Solar Panel DNO Application UK: G98, G99 and G100 Explained
A solar panel DNO application registers or obtains approval for a grid-connected solar PV system with the local Distribution Network Operator. The correct route depends mainly on the system’s maximum AC output per phase, including battery inverters—not simply the total wattage of the solar panels.
For most single-phase homes in Great Britain, systems up to 3.68 kW AC normally follow G98 and can be installed before the DNO is notified. Systems above 3.68 kW per phase normally require G99 approval before installation. Where the DNO cannot accept the proposed export, a G100-compliant limitation scheme may allow a larger system while controlling how much power reaches the grid.
This guide explains the rules, process, costs, timescales and questions homeowners, landlords, EV owners and businesses should ask before accepting a solar quote.
Quick answer
A property with grid-connected solar must be registered with its Distribution Network Operator. In Great Britain, G98 usually applies where total generation is no more than 16 amps per phase—3.68 kW on a single-phase supply—and the installer normally notifies the DNO within 28 days of commissioning. G99 applies above that limit and requires agreement before installation. Battery inverters and existing generation can count towards the total. G100 applies where an approved control system limits export. A competent installer should calculate the capacity, submit the paperwork and provide the final DNO acceptance evidence.
| Route | When it normally applies | Timing | What to expect |
|---|---|---|---|
| G98 | Up to 16 A per phase, normally 3.68 kW AC on single phase | Install first, notify afterwards | Installer registers the commissioned system within 28 days |
| G99 | Above 16 A per phase or outside the G98 conditions | Apply and obtain agreement before installation | DNO may approve, restrict export, request changes or quote for network work |
| G100 | Export must be capped through a compliant control scheme | Assessed with the relevant connection route | Larger installed capacity may be possible, but export is limited |
What is a solar panel DNO application?
The DNO operates the local electricity cables, substations and other infrastructure carrying power to and from your property. It is separate from the electricity supplier that bills you. Because solar panels can send electricity into the local network, the DNO needs accurate technical information to maintain safe network operation.
You can identify your operator using the Energy Networks Association postcode checker. An MCS-certified solar contractor should normally manage the application or notification for you.
G98, G99 or G100: which do you need?
G98: smaller, type-tested systems
G98 is the usual “connect and notify” route for fully type-tested microgenerators up to 16 A per phase. On a typical single-phase home supply, this equals 3.68 kW AC. The system can generally be commissioned before notification, provided it meets the G98 conditions, and the DNO is then notified within 28 days.
The key figure is registered AC generating capacity. A panel array above 3.68 kWp may still use G98 if its compliant inverter output is permanently limited to 3.68 kW. Conversely, multiple inverters could require G99 if their combined AC output exceeds the limit.
This means a 4 kWp or 5 kWp solar array does not automatically require G99. Your installer must examine the inverter rating and the complete system design rather than panel wattage alone.
G99: larger or more complex installations
G99 applies when aggregate generation exceeds 16 A per phase or otherwise falls outside G98. The DNO assesses the proposal before installation. The submission commonly includes:
- The property’s MPAN and supply details
- Solar and battery inverter models
- ENA type-test references
- A single-line electrical diagram
- Protection information
- The requested export capacity
The DNO may approve the full request, approve a lower export level, request design changes or require network work. Written acceptance should be obtained before a G99 installation is connected.
Some regions operate automated approval processes. For example, UK Power Networks may automatically approve qualifying domestic installations with maximum export below 5 kW. This is a regional process, not a national increase in the G98 threshold, so the correct application must still be submitted.
G100: controlling export
G100 is not a substitute for G99. It covers customer export or import limitation schemes. A compliant system monitors electricity flowing through the grid connection and prevents export exceeding the agreed level.
This can help where the roof supports a larger array and an EV, battery or high daytime demand can use the energy, but the local network cannot accept the system’s full potential export.
For example, a property might have a 6 kW inverter but an approved export limit of 3.68 kW. The household can still use more than 3.68 kW directly when solar production and demand coincide, while the limitation equipment prevents excess power being exported.
The DNO application process
- Survey the property. Confirm the supply phase, main fuse, existing generation, roof capacity and planned batteries, heat pumps or EV charging.
- Design from AC capacity. Distinguish panel capacity in kWp from inverter output in kW and aggregate every device capable of generating onto the AC system.
- Check equipment compliance. Use suitable inverters and protection equipment with relevant ENA type-test records. Non-type-tested equipment may require additional evidence.
- Choose the route. G98 is normally notified after commissioning; G99 must usually be accepted first. Some integrated solar-and-storage systems may qualify for a simplified or fast-track G99 route.
- Submit complete documents. Incorrect MPANs, capacities, diagrams or equipment references can delay assessment.
- Review the DNO decision. Check the approved inverter capacity, export limit and conditions against the system described in your quotation.
- Install and close out. The installer commissions the equipment, tests any export-limitation scheme and submits the required completion documents.
- Keep the evidence. Retain the DNO acceptance letter, MCS certificate, electrical certificates, warranties and export-limit settings. Export tariff providers may request evidence that the installation has been registered and accepted.
DNO application costs and timescales
| Item | Typical homeowner position | What can change it |
|---|---|---|
| G98 administration | Commonly included in the installation quote | Remedial registration for an altered or unregistered system |
| G99 application | May be included or separately itemised | DNO policy, system size and technical assessment |
| Assessment time | G98 is post-install; standard G99 can take several weeks | Missing documents, workload, local constraints or network studies |
| Export limitation | Extra equipment or commissioning may be required | Inverter compatibility and approved export level |
| Network upgrade | No DNO work may mean no network charge | Service cable, phase upgrade, transformer or local network capacity |
There is no universal G99 application price. Some domestic applications progress without a direct DNO charge, while others attract assessment, connection-offer, testing or reinforcement costs.
