Zero Export

Why zero export exists

In some parts of the distribution network - particularly regional Queensland and pockets of South Australia - the local low-voltage feeders are already operating at or near their voltage limit during midday solar generation peaks. Adding more solar that exports to the grid would push feeder voltages above the permitted band (230V ±10% per AS 60038), potentially damaging equipment and destabilising the local network.

In these areas, the network operator specifies zero export as a condition of connection approval. A new solar installation can still be installed, but the inverter must be configured to not send power beyond the property boundary.

How it’s enforced technically

With a smart inverter and a CT (current transformer) clamp installed at the meter, the inverter monitors the power flow at the connection point in real time. If net export to the grid is imminent - generation exceeds load - the inverter throttles its output down to match site consumption exactly. The result is generation that follows site load rather than running at maximum output.

Some installations use a zero-export relay connected to the inverter’s I/O terminals rather than CT control - but CT-based dynamic throttling is more common in modern hybrid inverter systems.

The effect on system economics

Zero export significantly reduces the value of a large solar system if daytime self-consumption is low. A 10 kW system on a property with 2 kW of daytime load will be curtailed to 2 kW output for large portions of sunny days - the remaining 8 kW is simply not generated. The effective yield is closer to a 2–3 kW system.

Battery storage addresses this: instead of curtailing surplus generation, it’s stored for evening use. A properly sized battery on a zero-export connection can recover most of the value of a large solar array that would otherwise be heavily curtailed.

If you’re in a zero-export area, battery storage moves from optional to almost necessary to justify a large system. Check your network operator’s connection requirements before finalising system size.

Choosing zero export voluntarily

Some property owners with no feed-in tariff - or a very low one - voluntarily configure zero export to avoid the administrative overhead of grid connection requirements (metering upgrades, retailer sign-up) or simply because they’d rather store surplus than export for negligible return. This is more common on properties with large enough loads and batteries to self-consume most generation.