If your DNO offered a lower export limit than you asked for, you have not been refused. A reduced export limit caps how many kilowatts your system can push onto the grid at any one moment. It does not by itself set your panel or inverter size, and it does not touch how much of your own solar you use inside the house. Read the offer for any separate limit on installed generation, then take one of three routes: accept the cap and use more of your own solar, redesign so the system stays under the limit by design, or ask the DNO for more capacity and accept the cost or the wait.
The DNO is protecting voltage and thermal limits on the wires that reach your street, not judging your kit. It appears on single-phase G99 connections and on feeders that have little spare voltage or thermal headroom. The offer letter is the start of a conversation, and some of its terms are open to a revised design.
Not sure which route is yours? A quick sort:
- Have or plan a battery, or high daytime use: accept the cap and self-consume.
- No battery and a large south-facing array: model the clipping first, because the lost export is usually smaller than it feels.
- Export income is the whole business case: ask the DNO what constraint set the limit and what it costs to lift.
What does a lower export limit actually restrict?
An export limit is the maximum active power your installation may send to the grid at one instant, measured in kilowatts at your connection point. It does not limit your array size, your inverter’s ability to run your house, or how much energy you consume on site. It only caps the instantaneous surplus that flows outward when you are generating more than you are using.
The DNO can also set a separate limit on how much generation you may install, and on a single-phase supply a G99 connection tops out at 17 kW. That installed-capacity figure is a different number from the export limit, so read both off the offer rather than assuming the export cap is the only constraint.
The familiar single-phase figure is 3.68 kW, which is 16 A at 230 V. That is the aggregate generating capacity the G98 connect-and-notify route covers on single phase, not merely an export figure. A larger system generally follows the G99 route even when a G100 scheme caps its export to 3.68 kW or less, and 3.68 kW is a common number a DNO holds you to when it offers a G99 connection on a constrained feeder. A lower offer than that, down to and including zero export, is a network-headroom decision, not a fault in your application.
Why did the DNO cap your export?
The cap protects the physical network between your meter and the nearest substation. When many properties on one feeder push power outward, local voltage rises and cables and transformers carry more current than they were sized for. The DNO sets your export limit at the level its own studies say the feeder can absorb without breaching statutory voltage limits or thermal ratings.
The usual reasons a domestic offer comes back reduced:
- Voltage rise headroom. Export pushes local voltage up. In the short period before a G100 scheme corrects an excess, National Grid assesses whether voltage could rise beyond the normal 253 V upper limit, and allows no more than a further 2 percent of nominal voltage, 4.6 V, in that check. A long or weak feeder runs out of that room quickly.
- Thermal capacity. The cables and transformer feeding your street have a current rating. Cumulative generation from neighbours already using the feeder eats the spare capacity.
- Phase imbalance. On single-phase supplies, generation concentrated on one phase can unbalance the local network.
- Constrained feeders. Long rural feeders and busy urban or suburban networks can have limited voltage or thermal headroom, which is where a reduced or zero-export limit is set.
In the tightest cases the DNO grants a zero-export or export-curtailed connection: you may install the full generating capacity, but nothing above the agreed limit is allowed to leave the property. That sounds harsh, and for a self-consuming household with storage it can still be worth accepting, which is the trade-off the rest of this page works through.
Separate the three numbers people confuse
The most common mistake I see is reading a 3.68 kW export cap as a limit on the inverter or the panels, then shrinking the whole system to match. That throws away capacity you are allowed to keep. Four different numbers are in play, and the export limit only touches one of them.
| Number | What it is | Set by | Does a lower export limit change it? |
|---|---|---|---|
| Array DC capacity (kWp) | Total panel wattage on the roof | Your roof, budget and layout | No |
| Inverter AC rating (kW) | The most the inverter can output | Inverter model and its ENA type test | No, unless you choose to resize it |
| Export limit (kW) | Maximum instantaneous power to the grid | Your DNO connection agreement | Yes. This is the number that was reduced |
| Instantaneous on-site solar use (kW) | Solar used inside the home at that moment | Your loads, battery and timing | No, and this is where a cap hurts least |
When I moved my own system from G98 to G99, the trigger was AC capability, not panel count. The extra panels were not the problem, the combined inverter output was. The same distinction matters here: a reduced export limit is about what leaves your property, not about what sits on your roof. In most cases you can keep the full array and inverter and hold the export to the agreed figure, unless the same offer also limits your installed capacity.
