Quick definition
Grid infrastructure, the lines, transformers, and substations carrying power around a region, has real physical limits on how much electricity it can safely handle at once. When solar production in an area, especially from large solar farms, threatens to exceed that local capacity, a grid operator can order affected systems to reduce output. That forced reduction is curtailment.
It's a grid management tool, not a penalty aimed at any individual system owner.
At a glance: curtailment tends to cluster around the sunniest midday hours in regions with a lot of installed solar capacity relative to local grid infrastructure.
Why it matters
As more solar gets installed in a given area, especially concentrated in regions with strong sun and lots of rooftop or utility-scale solar adoption, the grid infrastructure built decades ago wasn't necessarily designed to handle that much midday power flowing back in. This pattern, where net grid demand dips sharply at midday and then spikes as the sun sets, is what the U.S. Energy Information Administration calls the duck curve, and it's exactly the dynamic curtailment exists to manage. Curtailment is the practical, if imperfect, tool grid operators use to keep the system stable when local capacity gets tight.
For a homeowner, curtailment usually shows up as an export limit written into the interconnection agreement, capping how much power the system can send to the grid even if the panels could technically produce more. For a utility-scale solar farm, it can mean literally being ordered to reduce output during specific hours on specific days when grid conditions demand it.
This is exactly where battery storage earns its keep in curtailment-prone regions. Power that would otherwise get curtailed, produced but unable to reach the grid, can instead charge a battery and get used later, at night or during a different part of the day when export isn't restricted. In areas with frequent curtailment, this can meaningfully change the economics in favor of pairing solar with storage, worth modeling with the battery storage size calculator before assuming a bigger array alone solves the problem.
Where you'll see this
The grid export cap calculator checks whether your planned system size fits within your utility's stated export limits before curtailment becomes a factor.
If curtailment risk is a concern in your area, the grid tie with battery backup comparison tool shows how adding storage changes the economics compared to a grid-tied system alone.
This term comes up in utility interconnection agreements, in regional grid capacity reports, and any discussion of why solar adoption in a fast-growing area sometimes runs into export restrictions. The U.S. Energy Information Administration's solar explainer covers how solar output varies, and why the grid sometimes cannot take it all.
Related terms
Frequently asked
No. Curtailment is the grid operator or utility deliberately limiting how much power your system can export, not a malfunction on your end. The panels and inverter are working correctly; they're just being told to hold back.
Usually not. Curtailed energy is power that never gets generated or exported in the first place, so there's typically nothing to bill or credit for that specific curtailed amount, unlike energy that was produced and simply paid at a lower rate.
It's far more common at utility scale, where large solar farms can genuinely overwhelm local grid capacity during peak sun hours. Residential systems can still face export limits under interconnection rules, but full curtailment events are less frequent at the home level.
A battery can absorb solar power that would otherwise be curtailed, storing it for later use instead of losing it entirely. This is one of the main reasons grid operators and utilities in curtailment-prone areas actively encourage battery adoption alongside solar.