UK Power Networks states that customers normally pay no network charge where no electricity-supply upgrade is required. Other operators may charge connection-offer expenses for applications requiring detailed design or assessment.
Your quotation should therefore confirm:
- Who pays any DNO application fee
- Whether installer administration is included
- Whether resubmissions or revised designs are included
- Who pays for export-limitation equipment
- What happens if less export is approved
- Whether network-upgrade costs require separate approval
Allow several weeks for standard G99 planning and avoid booking an installation around an assumed approval date. Eligible fast-track solar-and-storage applications may receive a faster decision, while constrained networks or incomplete submissions can take longer. ENA guidance describes a standard 45-day process and a simplified battery route intended to reduce eligible cases to ten days or less, although actual handling can vary.
An accurate quotation may require a property survey and DNO assessment.
What happens if the DNO limits your export?
An export limit is not automatically a reason to reject solar. Its financial effect depends on:
- Solar array size
- Daytime electricity consumption
- Battery capacity
- EV charging habits
- Seasonal generation
- The approved export limit
- The available export tariff
A home using significant electricity during daylight hours may rarely reach the export cap. A low-use property without battery storage may lose more potential export.
Ask the installer for an annual performance simulation showing estimated generation, household self-consumption, battery charging, curtailed energy and export income under the proposed limit. This is more useful than comparing panel numbers alone.
Do not confuse inverter capacity with export capacity. A system may have a larger inverter while a G100 controller restricts the power exported to the grid.
A “zero-export” design still requires proper DNO engagement. It is not permission to connect generating equipment without registration.
Batteries, three-phase supplies and later upgrades
Battery storage can change the application route because the aggregate AC capacity may include both solar and battery inverters. Separate devices can push a property over the G98 threshold even when each inverter is individually below it.
Some integrated solar-and-storage installations can use a simplified G99 process where:
- The equipment is appropriately type-tested
- Solar and battery capacities remain within the relevant limits
- A compliant export-limitation scheme is installed
- Export is restricted to the approved capacity
The installer must confirm that every eligibility condition is satisfied.
Three-phase properties have a per-phase threshold, so a balanced installation may support more total capacity than a single-phase home. Phase balance, inverter configuration and the property’s existing connection must still be checked.
Adding a battery, replacing an inverter or expanding an existing array may require a fresh application or updated notification. Tell your installer about every existing generator at the property. A new G99 application is required where a modification increases aggregate capacity above 16 A per phase.
How to choose the right solar and DNO proposal
- Ask for both panel capacity in kWp and maximum AC inverter output.
- Confirm whether the property has a single-phase or three-phase supply.
- Request the proposed grid-export capacity.
- Check whether battery inverters and existing generation have been included.
- Ask whether the route is G98, standard G99, simplified G99 or G99 with G100.
- Confirm that applications, revisions and final acceptance documents are included.
- Compare savings forecasts using the approved export limit.
- Make the contract conditional on a workable DNO outcome where approval remains pending.
Be cautious if an installer recommends a 3.68 kW inverter solely to avoid the G99 process without comparing the output and savings of a larger design. The simplest application is not always the best long-term system.
Why the installer matters
DNO approval depends on a consistent technical design. Incorrect capacity calculations, mismatched equipment references, incomplete diagrams or an unsuitable export-limitation scheme can cause delays and redesigns.
Installation quality also affects:
- System safety
- Solar generation
- Battery operation
- Export-limit accuracy
- Equipment warranties
- Long-term reliability
- Future expansion options
MCS installation standards require the contractor to complete the appropriate G98 or G99 notification process.
A capable installer should explain the route before you sign, manage communication with the DNO, design around realistic household demand, commission the equipment correctly and hand over all acceptance evidence.
Is a G99 solar system worth it?
Often, yes—particularly for homes with an EV, heat pump, battery or high daytime electricity use. A larger G99 system can offer better long-term value than restricting the design to 3.68 kW purely to avoid paperwork.
However, a larger system is not automatically better. If the DNO imposes a low export cap and the property cannot consume or store the surplus, extra panels may provide diminishing returns.
Ask the installer to compare:
- The best G98-compatible system
- The full G99 system requested
- The system under the likely export limit
- A G99/G100 design with battery storage
Every option should use the same assumptions for generation, electricity prices, degradation, maintenance and export tariffs.
Frequently asked questions (FAQs)
Clear answers about DNO registration, electricity suppliers, G98 notifications, G99 approval, inverter capacity, battery output, G100 export limits and zero-export solar systems. Speak to Simple Green Energy .
Unsure which DNO process your solar system needs?
Speak with Simple Green Energy about inverter capacity, battery storage, G98 notification, G99 approval, export limits and the network requirements for your proposed installation.
Check my DNO requirementsConclusion:
The central question is whether total AC generation stays within 16 A per phase. In Great Britain, G98 normally allows installation followed by notification; G99 requires approval before installation; and G100 can control export where the network cannot accept the full output.
Choose a proposal based on a proper survey, accurate solar-and-battery capacity, type-tested equipment, transparent DNO costs and a financial forecast using the approved export limit.
Book a free home survey with Simple Green Energy for a solar design, savings estimate and DNO route assessment before committing to an installation.
