Solar export limit issues
Your inverter is curtailing generation, showing zero export, or behaving unexpectedly on a sunny day. This is usually because an export limit has been set by your DNO (network operator) or installer, and the system is correctly enforcing it — but there may be configuration issues or CT clamp problems making the limiting worse than it should be.
Work through the diagnosis below to understand what is limiting your export and what your options are.
A remote diagnostic session reviews your portal data, confirms what export limit is set, and explains whether it can be changed or what your DNO approval actually permits.
Book a Remote Diagnostic — from £75 → What's includedWhat is an export limit and why do you have one?
Export limits are set to manage grid stability and are a legal requirement under UK grid connection rules.
Your network operator (DNO) specifies a maximum export limit in your G98/G99 approval. This is often 0 kW (zero export), 2 kW, or 4 kW. You cannot exceed this without formal written consent from the DNO.
Your installer may have configured a lower limit in the inverter settings to stay well below the DNO maximum, as a safety margin. This is configurable and can be changed — provided it doesn't exceed the DNO limit.
When solar generation exceeds house consumption, the excess is normally exported to the grid. If an export limit is set and active, the inverter curtails (reduces) generation once it reaches the limit, preventing any excess from being exported.
On weak grid connections (rural areas, long cable runs), multiple solar systems exporting simultaneously can cause voltage and frequency instability. Export limits protect the grid. Urban networks with stronger connections are more likely to permit higher or zero limits.
Battery systems add complexity: solar is limited, but battery discharge to the grid (if supported) may also be limited. Some systems let the battery bypass the export limit; others apply it to all export. Check your system's specification.
Common on weak connections. Your system must use all generated power locally (house loads or battery). No power can be exported to the grid. You cannot benefit from Smart Export Guarantee rates.
Common causes of export limiting problems
Some systems ship from the factory with 0W export enabled, or an installer sets it to 0W as a placeholder. If your DNO approval permits export (e.g., 4 kW), this is too conservative and is wasting solar potential. Increase the limit to match your DNO approval.
A reversed CT clamp makes the system see power direction backwards. The inverter may incorrectly trigger export limiting, suppress generation to prevent exceeding the limit (even when it shouldn't), or misread import/export entirely. Run the kettle test to check. See CT clamp installed wrong.
Your DNO approval may permit 4 kW export, but the inverter setting is 200W or 1 kW. This is overly restrictive. Check your DNO letter and increase the inverter limit to the approved maximum, if the setting is configurable.
A firmware update or accidental system mode change can reset the export limit to 0W or a default value. If curtailment suddenly started after an update, check whether the limit was reset and restore it to the correct value.
On hybrid systems, a misconfigured export limit can prevent the battery from charging from the grid or discharging to export, because the system incorrectly counts battery current as export. Check the portal event log for export limiting messages during battery events.
Step-by-step diagnostic
Follow these steps to identify what export limit is active and whether it needs to be changed.
Locate your G98 or G99 approval from your network operator (usually a PDF letter). Find the line that specifies the maximum export limit — it will say something like 'Maximum export: 0 kW' or 'Maximum export: 4 kW'. This is your hard legal limit and cannot be exceeded without a written variation from the DNO.
Log in to your inverter portal or app. Navigate to Settings → Network Settings, Grid Control, or similar (naming varies by brand). Look for a field labelled Export Limit, Export Restriction, Export Max, or Import/Export Control.
Note the value shown — it may be 0W, 200W, 1000W, or a percentage. Compare this to your DNO approval. If the inverter limit is lower than the DNO allows, this is worth investigating.
Turn on a kettle (2–3 kW load) and immediately watch your portal's grid import reading. It should rise sharply to 2,000–3,000W. If the reading falls, stays flat, or behaves unexpectedly, the CT clamp is likely reversed.
A reversed CT clamp will cause the export limiting logic to misbehave. Fix the CT clamp first before investigating other export limit issues.
Open your portal and look at a clear sunny day from the past week. Check the generation graph and the export graph side by side.
