SSE Networks operates two electricity distribution networks in the United Kingdom. Scottish Hydro Electric Power Distribution (SHEPD) covers the North of Scotland — one of the most geographically challenging and renewable-energy-dense networks in the UK. Southern Electric Power Distribution (SEPD) covers parts of South East and South Central England, including Hampshire, Surrey, and parts of Sussex and Oxfordshire.
Both networks require G98 notification or G99 approval for solar generation connections, but the network conditions and practical challenges are very different between the two licence areas. This guide covers the G99 process for both, with particular attention to the unique characteristics of the North Scotland network.
SSE Networks: Two Licence Areas
Scottish Hydro Electric Power Distribution (SHEPD) covers:
- Highlands and Islands — Inverness, Fort William, Skye, the Western Isles, Argyll
- Northern Isles — Orkney, Shetland
- Tayside — Dundee, Perth, Angus
- Fife — Kirkcaldy, St Andrews, Dunfermline
- Aberdeenshire (parts) and Moray
Southern Electric Power Distribution (SEPD) covers:
- Hampshire — Southampton, Portsmouth, Winchester, Basingstoke
- Isle of Wight
- Parts of Surrey — East Surrey, Guildford area
- Parts of West Sussex — Chichester, Horsham area
- Parts of East Oxfordshire
Confirming Your Licence Area
SSE Networks boundary maps are available on the ssepd.co.uk website. For sites near DNO boundaries — particularly in North East Scotland near the SP Distribution boundary, or in Surrey and Sussex near UK Power Networks territory — confirm your licence area before submitting an application. Submitting to the wrong DNO delays the entire process.
SEPD: Southern Electric Power Distribution
G98 Notification (SEPD)
For systems up to 3.68 kW per phase in the SEPD area, G98 self-notification applies. Submit through the SSE connections portal within 28 days of commissioning, providing:
- Site address and MPAN
- Installed capacity in kW and kVA
- Inverter make, model, and G98 type test certificate
- Date of commissioning
- MCS certificate number (domestic installations)
- Installer qualifications and contact details
SEPD records the notification but does not issue a formal approval. Compliance with G98 technical requirements is the installer’s responsibility.
G99 Application (SEPD)
The SEPD network covers a predominantly suburban and semi-rural area. Hampshire and Surrey have significant commercial and industrial loads, which tends to mean the network has reasonable import capacity. However, the high density of residential solar already installed in parts of Hampshire and Surrey means that some distribution substations and feeders are already close to their voltage rise limits — and additional generation can be more constrained than might be expected in these areas.
SEPD network characteristics relevant to solar connections:
| Area | Network Type | Typical Connection Outlook |
|---|---|---|
| Southampton/Portsmouth urban area | Urban underground cable | Generally good capacity; faster connections |
| Hampshire rural/suburban | Mixed overhead and cable | Variable — pre-application recommended |
| Surrey (SEPD portion) | Predominantly suburban cable | Variable; some constrained areas |
| Isle of Wight | Island network, limited interconnection | Can be constrained; export limitation common |
| East Oxfordshire | Rural mixed | Pre-application recommended |
The Isle of Wight network deserves particular attention. As an island network with limited interconnection to the mainland grid, it has specific characteristics that affect generation connections. High renewable penetration relative to local demand means export capacity is constrained, and SEPD often requires export limitation for systems on the island.
Isle of Wight Connections
The Isle of Wight network is effectively islanded during normal operation. This creates specific technical challenges for generation connections — including tighter voltage management requirements and more frequent requirements for export limitation. If your project is on the Isle of Wight, factor in a pre-application enquiry and a realistic probability of an export-limited connection offer.
Required documents for SEPD G99 application:
| Document | Notes |
|---|---|
| Completed SSE G99 application form | Available on the SEPD connections portal |
| Single-line diagram | Generation system, protection, metering, and network connection point |
| Site plan | Connection point, cable route, generation equipment |
| Equipment schedule | Inverter datasheets, protection relay data |
| Protection coordination study | For larger systems or where requested by SEPD |
| Export controller confirmation | If export limitation proposed — G100-compliant AEC required |
SHEPD: Scottish Hydro Electric Power Distribution
The North Scotland Network: Context and Challenges
The North of Scotland network is unlike any other distribution network in the UK. SHEPD serves a land area of approximately 100,000 square kilometres — the largest geographic distribution network territory in Britain — with a population density that is among the lowest in Western Europe.
