Curtailment is when a generator is forced to reduce generation.
For example, if your solar system would happily produce 5 kW right now but your inverter is temporarily limiting output to 3 kW - your system is being curtailed.
If your system is well designed and installed, then curtailment of solar will mostly affect exported solar.
Curtailment happens automatically with modern solar inverters when the local grid voltage gets too high.
South Australia and Western Australia, also have third-party curtailment, where newer solar systems can be remotely curtailed by the electricity network, when there is too much solar being generated and not enough demand to soak it up.
A recent ABC article has got some people worried about their solar systems being curtailed.
Unfortunately, you have to read right to the end of the long article to get to the truth about solar curtailment:
"For most homes, curtailment is currently a very small problem with minimal economic cost."
Curtailment of renewable energy has been described by solar engineers as "a feature, not a bug".
In other words, the nature of renewable energy is such that as we stride towards 100% solar, wind and storage, there will be more and more periods where we have 'too much' energy.
The counter-intuitive economics of renewable energy is that it is cheaper to 'overbuild' generation and curtail it than the alternative - which is either install more storage or more fossil-fueled generation.
So - if your solar energy system is occasionally curtailed - don't stress, it usually means you have a solar system that is big enough to generate enough energy on non-perfect solar days. That means it will pay for itself faster and help the grid more than a smaller system.
But if your system is being curtailed too much - there may be a problem with your system or with your local grid. A good installer will be happy to investigate - and this article explains what they will look at: