Scotland's two network operators
Your electricity supplier sends the bills. The cables that bring power down your street belong to a different company, the distribution network operator. Scotland has two of them. SP Energy Networks, through SP Distribution plc, runs the network across central and southern Scotland (SP Energy Networks). SSEN, through Scottish Hydro Electric Power Distribution plc, runs it across the north of Scotland (SSEN).
You do not choose your operator, and switching supplier does not change it. Geography decides. Glasgow, Edinburgh and Dumfries, for example, sit on the SP Energy Networks side, while Inverness, Aberdeen and the islands of Orkney, Shetland and the Western Isles are on SSEN's network. If you are unsure, your supplier can tell you, and the long supply number printed on your bill, the MPAN, identifies the network company too.
| Operator | Licensed company | Area served | Examples | Where to read its rules |
|---|---|---|---|---|
| SP Energy Networks | SP Distribution plc | Central and southern Scotland | Glasgow, Edinburgh, Dumfries | Connecting solar: who to inform |
| SSEN | Scottish Hydro Electric Power Distribution plc | North of Scotland | Inverness, Aberdeen, Orkney, Shetland, the Western Isles | Micro-generation connections |
Places are examples only. For an address near the boundary, check with your supplier or the operator.
The operator matters for solar because any generator connected to its network has to be either reported to it or agreed with it in advance. A home solar system counts as a generator. So does a battery that can send power back out. With roughly 198,000 Scottish homes already carrying panels, about 8% of the housing stock (Scottish House Condition Survey 2024), operators need an accurate record of where that generation sits so they can keep local voltages within safe limits.
Small systems: connect first, then notify (G98)
Most home systems connect under an engineering standard called G98. It covers small, type-tested generators up to 16 A per phase. On a single-phase supply, the usual arrangement in a house, that works out at 3.68 kW (SSEN).
In practice the limit applies to the inverter, the unit that turns the panels' direct current into the alternating current your home runs on. It does not apply to the panels' combined rating on paper. A roof with a little more panel capacity than the inverter's rating can still fall under G98, because the inverter caps what it delivers. Ask the firm quoting which figure its design works to, and get it in writing.
Under G98 the order is simple. The system is connected first, then the operator is told, using its own forms (SSEN forms; SP Energy Networks). There is normally no waiting for permission. SSEN says the firm arranging the connection usually contacts it on the householder's behalf, though you can do it yourself (SSEN). Ask for a copy of the notification and keep it with your MCS certificate. You will need both if you sign up for export payments or sell the house.
On a three-phase supply, the limit applies to each phase separately, so a larger system can still come within G98 if its output is spread evenly across the phases. Three-phase supplies are unusual in homes. The firm quoting can check yours from the meter cupboard.
Bigger systems and batteries: apply first (G99)
Anything over the G98 limit falls under G99, and the order flips. The application goes to the operator before connection, and the system is not switched on until the operator has agreed (SSEN). The operator can accept it as it stands, accept it with a cap on export, or say the local network needs work first. That last answer can add time and cost, and it is the reason to apply early.
In homes, batteries are the usual trigger. A battery either has its own inverter or shares a hybrid one, and the operator looks at everything on site that could feed the network at the same moment. Panels whose inverter sits at the G98 limit, plus a battery inverter, can push a home over it even though the panels alone would have fitted.
SSEN describes a fast-track G99 route for single-phase homes, where a G100 export-limiting device holds total export at 3.68 kW, and it lists battery storage beside solar as a source of generation (SSEN). It also lists a route for small systems spread across more than one property, which can matter for a block of flats. SP Energy Networks publishes its own guidance on who must be told about solar and wind generation (SP Energy Networks).
If you might add a battery later, mention it at the start. A battery fitted afterwards changes the generation on site, and the operator has to know about it. The battery guide covers sizes and what Scottish households pay for them.
| Question | G98 | G99 |
|---|---|---|
| Which systems? | Small type-tested systems within 16 A per phase (3.68 kW single-phase) | Anything larger, including many solar plus battery set-ups |
| When is the operator involved? | Told after connection | Applied to before connection |
| Can the operator say no or set conditions? | Not normally; it is a notification | Yes: it can approve, approve with an export limit, or require network work |
| Who sends the forms? | Usually the firm fitting the system | Usually the firm fitting the system, before work starts |
| What should you keep? | A copy of the notification | The operator's written agreement and any export limit it sets |
Based on SSEN's micro-generation guidance and its G98 and G99 documents. SP Energy Networks applies the same national standards.
Export limitation in plain words
An export limit is a ceiling on how much power your home can send onto the network at any one moment. It does not cap how much the panels produce, and it does not cap what you use indoors.
A small control device measures the power flowing at the point where the supply enters the house. When the panels are making plenty and the house is using little, it tells the inverter to hold export at the agreed level. Anything above that is used in the home, sent to a battery, or simply not produced for those minutes.
How much output that loses depends on how often your export would have pushed past the ceiling. In Scotland those moments bunch together in late spring and summer, when long days give the most power. A well-angled Aberdeen roof makes 120 kWh per kW in May, against 24 in December (PVGIS 5.3). In winter an export limit rarely comes into play at all.
An export limit is often what allows a bigger system, or a battery, onto a network that could not take unlimited export from every house on the street. Seen that way, it is a trade: you give up a little summer output at the margin, and you get a connection the operator will accept.
What to ask the firm quoting your system
Most of this is handled by the firm that fits the system. You still need to know what it has done in your name. Ask:
- Which operator serves the address, and which route applies: G98, fast-track G99 or a full G99 application?
- What is the inverter rating, and with any battery included, does the total go over 3.68 kW per phase?
- Who sends the notification or application, and when? Will you get a copy?
- If G99 applies, is the quote conditional on the operator's approval, and what happens if it asks for an export limit or network work?
- Is the supply single-phase or three-phase, and are the main fuse and consumer unit up to the job?
- For a flat, whose supply will the system connect to, and who owns the roof it sits on?
Keep the answers with the quote. The guide to choosing an installer covers MCS certification and how to compare quotes line by line. For flats, the tenements and flats guide explains roof ownership under Scots law, and the export payments guide explains what happens to the power that leaves the house.