The network consists largely of overhead line circuits stretching across mountainous terrain, serving small communities separated by long distances. These circuits have thermal ratings that limit how much power can flow in either direction, and voltage regulation along these circuits is inherently challenging.
Against this backdrop, the North of Scotland is also the UK’s most renewable-energy-intensive area. Wind generation capacity in the Highlands alone is several gigawatts. Hydro generation is widespread. On a windy or wet day, renewable generation substantially exceeds local demand, meaning the network is in a state of export from generation to the south for much of the year. This already-high renewable penetration means that many circuits have very limited additional headroom for new generation, including solar.
Solar in North Scotland
Solar irradiance in the north of Scotland is lower than in southern England — roughly 900–1000 kWh/m² per year compared to 1050–1150 kWh/m² in Hampshire. However, the longer summer days at higher latitudes partially compensate for lower irradiance intensity, and solar can still deliver meaningful generation in the area. Using accurate irradiance data — ideally from a solar design software platform — is essential when modelling expected yields in this region.
G98 Notification (SHEPD)
G98 self-notification applies for systems below 3.68 kW per phase in the SHEPD area. The process is the same as elsewhere in the UK — notify SHEPD through the SSE connections portal within 28 days of commissioning.
For rural and island sites in the SHEPD area, G98 notification is particularly important to complete correctly, as SHEPD’s network management systems in remote areas may be less automated than urban networks, and notified installations help SHEPD manage voltage and fault management on remote feeders.
G99 Application (SHEPD)
For systems at or above 3.68 kW per phase in the SHEPD area, the G99 process requires pre-application engagement and formal approval before installation. Given the network constraints in many parts of the SHEPD area, early engagement with SHEPD’s connections team is more important here than in almost any other UK DNO area.
Identify your SSE Networks licence area and access the connections portal
Confirm whether your project is in the SHEPD (North of Scotland) or SEPD (South of England) licence area. Go to ssepd.co.uk/connections and register an account, selecting the correct licence area. For North Scotland projects, note that pre-application discussion with the SHEPD connections team is strongly recommended before submitting a formal G99 application.
SHEPD rural and island connections — specific considerations:
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Long line impedance: Rural Highland circuits have high impedance (resistance and reactance per unit length). A solar system at the end of a long feeder can cause a voltage rise that exceeds the G99 limits even at relatively modest output levels. SHEPD’s technical assessment will model this for your specific connection point.
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Fault level limitations: On very remote circuits with limited interconnection, fault level may be low. SHEPD needs to verify that generation systems will not cause protection coordination issues on these circuits.
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Island networks: Orkney and Shetland are electrically isolated from the mainland (or connected via limited subsea cables). These island networks have very high renewable penetration relative to local demand, and export capacity for new generation is extremely constrained. New solar connections on Orkney or Shetland typically require export limitation and may face significant waiting times for any available connection headroom.
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Protection requirements: SHEPD may specify specific protection settings for rural Highland connections that differ from the G99 defaults, reflecting the particular inertia and frequency characteristics of the local network section.
Submit a pre-application enquiry or full G99 application with required documents
For systems at or above 3.68 kW per phase, submit a pre-application enquiry before committing to a final design. For SHEPD rural connections especially, the pre-application response will determine whether the project is viable at the proposed location. Once the design is confirmed, submit the full G99 application with the single-line diagram, site plan, equipment schedule, and protection documentation.
SSE Connections Portal
Both SHEPD and SEPD applications are managed through the SSE connections portal at ssepd.co.uk/connections.
The portal supports:
- Account registration for contractors and designers
- Pre-application enquiries for both licence areas
- G98 notification submission
- G99 full application submission
- Document upload and version management
- Application status tracking
- Connection offer receipt and acceptance
- Commissioning documentation submission
When registering, select the correct licence area for your project. If you work across both SHEPD and SEPD, you can manage projects in both areas from a single portal account.
Pro Tip
For SHEPD applications, attach a covering note with your pre-application enquiry explaining the project context — whether it is a commercial farm building, community energy scheme, or residential property. SHEPD’s connections engineers often have local knowledge of the network in rural areas that can help them give more useful early guidance on connection feasibility and options.
