Export Limitation for Solar Panels UK: G100, Zero-Export & What It Costs You

Most homeowners assume that once solar panels are on the roof, every spare watt gets sold back to the grid. For a growing number of UK installations, that isn't quite true. If the local electricity network can't safely absorb everything a system could generate, the Distribution Network Operator (DNO) can require export limitation — a cap, or in some cases a complete block, on how much power the installation is allowed to push onto the grid.

Why DNOs impose export limitation

Local electricity networks were built decades ago around one-way power flow: from substation to home. Rooftop solar reverses that on sunny afternoons, and on streets with thin cabling, an old transformer, or a lot of nearby solar already connected, a large new system can push voltage on that local circuit above safe limits. Rather than refuse the connection outright — or force an expensive network reinforcement that can take months and cost thousands — many DNOs offer export limitation as a condition of connection. You get connected quickly; in exchange, your system's export is capped at a level the local network can handle, which is sometimes zero.

This is most common in rural areas with long, thin low-voltage feeders, on streets that already have several solar installations, and for larger systems (typically anything pushing past the standard single-phase threshold) applying under G99 rather than the simpler G98 notification route. See our G98 notification guide for where that line sits.

How export limitation actually works: the G100 standard

Export limitation schemes in Great Britain follow Engineering Recommendation G100, published by the Energy Networks Association (ENA). A compliant scheme has three parts: a meter at the property's grid connection point that continuously measures the power flowing in and out, a controller that reads that measurement, and a link from the controller to your inverter (and battery, if fitted) that commands it to throttle output the moment exports approach the agreed limit. Crucially, G100 requires the system to be fail-safe — if the limiting device itself loses communication or power, the inverter must cut its own export rather than default to unrestricted generation.

A zero-export device is simply the strictest version of this: the agreed export capacity is set to 0kW. Your panels can still generate and you still get free electricity for anything you use in the house at that moment, but nothing is allowed to spill onto the grid — any surplus that isn't self-consumed or stored is curtailed (wasted) rather than exported.

What it means for your Smart Export Guarantee income

Export limitation directly affects what you can earn from the Smart Export Guarantee (SEG). SEG only pays for electricity you actually export, so a hard cap — and especially a zero-export setting — reduces or removes that income stream even though your system is generating normally. This is the single biggest reason it's worth checking with your installer, before you sign a contract, whether your postcode is likely to need it: a system sized for maximum export potential is far less valuable if the DNO caps what you can actually sell.

The practical fix is to shift consumption to match generation rather than rely on export income. A home battery soaks up surplus generation instead of letting it hit the export limit and get curtailed, and a solar diverter can route spare power into your hot water cylinder or an EV charger instead. Both effectively convert generation that would otherwise be wasted (or capped) into a bill saving, even under a zero-export condition.

What to do if your DNO applies export limitation

Your installer will find out whether limitation applies as part of the G98/G99 application — it isn't something you can choose to skip. If you're quoted a limited or zero-export connection, it's worth asking your installer three things: whether a battery or diverter would let you use most of the otherwise-curtailed generation, whether the DNO has indicated any timeline for network reinforcement in your area that might lift the limit later, and whether a smaller system without limitation would actually produce more usable, exportable energy than a larger one that's capped. None of these questions have a single right answer — it depends on your roof, your usage pattern, and your local network — but asking them before installation avoids an unpleasant surprise on your first SEG statement.