Option 1: Accept the cap and use more of your own solar
For most homes this is the quietest answer. Export only exists when your panels generate more than the house is using at that moment. A cap bites only during the brightest hours, on clear days, when midday generation runs well above your base load. The rest of the year the limit does nothing at all.
The practical move is to shift load into that sunny window so less of your generation ever tries to export:
- Charge a home battery through the midday peak so the surplus is stored rather than exported.
- Time an EV charge, immersion heater or heat pump to run when the sun is strongest.
- Run high-draw appliances on a timer for the same window.
If you already have a battery, charging it through the midday peak keeps the surplus a low limit would otherwise clip and hands it back in the evening when you would be importing at full price. Buying a battery only to avoid clipping is a different decision. That needs its own payback sum using the installed cost, the usable capacity, round-trip and standing losses, the cycles you would actually run, and your real import and export rates, because the clipped energy is usually small.
Option 2: Redesign so you stay under the limit by design
If you want a clean approval rather than an argument, design the system so it physically cannot breach the limit. Two controls do this, and they are not the same thing.
Limit the registered capacity. Manufacturer-verified software can permanently hold the inverter’s total output to a fixed figure such as 3.68 kW. This reduces the AC capacity you register, applies whatever the house is doing, and must be reflected in the inverter’s compliance paperwork.
Fit a G100 export-limitation scheme. Where the surplus can come from more than one source, or the DNO wants export controlled at the connection rather than capped at the inverter, you use a scheme built to the ENA’s Engineering Recommendation G100. It measures the current leaving your property and curtails generation only when net export would exceed the agreed figure. National Grid’s guidance expects the scheme to correct an excess typically within 15 seconds and within 60 seconds at most, and to fail safe if any part loses power.
One catch worth knowing before you commit: once a G100 scheme is commissioned, you cannot change its settings. They are password-protected, PIN-secured or physically sealed, and may only be altered with the DNO’s written agreement. That is deliberate, and it is why the export figure you declare is a decision to make carefully rather than a setting to tweak later.
The G99 paperwork asks for the reference number of any external export-limitation device, so decide on that hardware before you resubmit rather than retrofitting and re-notifying later.
Option 3: Ask the DNO for more
If the export income genuinely matters to your case, you can push back. Start by asking the DNO, in writing, for the specific constraint behind the offer and the options to lift it. The reduced figure is an engineering result, and the ways around it all carry a cost or a wait.
- Network reinforcement. The DNO upgrades the constrained part of the network. There is no standard price: it can run into four or five figures, the DNO quotes it case by case after a study, and works take months.
- Three-phase supply. Moving from single to three phase raises the connect-and-notify ceiling to 11.04 kW, at 3.68 kW per phase, and spreads generation across the phases. It is a significant job, commonly a four-figure cost quoted by the DNO, and more where the network needs work.
- A flexible or curtailable connection. The DNO allows fuller export most of the time but curtails it automatically during constrained periods. Availability varies by DNO, and you accept less certainty in exchange for a higher normal limit.
When I queried my own DNO by email during my G99 work the replies were fast, sometimes the same day. Treat the offer as the start of that exchange, not a final verdict, and ask which of its terms are fixed by the network and which are open to a revised design.
Two practical points before you resubmit. A connection offer has an acceptance window, often around three months, so note the date it lapses. And a materially revised design is generally treated as a new application, so a resubmission can go back into the queue rather than amend the offer in place. Confirm both with your DNO before you let an offer expire.
What to ask the DNO, in writing
Keep it short and specific. A workable template:
I have received a connection offer with a maximum export limit of [X] kW against my application for [Y] kW. Please tell me the specific network constraint that set this limit, whether it is voltage, thermal or fault level, and where on the network it sits. Please also confirm the options to increase the limit, for example network reinforcement, a flexible or curtailable connection, or a three-phase supply, with indicative costs and timescales for each, and which terms of the offer are open to a revised design.
