Connecting Solar Panels to the Grid UK: G98, G99 and Export Payments Explained
Connecting solar panels to the grid in the UK depends mainly on inverter output, battery configuration and permitted export. Most single-phase systems at 3.68kW or below use G98 “install and notify”. Larger systems generally require G99 approval from the local Distribution Network Operator (DNO). Where full export is unavailable, G100-compliant export limiting may make a larger installation possible.
This guide explains the process for homeowners, landlords and small businesses, including batteries, paperwork and export payments.
Quick answer
To connect solar panels to the grid, your installer identifies your DNO and assesses all generation connected at the property. A fully type-tested system no larger than 16A per phase—normally 3.68kW on single phase—will usually qualify for G98 and can be installed before the DNO is notified, normally within 28 days.
A system above that limit usually needs a G99 application and written approval before commissioning. If export is restricted, a G100-compliant export-limitation scheme may be proposed.
DNO acceptance is separate from the Smart Export Guarantee (SEG): export payments also require an eligible installation, suitable metering and a contract with an export supplier.
G98, G99 and G100: which route applies?
| Route | When it normally applies | Timing | Main requirement |
|---|---|---|---|
| G98 | Fully type-tested generation up to 16A per phase: normally 3.68kW single phase or 11.04kW three phase | Usually install, then notify | Commissioning information sent to the DNO, normally within 28 days |
| G99 | Generation above 16A per phase, equipment outside G98, or many combined solar-and-storage systems | Approval normally comes first | Technical application, network assessment and commissioning evidence |
| G100 | Export must be capped below the equipment’s potential output | Included within the relevant connection process | Approved export-limitation controls and test records |
The threshold is based mainly on inverter or aggregate AC capacity, not simply the wattage printed on the panels.
A 5kWp array with a 3.68kW inverter may therefore follow a different route from a system using a 5kW inverter. Batteries capable of operating in parallel with the network must also be considered, so two small inverters are not automatically treated as one simple G98 installation.
How does a grid-connected solar system work?
Solar panels produce direct-current electricity. The inverter converts it into grid-compatible alternating current.
The property uses solar electricity first. Any shortfall is imported from the grid, while surplus electricity passes through the meter and is exported.
A standard grid-tied inverter normally shuts down during a power cut to avoid energising cables while engineers may be working. Solar panels do not therefore provide automatic backup. Backup requires a specifically designed battery system, changeover equipment and protected circuits.
The UK grid-connection process
1. Survey the property
The installer should inspect:
- The roof and mounting area
- The consumer unit
- The electricity meter
- The earthing arrangement
- The main service fuse
- Whether the supply is single or three phase
The design should also include likely future loads such as an EV charger, heat pump or home battery.
2. Identify the DNO
The DNO owns the local electricity cables, substations and network equipment. It is not necessarily the company that supplies your electricity or sends your bill.
The Energy Networks Association provides a postcode finder that identifies the relevant network operator. Northern Ireland uses NIE Networks and its G98/NI or G99/NI procedures.
3. Check the equipment and total capacity
The installer should select appropriately type-tested inverters and assess solar panels, battery storage and existing generation together.
This is particularly important when adding a battery to an existing solar installation. The solar inverter and battery inverter may both be capable of supplying electricity to the property or exporting it to the network.
An MCS-certified installer should also register the solar installation and any battery storage with the DNO.
4. Submit the correct application
A qualifying G98 system can normally be installed before the DNO notification is completed.
A G99 application should be submitted before committing to the final system design or installation date. The DNO may:
- Approve the requested connection
- Approve it with an export restriction
- Request additional technical information
- Require G100 export limiting
- Propose changes to the design
- Identify necessary network work
Do not assume that a large system will automatically receive permission to export at its full inverter capacity.
5. Install and commission the system
The completed installation must match the approved design and relevant electrical requirements.
Commissioning should cover protection settings, isolators, labels, monitoring and any export-limitation controls. Where G100 equipment is installed, the installer should also test that the system restricts export correctly if a sensor, communication link or control component fails.
6. Collect the completion documents
Ask your installer for:
- The MCS certificate, where applicable
- Electrical installation certification
- DNO acceptance or acknowledgement
- Commissioning records
- Product and workmanship warranties
- The system design and schematic
- Monitoring instructions
- The complete handover pack
Export suppliers commonly request installation certification and evidence that the DNO process has been completed.
How do batteries and export limits affect approval?
A battery can change the grid application because its inverter may be capable of exporting electricity.
The DNO assesses what the complete installation could send to the network, not simply how the homeowner intends to operate it.
A G100 export-limitation scheme measures power at the grid connection point and controls the inverter so export remains within an agreed limit.
For example, a DNO might permit a 5kW solar-and-battery system but cap export at 3.68kW. The property may still be able to consume more than 3.68kW of solar and stored electricity internally.
Export limiting can therefore allow a larger system without placing the same demand on the local network. However, it may reduce the amount of surplus electricity that can be sold at certain times.
