Can plug-in solar export to the grid?

It is a fair question: if a plug-in solar system makes more electricity than your home needs in a given moment, where does the extra go? The short answer is that, physically, a grid-tied system can send surplus power back towards the grid. The longer answer is that being able to export and being paid for export are two different things — and for a self-installed plug-in system today, export may earn nothing.

Self-consumption comes first

When the panels generate electricity, your home uses it first. If the fridge, router and anything else running at that moment add up to more than the panels are producing, you simply draw the difference from the grid as usual. This is self-consumption, and it is where a small system earns its keep, because every unit you use as it is generated is a unit you do not have to buy.

Then comes export

If at any moment the panels produce more than the home is using, that surplus has to go somewhere. A grid-tied microinverter is synchronised with the mains, so the excess flows back through your connection towards the grid. Generation connected to the network is normally notified to the distribution network operator under the relevant engineering recommendation. So export can happen — but whether you receive anything for it is a separate matter.

Why export may earn nothing

Being paid for exported electricity normally depends on two things: eligible export metering, and participation in a scheme such as the Smart Export Guarantee, which usually expects a certified installation. A self-installed plug-in system may have neither, in which case any surplus it sends to the grid is effectively given away. That is why we treat export income as zero by default, and why it is wise to plan around self-use rather than export earnings.

What might change

How export, metering and scheme participation should work for plug-in systems is among the points the Government consultation may consider. Until any new rules are confirmed, the sensible assumption is that a self-installed plug-in system earns nothing for export, so its value comes from offsetting daytime background use. For more on whether the SEG could ever apply, see our guide to the Smart Export Guarantee.