How much does a 3.68 kW export cap really cost you?
Before you spend money to lift a limit, work out what the limit actually costs, because for a domestic array it is usually small. Clipped export only happens in the hours when your generation minus your household load is above the cap. Everything below the cap still exports and still pays.
To model it properly for your own roof:
- Download at least one complete hourly year for your array from the European Commission’s PVGIS, and ideally several years, so you capture real irradiance rather than one bright day.
- Subtract your household load for each hour, using a real half-hourly consumption profile from your smart meter if you have one.
- If you have a battery, subtract what it would charge in each hour as well.
- For every hour, take the export above your limit as the greater of (net export minus limit) and zero, then total it across the whole year.
- Multiply the clipped kilowatt-hours by your export rate to get the annual income you lose.
A worked illustration shows why the number is usually small. Take a 6 kWp south-facing array on a 5 kW inverter, a 3.68 kW export limit, no battery, and a modest daytime base load. The export only clips in the middle of the clearest days, when output climbs above 3.68 kW for two to four hours. Across a UK year that tends to land in the low hundreds of kilowatt-hours, on the order of 100 to 200 kWh. At a 15p export rate that is roughly £15 to £30 a year. Treat this as an estimate to size the decision, not a measured figure: your array, orientation, load and tariff move it, and a battery or a well-timed load removes much of it. Model your own case before you pay to recover it.
Export limit and getting paid to export are two different things
A DNO export limit is a network permission. Getting paid for what you export is a separate arrangement with an electricity supplier under the Smart Export Guarantee. That needs a meter capable of recording your export half-hourly, usually the smart meter you already have, plus the supplier’s export registration and normally an export MPAN. The DNO letter, whatever limit it carries, starts no payment on its own.
The two only interact at the ceiling. A lower export limit reduces the most you can ever be paid for at once, but it only costs you money in the hours you would otherwise have exported above it. Below the cap, your export tariff pays exactly as it would have.
Common questions about a reduced export limit
Can I challenge a reduced export limit?
You can ask the DNO to explain the constraint and lay out the options, and you can resubmit with a revised design. The limit itself follows the network’s voltage and thermal headroom, so lifting it usually means reinforcement, a three-phase supply or a flexible connection, each with a cost or a delay. Some terms in an offer are negotiable, others are fixed by the physics of the feeder.
Does a lower export limit stop me installing more panels?
A lower export limit constrains what leaves your property, not what you install. In most cases you can fit the full array and inverter and hold export to the agreed figure with a manufacturer output limit or a G100 scheme. Check whether the same offer also caps your installed generation, which is a separate figure, and note that a single-phase G99 connection tops out at 17 kW.
Does exporting from a battery count against the export limit?
Yes. A G100 export limit measures the total power leaving your property at the connection point, so it does not care whether that power came from panels or from a battery. If your battery force-exports on a peak tariff, that flow counts toward the limit, and the scheme curtails it the same way once net export would exceed the agreed figure.
Is a zero-export connection worth accepting?
It can be, if your self-consumption is high or you add storage. A zero-export connection gives up Smart Export Guarantee income, but it keeps the far larger saving from using your own solar instead of importing. Run the numbers on your own consumption before you rule it out.
Do I need G99 to fit an export-limitation device?
Export limitation is declared on the G99 application, and any external device is referenced by its number on the form. If you are export-limiting to keep a larger system within what the DNO will accept, you are already on the G99 route rather than a simple G98 notification.
The next move
Read the offer letter and find the exact export figure, any separate cap on installed generation, and the reason given for each. Ask the DNO, in writing, what constraint set the limit and which terms are open to a revised design. Then decide which of the three routes fits: accept the cap and lean on self-consumption and storage, redesign with a registered-capacity limit or a G100 scheme so the system stays under the limit by design, or pay for reinforcement or a three-phase or flexible connection if the lost export genuinely justifies it. Model the clipping with your own array data before you spend anything, because for most homes a reduced export limit costs far less than it first appears.
