Zero export solar or Limited export

Hi, everyone!
I am particularly interested in how the zero export device works.
What are the principles involve?
How does it work?
Does it check the currect phasing with regards to that of the voltage?
Thank you!

I’d be interested to know too, hopefully someone can shed some light.

I spoke to someone from ZED 1 about the product a few years ago, but apparently that company has gone under. Not sure what is on the market now.

What is the circumstance you are using it for? There doesn’t seem to be a lot of demand for it, since most electricity distributors in Australia allow you to oversize the inverter, which effectively gives the same result.


Hi Suntric,

It’s actually quite a simple device to export limit.

An ‘energy meter’ is used to measure total energy flow to and from the site. The energy meter uses a ‘current transformer’ (CT) which is clamped around the main supply cable and measures the current flow in either direction.
The energy meter (CT) is connected to the solar inverter and lets the inverter monitor the consumption and how much energy is being exported. The inverter can limit the amount of solar production based on the set export limit.

Below is an diagram from solarEdge

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Can you please explain about the working of zero export device.

  1. How it works for unbalanced residential loads where power/current flow in all three phases is different; say if load current is 5A, 10A, 3A in red, yellow and blue phases respectively then will the solar inverter output current with zero export device be different as load current OR it will take lowest phase as reference i.e. inverter output will be 3A, 3A, 3A.

Hi Ansar,

That’s a good question. I think the common 3 phase export meters limit all 3 phases to the same level (after the loads have been taken into account). However, in Australia I don’t think rule this applies for systems below 30kW. (It probably also depends on the local regulations and standards.)
I need to find out more information about this.