SSE-Specific Technical Requirements
SSE Networks implements the ENA G99 standard with specific supplementary requirements:
Protection settings: SSE publishes specific under/over voltage and under/over frequency protection settings in its connection technical standards. For SHEPD connections in remote areas, these settings may be different from the standard G99 defaults to account for the local network characteristics.
Loss-of-mains protection: All G99 systems on the SSE network must include RoCoF (Rate of Change of Frequency) and vector shift protection settings as specified by SSE. For SHEPD island networks, the loss-of-mains detection settings are particularly important given the risk of genuine islanding on remote circuits.
Power factor and reactive power: For larger G99 systems, SSE may specify power factor or reactive power requirements in the connection offer. SEPD in particular has been active in requiring reactive power capability from commercial-scale systems in congested suburban network areas.
Metering: SSE requires metering at the point of connection for all G99 systems. The metering must record both import and export at 30-minute intervals and must be accessible for remote reading by SSE.
Commissioning test: A G99 commissioning test is required for all G99 systems. The test verifies that protection functions are operating correctly before the system is permanently connected. For SHEPD rural sites, arranging for a commissioning witness may require advance planning given travel distances. See the G99 commissioning test guide for the full test process.
Export Limitation in SSE Network Areas
Export limitation is used in both the SEPD and SHEPD networks, and is more commonly required in the SHEPD area given the high renewable penetration.
SEPD export-limited areas: The Isle of Wight, parts of rural Hampshire, and some suburban areas in Surrey where existing solar penetration is high. SEPD will identify whether export limitation is required during the pre-application or feasibility stage.
SHEPD export-limited areas: Many rural Highland circuits, Orkney, Shetland, and the Western Isles. In the most constrained areas, SHEPD may only be able to offer a connection with zero export — sometimes called a “flexible connection” — where the system can generate and self-consume but cannot export to the grid at all.
Zero Export Connections in North Scotland
In the most constrained parts of the SHEPD network, the only available connection may be on a zero-export basis. This allows on-site self-consumption but prevents any export to the grid. For commercial or farm projects where self-consumption is high relative to generation, this can still be a viable arrangement, but it significantly affects the financial case for projects designed around export revenue or Smart Export Guarantee income.
Accept the connection offer and commission in accordance with G99
SSE will issue a connection offer within 45 business days for straightforward connections. For SHEPD rural or island connections, timescales may be longer where reinforcement is required. Accept the offer in writing and pay quoted connection charges. Complete a G99 commissioning test as required and submit commissioning documentation to SSE before the system is energised.
Network Reinforcement in the SHEPD Area
When network reinforcement is required in the SHEPD area, the cost and programme can be substantially greater than for equivalent works in more densely populated UK regions. Replacing or upgrading an overhead line section in the Highlands may require specialist access, helicopter surveys, and extended construction windows that avoid winter conditions. Reinforcement programmes of 12–24 months are not uncommon for rural Highland connections that require significant network works.
This makes the pre-application feasibility stage particularly important for SHEPD projects. Understanding reinforcement requirements before committing to a site and project design avoids the situation where major capital expenditure has been committed before the true connection cost is known.
Good solar design software can model different system sizes and export profiles, allowing a project to be right-sized to the available connection capacity rather than requiring expensive reinforcement to accommodate a larger system.
Grants and Schemes for Remote Areas of North Scotland
For projects in remote parts of the SHEPD network, a range of grants and schemes may improve the economics of solar investment:
Highlands and Islands Enterprise (HIE): HIE provides business development grants and energy efficiency funding for businesses in the Highlands and Islands. Eligible projects may be able to access capital grant support towards renewable energy installations.
Community and Renewable Energy Scheme (CARES): Scotland’s CARES programme, administered by Local Energy Scotland, provides loan funding and development support for community-owned renewable energy projects. Solar is an eligible technology. CARES loans cover project development costs, which is particularly valuable in remote areas where pre-application and design costs can be higher.
Scottish Government Rural Payments: Agricultural businesses in rural Scotland may be able to access capital investment grants for on-farm renewable energy through Rural Payments and Inspections Division (RPID) schemes.
Ofgem’s Island Networks: Ofgem has specific regulatory provisions for island networks recognising their unique costs and challenges. SHEPD benefits from additional allowances for its island distribution networks, which can support investment in network capacity — but connection timescales on island networks remain longer than mainland areas.
