How selling spare power works in Scotland
Electricity your panels make but the house does not use flows out to the local network. In Scotland, as in England and Wales, the arrangement that lets a household sell that surplus to an electricity supplier is known as the Smart Export Guarantee (SEG), a set of rules overseen by Ofgem (Ofgem).
Under SEG, some suppliers, which Ofgem calls SEG Licensees, have to offer an export tariff to small generators like home solar, and the rate must always be above zero. Every licensed supplier declares each year whether it is in that group. Everything beyond that floor, the rate, the contract length and the other terms, is for each supplier to decide (Ofgem). GOV.UK confirms the scheme applies in England, Scotland and Wales (GOV.UK).
Export payments are for electricity, not equipment. Nobody hands you money towards the system; you are paid per kWh, and only once it is running. Households in Scotland who can afford panels get no grant for solar PV; the guide to solar panel grants in Scotland explains the narrow routes that remain for those who qualify. When the panels fall short, you keep buying from the grid on whatever import tariff you already have.
What you need before you sign up
Four things, and the first two are fixed by the scheme rules:
- A certified system. GOV.UK says the installation and the installer must be certified through MCS or an equivalent scheme (GOV.UK). For solar up to 50 kW, which covers any home roof, that means MCS. The MCS website has a search where you can confirm a firm's certification.
- A meter that can measure export. GOV.UK says you need a meter capable of half-hourly export readings, which usually means a smart meter. Check with your supplier that yours has been configured to log exported kWh.
- The grid paperwork. A G98 notification or G99 agreement with SP Energy Networks or SSEN. The grid connection guide explains which applies.
- A tariff you have chosen. Signing up is your job: pick a supplier's tariff and send in your MCS certificate and meter details.
Older systems on the Feed-in Tariffs
Some Scottish roofs still carry systems registered for the old Feed-in Tariffs. GOV.UK says a system already receiving export payments under the Feed-in Tariffs cannot also take a SEG tariff (GOV.UK). If you add new panels to a house that has an older system, ask how the two will be metered and which scheme each part falls under before work starts.
Comparing tariffs when no rate is quoted
This guide does not print an export rate, and treats any page that names "the" Scottish rate with care. Rates differ between suppliers and move over time. A figure that was right on the day it was written can be wrong a month later. Look up live offers when you are ready, and note the date.
The pence per kWh is only part of the comparison. The table sets out what else to check.
| Check | Why it matters |
|---|---|
| Fixed or variable rate | Variable rates move whenever the supplier decides; fixed rates hold only until their term ends. |
| Open to anyone, or only to the supplier's customers | The scheme does not require your export and import suppliers to match, but some tariffs do. |
| Contract length and notice | Check how easily you can move to another export supplier later. |
| How readings are taken | Payments are based on export meter readings, so the smart meter must be sending them. |
| How and when you are paid | Bill credit or bank transfer, monthly or quarterly: it affects how easily you can track what the panels earn. |
| Links to an import tariff | The best export offer can come tied to an import tariff that suits you less. Compare the pair. |
Scheme rules from Ofgem and GOV.UK. Individual tariff terms come from each supplier.
How many kWh a Scottish roof might send out
Daily routine, more than panel size, sets how much leaves the house. Whatever the system makes while the house is using little goes out to the network.
Start with a full year. Use the Energy Saving Trust figure for a typical home system, 4.5 kWp, mounted on a south-facing roof at a typical pitch. PVGIS gives its yearly output in each place (PVGIS 5.3). Set that against Ofgem's typical household use of 2,500 kWh a year (Ofgem).
| Place | Panels make in a year | More than typical yearly use by | Share of output that must leave the house, at least |
|---|---|---|---|
| Dundee | 4,200 | 1,700 | 41% |
| Edinburgh | 4,050 | 1,550 | 38% |
| Aberdeen | 4,000 | 1,500 | 38% |
| Glasgow | 3,850 | 1,350 | 35% |
| Inverness | 3,650 | 1,150 | 31% |
| Lerwick | 3,450 | 950 | 27% |
| Fort William | 3,050 | 550 | 18% |
Output from PVGIS 5.3 for a 35-degree south-facing roof, multiplied by the system size; use from Ofgem. Figures rounded to the nearest 50 kWh.
In every place shown, a typical system makes more in a year than a typical home uses. The gap is the least that could possibly be exported, because it assumes every kWh the house uses comes from the roof. That never happens: the panels make nothing at night, little on winter afternoons, and the house uses power at both. In practice the true figure sits well above the table.
A single day makes the point. By our arithmetic from PVGIS, that system at the best angle in Dundee makes about 17 kWh on an average June day, roughly 2.5 times the 6.8 kWh a typical home uses in a day. On an average December day it makes about 3.5 kWh, less than the house needs. Summer drives exports in Scotland; winter barely produces any.
Roof direction and the timing of exports
Direction changes when the surplus appears, not just how much there is. A south-facing roof peaks around midday, when many homes are quiet. An east roof front-loads the morning, and a west roof leans into the late afternoon and early evening, when cooking and lighting start. In Glasgow, PVGIS gives a south-facing pitched roof 853 kWh per kW a year, against 673 facing east and 683 facing west (PVGIS 5.3). The west roof makes less in total, but more of what it makes can land while the household is using power. Some homes split panels across east and west slopes for that reason, spreading output across the day instead of piling it up at noon.
Every home's sum is different. A smaller array, an east or west roof, or a household home all day will export less. A large array on an empty house will export more. The yield-by-place page gives output by direction and pitch, so you can redo the sum with your own roof and your own bill.
Using more of your own power instead
Every kWh you use at home is one you do not have to buy, so most households try to use more of their own output before worrying about export rates. A few ways to shift use into daylight:
- Run the washing machine, dishwasher and tumble dryer late in the morning or early in the afternoon, especially from April to September.
- Charge an electric car at home on bright days, if you are home to do it.
- Use a device that sends surplus power to the hot water cylinder's immersion heater rather than out to the network.
- Add a battery to carry daytime surplus into the evening. The battery guide covers sizes and prices in Scotland.
Storage can also move you onto a different grid route: when the combined inverter output passes 3.68 kW on a single-phase supply, the operator's prior agreement is needed and an export cap may follow. A heat pump changes the picture the other way, adding winter demand when panels make least; the guide to solar with a heat pump follows that through a Scottish year.