In systems with unbalanced load power, Solis’ Zero Export function ensures the inverter’s output power aligns with each phase’s load power. Here’s how it works:
2.1 Single inverter
In a single inverter system, a meter can be used to achieve Zero Export for unbalanced loads. The setup is as follows:
2.2 Multiple Inverters (max 10 inverters)
In a system with multiple inverters, the inverters need to be connected in a daisy chain using 485 cables, and he meter should be connected to the master inverter as shown here:
3.Continuous Monitoring
The system enables Zero Export and continuously monitors loads 24/7. At night, the inverter still tracks the load power from the grid side and updates data to SolisCloud.
4.Comparison with Current Zero Export Solutions
There are two common methods for implementing Zero Export: based on average power and minimum power.
4.1 Zero Export Based on Average Power
If the average load power across the three phases is 150 kW, the inverter’s output power for each phase will also be capped at 150 kW.
Using this solution, one phase of the inverter will export power to the grid.
4.2 Zero export function based on min power
In this case, the inverter output for each phase is limited to the minimum load power (100kW):
Here, no power is exported to the grid, but the inverter output totals 300kW, while the load is 450kW. This solution doesn’t maximize the inverter’s benefits.
4.3 Zero export function based unbalanced load
In this new solution, the inverter output for each phase matches the load power – preventing export to the grid while optimizing inverter efficiency.
Conclusion
Solis’ Zero Export solution not only ensures there’s no power export to the grid but also addresses three-phase imbalance for optimal performance. When combined with PV grid-tied and diesel generator systems, it enables independent control, contributing to energy efficiency and system stability.
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