Community Energy Routes
In remote Scottish communities, a community energy model — where local residents and businesses co-own the solar system — can access additional funding routes not available to purely commercial projects. Local Energy Scotland provides free advisory support for community energy projects and can help navigate both the funding landscape and the SHEPD connection process.
Application Timelines
| Stage | SSE Target | Notes |
|---|---|---|
| Pre-application feasibility (SEPD) | 30 business days | Suburban and rural areas |
| Pre-application feasibility (SHEPD) | 30–45 business days | Rural and island areas may be at the longer end |
| Full G99 offer (standard connection) | 45 business days | From receipt of complete application |
| Complex connection offer | 90+ business days | Reinforcement studies or major network works |
| SHEPD island connection offer | Variable | Can exceed 90 business days for constrained islands |
| G98 notification acknowledgement | No formal target | SSE records receipt; no approval issued |
Programme Planning for SHEPD
For projects in the SHEPD area — particularly on the islands or in remote Highland locations — build programme contingency into your project timeline. A connection offer requiring reinforcement can add 12–24 months to the overall project programme. Starting the pre-application process at the earliest possible stage is the single most effective action you can take to manage SHEPD programme risk.
Contact Details
SSE Connections Portal: ssepd.co.uk/connections
SEPD connections enquiries: sepd.connections@sse.com
SHEPD connections enquiries: shepd.connections@sse.com
Telephone (SEPD): 0800 048 2888
Telephone (SHEPD): 0800 048 2888
Postal address (SEPD):
Southern Electric Power Distribution plc
Connections Team
Torne House
Sherfield Park
Hook
RG27 0JU
Postal address (SHEPD):
Scottish Hydro Electric Power Distribution plc
Connections Team
Inveralmond House
200 Dunkeld Road
Perth
PH1 3AQ
Design Solar Projects Across the SSE Networks Area
SurgePV handles irradiance modelling, yield calculations, and G99 documentation for projects across the SHEPD and SEPD licence areas — including accurate generation estimates for North Scotland’s unique day-length and irradiance profile.
Book a DemoNo commitment required · 20 minutes · Live project walkthrough
Regional Compliance Resources
- Scotland solar compliance overview — planning policy, grid context, and Scottish-specific schemes
- England solar compliance overview — planning and grid context for SEPD projects
- G99 application guide — full step-by-step G99 process
- G98 vs G99 — understanding which standard applies
- G99 commissioning test guide — commissioning requirements
Other UK DNOs
- UK Power Networks — South East England, East of England, London
- NGED (National Grid Electricity Distribution) — Midlands, South West England, South Wales
- Northern Powergrid — Yorkshire, North East England
- Electricity North West — Cumbria, Lancashire, Greater Manchester, Cheshire
- SP Energy Networks — Central and Southern Scotland, Merseyside, North Wales
See the UK solar compliance hub for the complete regulatory framework.
Frequently Asked Questions
What are the two SSE Networks licence areas and what do they cover?
SSE Networks holds two distribution licences. Scottish Hydro Electric Power Distribution (SHEPD) covers the North of Scotland, including the Highlands, Islands, Orkney, Shetland, Tayside, and Fife. Southern Electric Power Distribution (SEPD) covers parts of South East and South Central England, including Hampshire, the Isle of Wight, parts of Surrey, West Sussex, and East Oxfordshire.
Why is connecting solar to the North Scotland network more complex than other UK areas?
The North of Scotland network faces several challenges that make generation connections more complex. The network serves a large, sparsely populated area through long overhead line circuits with limited thermal capacity. Renewable penetration is already high — the area has significant wind and hydro generation — which means many circuits are constrained and have limited additional headroom for solar. Remote areas may also lack the voltage regulation infrastructure to accommodate additional generation without significant reinforcement.
What is the SSE connections portal and how do I access it?
SSE Networks uses an online connections portal to manage G98 notifications and G99 applications for both SHEPD and SEPD licence areas. The portal is accessible at ssepd.co.uk/connections. You register as a contractor or designer, select the relevant licence area, and submit applications with supporting documentation through the portal.
Are there grants or schemes available for solar in remote areas of North Scotland?
Yes. The Highlands and Islands have access to specific funding through Highlands and Islands Enterprise (HIE) and through community energy funding schemes including the Scottish Government’s Community and Renewable Energy Scheme (CARES). These are available to community projects and some commercial projects in remote areas. The Rural Support framework and the Islands Connectivity Plan also include elements relevant to energy costs in island communities.