“Zero export” does not remove the need for a DNO application. Equipment operating in parallel with the public network still needs suitable protection and approval.
Export limiting must also fail safely. A user-adjustable software setting alone may not satisfy the DNO.
Costs and timescales
| Item | Typical domestic position | Possible extra cost or delay |
|---|---|---|
| G98 notification | Usually included in the installer’s quotation | Missing type-test information, an incorrect MPAN or late paperwork |
| G99 application | Installer administration may be included or charged separately; DNO terms vary | Revised drawings, battery details or repeated submissions |
| Network work | Often no work is needed where the network accepts the export | Service, cable, phase or substation work may create a substantial site-specific charge |
| G100 limiting | Additional controls, design and commissioning | Multiple inverters, non-standard equipment or complex metering |
| SEG setup | A compatible export meter may be supplied through the energy supplier | Meter replacement, export MPAN creation or incomplete documents |
G98 is normally the quickest route because it is notification-led.
Some eligible G99 fast-track applications target a response within 10 working days. Standard assessments can take several weeks. SSEN, for example, states that quotations for installations above 3.68kW per phase and up to 50kW can take up to 45 working days.
Connection costs are site-specific. Even where the DNO prepares a quotation without charge, the customer may still have to contribute towards required network work. Obtain approval before agreeing to a fixed installation date.
A property survey is required for an accurate quotation. Possible reinforcement work cannot be priced reliably from the number of panels alone.
Can you get paid for exporting solar electricity?
In England, Scotland and Wales, the Smart Export Guarantee requires qualifying electricity suppliers to offer at least one export tariff to eligible small-scale generators.
Registration is not automatic. Rates, contract terms and eligibility checks vary between suppliers, and payments are based on measured export.
For a typical domestic solar installation, suppliers normally require MCS or equivalent certification and may request the DNO acceptance document.
You can use different companies for your import and export tariffs, although some suppliers reserve their highest export rates for customers who also buy electricity from them.
SEG applies in England, Scotland and Wales. Northern Ireland has separate export, metering and payment arrangements.
Do not size a solar system purely around export income. Electricity used in the property avoids buying power from the grid and may be more valuable than exported electricity.
Battery storage, EV charging and appliance scheduling can increase self-consumption, but the additional cost should be tested against realistic household usage.
How to choose the right grid-connected solar system
- Use real consumption data. Half-hourly smart-meter information is more useful than a generic household estimate.
- Plan for future demand. Include a possible EV, heat pump, extension, electric heating or increased home working.
- Compare inverter output, not just panel capacity. Inverter and aggregate AC capacity often determine whether G98 or G99 applies.
- Check battery power and battery capacity. Kilowatts describe how quickly the battery can charge or discharge. Kilowatt-hours describe how much electricity it stores.
- Understand the export limit. Ask whether the proposed limit is likely to curtail a meaningful amount of generation.
- Confirm compatibility and warranties. Panels, inverter, battery, monitoring platform and backup equipment should operate as one supported system.
- Request a generation estimate and system schematic. The quotation should explain its assumptions and identify the intended connection route.
- Compare long-term value. A larger panel array with sensible export control can offer better value than an undersized system, provided the roof, electricity use and budget justify it.
Most rooftop installations in England are permitted development, subject to conditions. Listed buildings, unusual panel positions and local restrictions need additional checks. Planning consent and grid approval are separate matters.
Why the installer matters
Grid approval is not an administrative afterthought.
Incorrect inverter details, omitted battery information or missing paperwork can delay commissioning, export-tariff registration and a future property sale.
A competent installer designs around the network from the beginning, submits accurate diagrams and ensures the completed installation follows the DNO offer.
Installation quality also affects:
- Electrical safety
- Roof weatherproofing
- System monitoring
- Warranty validity
- Equipment reliability
- Lifetime electricity generation
Ask who will manage the DNO application, whether amendments are included in the quotation and when you will receive the acceptance letter.
For most homeowners, an MCS-certified contractor provides the clearest route to recognised installation standards and export-tariff evidence.
Frequently asked questions (FAQs)
Clear answers about solar grid connection, G98 limits, G99 approval, inverter capacity, export restrictions, battery registration, zero-export systems, installer paperwork and MCS certification. Speak to Simple Green Energy .
Unsure which grid-connection process you need?
Speak with Simple Green Energy about inverter and panel capacity, G98 notification, G99 approval, battery storage, export limiting and the paperwork required for your proposed solar installation.
Check my connection requirementsConclusion:
Connecting solar panels to the grid UK-wide is manageable when the correct route is established before equipment is ordered.
G98 normally covers fully type-tested systems up to 16A per phase. Larger or more complex systems generally need G99 approval, while G100 may control export where local network capacity is limited.
The best design is not automatically the biggest inverter or the smallest system that avoids an application. It is the system that fits the property’s electricity demand, roof, future electrification plans and permitted export.
Book a free home survey: Simple Green Energy can assess solar potential, battery options, DNO requirements and likely export arrangements before providing a site-specific quotation.