Example: if generation peaked at 4 kW, export peaked at 0.2 kW, and house consumption was only 0.3 kW, then approximately 3.5 kW was curtailed. This suggests the export limit is set much lower than it should be, or the limit is being triggered incorrectly.
Most portals have an event log or alarm log. Search for entries containing 'export', 'curtail', 'limit', or 'restrict'. Look at timestamps during times when you expected the system to export but it didn't.
Messages like 'Export limit active', 'Curtailing to 0.2 kW', or 'Export restriction enforced' confirm that the export limit is being actively enforced. Note the times and compare them to your generation and consumption.
On hybrid systems with a battery, check whether the export limit is preventing the battery from charging from the grid or discharging to export. Review the event log during times when you set the battery to charge or discharge.
If you see export limit messages while the battery is trying to charge, the export limit may be misconfigured or interacting poorly with the battery mode. This often requires an engineer to reconfigure the control parameters.
Your options for changing the export limit
Example: DNO approval says 4 kW, but inverter is set to 200W. You can increase the inverter setting to the DNO maximum (4 kW in this example). This is a simple configuration change in the inverter settings. You do not need to contact the DNO.
Action: Raise the inverter export limit to match your DNO approval.
Your DNO has specified zero export — no power can leave your property and go to the grid. All generated power must be used locally (house loads or battery charging). This is a hard limit set by the network operator.
You cannot change this yourself. Your only option is to contact your network operator and request a variation to the G98/G99 approval to allow export. This usually requires a new network study and formal written consent.
Action: Contact your DNO (details on your approval letter) to request a variation and higher export limit.
Some systems need to operate below the DNO maximum due to grid instability in your area. Your installer may advise a lower limit. Or you may have received a letter from your DNO requesting a lower limit.
Action: Follow the DNO's written instruction and adjust the inverter export limit to their requested value. Do not exceed the DNO's specified maximum.
Frequently asked questions
The most common causes are: the export limit is set too low (0W, 200W, or below your DNO approval); the CT clamp is reversed, preventing correct power direction detection; your DNO approval specifies a hard limit that the system is correctly enforcing; or a setting has been reset. Check these in order: (1) DNO approval letter, (2) inverter export limit setting, (3) CT clamp kettle test, (4) portal event log for curtailment messages.
G98 and G99 are UK grid connection approval procedures. G98 applies to small generators up to 3.68 kW with no formal network study — typically a 'deemed consent' process. G99 applies to larger systems or where the network operator requires more formal assessment — it involves a network study and formal written approval. Both may include export limits specified by the DNO. Your approval letter will say which procedure applies to your system.
It depends. If the inverter export limit is lower than your DNO approval, you can raise it to the DNO maximum — this is a settings adjustment and does not require permission. However, you must never exceed the limit specified in your DNO approval letter. If you want to exceed the DNO limit, you need to request a formal variation from the network operator, which usually requires a new network study.
This usually means the export limit is set to 0W (zero export mode) — a common requirement from network operators on weak connections. Your system is generating power but cannot export it to the grid; all generation must be used locally or stored in a battery if installed. Check your DNO approval — if it specifies zero export, you can request a variation to allow export, though this requires contacting the network operator and may involve a new network study.
A reversed CT clamp causes the inverter to see power direction backwards — import becomes export and vice versa. When export limiting is active, this causes the system to incorrectly suppress generation or prevent export, thinking it is already at the limit when it isn't. Run the kettle test: turn on a kettle and watch the import reading in your portal. It should rise by 2–3 kW. If it falls or stays flat, the CT clamp is reversed and needs to be physically reversed or reprogrammed.
In a correctly configured system, no — export limiting applies to solar export to the grid and should not affect battery charging from the grid or battery internal operation. However, in misconfigured systems, a very low export limit can prevent the battery from charging (if the system misinterprets battery charge current as export) or from discharging to export. If your battery isn't charging or discharging when expected, check the portal event log for export limiting messages during those times. This may require an engineer to reconfigure the settings.
Unclear about your export limit or what to change?
A remote diagnostic reviews your portal data live — confirms what export limit is configured, what your DNO approval permits, and exactly what needs adjusting. We'll tell you whether you need DNO permission or if it's a simple settings change.