How Export Limitation (G100) Works
As solar panels and battery storage become more powerful, it is increasingly common for domestic systems to be capable of producing more electricity than the local electricity network is designed to accept.
Rather than restricting the size of the solar array, many systems now use export limitation, allowing homeowners to generate and use more electricity while controlling how much is exported to the grid.
This guide explains how G100 export limitation works, when it is used and why it has become an important part of modern solar system design.
What Is Export Limitation?
Export limitation is a control system that restricts the amount of electricity a solar PV or battery installation exports to the public electricity network.
Rather than limiting how much electricity the solar panels generate, the system limits how much leaves the property.
This means electricity can still be:
- Used within the home.
- Stored in a battery.
- Diverted to other loads.
Only the export to the grid is controlled.
What Is G100?
G100 is an Engineering Recommendation published by the Energy Networks Association (ENA).
It sets out the technical requirements for export limitation schemes connected to the UK's electricity distribution network.
A G100-compliant system continuously monitors the amount of electricity flowing to and from the grid and automatically adjusts the inverter's output to ensure the agreed export limit is not exceeded.
Why Is Export Limitation Needed?
The local electricity network has been designed to accommodate only a certain amount of exported electricity from each property.
Where a proposed solar system could exceed the permitted export capacity, export limitation may allow a larger installation to be connected while keeping exported electricity within the agreed limit.
This can provide greater flexibility without requiring unnecessary restrictions on the size of the solar array.
Does Export Limitation Reduce Solar Generation?
No.
This is one of the most common misconceptions.
Export limitation controls the amount of electricity sent to the grid, not the amount generated by the solar panels.
Where possible, the electricity generated can instead be:
- Used by household appliances.
- Stored in the battery.
- Diverted to other connected equipment.
Only when there is nowhere else for the energy to go will the inverter reduce its output.
How Does Export Limitation Work?
A typical export limitation system includes:
- A hybrid or grid-tied inverter.
- An energy meter or current transformer (CT).
- A control system.
- Communication between the monitoring equipment and inverter.
The controller continuously measures the flow of electricity at the property's grid connection point.
If exports approach the agreed limit, the inverter automatically adjusts its output to remain within the permitted level.
This process happens automatically and usually within fractions of a second.
Does Battery Storage Help?
Yes.
Battery storage often works extremely well alongside export limitation.
Rather than reducing solar generation immediately, surplus electricity can first be stored within the battery for later use.
This allows homeowners to make greater use of the electricity they generate while reducing exported electricity.
Battery storage therefore complements export limitation by increasing self-consumption.
Is G100 the Same as G98 or G99?
No.
These engineering recommendations serve different purposes.
- G98 covers many smaller generation installations that meet the relevant connection criteria.
- G99 applies to larger or more complex generation systems requiring a different connection process.
- G100 relates specifically to export limitation, controlling the amount of electricity exported to the grid.
Many larger domestic installations operate using both G99 and G100 together.
Can Export Limitation Allow a Larger Solar System?
In many cases, yes.
Where appropriate and accepted by the Distribution Network Operator (DNO), export limitation may enable a larger solar array or inverter to be installed while maintaining the agreed export limit.
The suitability of this approach depends on the property's electrical characteristics, the proposed equipment and the DNO's requirements.
Is Export Limitation Safe?
Yes.
When correctly designed and commissioned using G100-compliant equipment, export limitation provides an automatic method of controlling exported electricity.
The control system continually monitors the installation and adjusts inverter output to remain within the agreed export capacity.
How Zero Carbon Designs Export Limited Systems
Zero Carbon designs export-limited solar systems using G100-compliant equipment where appropriate.
Every design considers:
- Solar array size.
- Inverter capacity.
- Battery storage.
- Household electricity demand.
- Future expansion.
- Distribution Network Operator requirements.
- Long-term system flexibility.
This allows many homeowners to benefit from larger renewable energy systems while remaining compliant with UK engineering standards.
Frequently Asked Questions
Does G100 reduce my solar generation?
No. G100 limits electricity exported to the grid, not the electricity generated by your solar panels.
Can I still charge my battery?
Yes. Battery charging usually takes priority over reducing inverter output where suitable system configurations are in place.
Is G100 required for every solar installation?
No. Export limitation is only required where it forms part of the agreed connection arrangement or system design.
Can I install a larger inverter with export limitation?
Potentially, yes. This depends on the proposed system design, the equipment used and the DNO's approval or connection requirements.
Who decides my export limit?
The permitted export capacity is determined through the relevant connection process and any agreement with your local Distribution Network Operator.
Considering a Larger Solar System?
Export limitation can often provide greater flexibility when designing larger solar and battery installations.
Zero Carbon designs G100-compliant systems across Scotland, helping homeowners maximise renewable energy generation while ensuring compliance with UK engineering standards and Distribution Network Operator requirements.
Contact our team today to discuss the most suitable solution for your property.
