What the SEG is, and what it is not
The SEG is a rule for electricity suppliers, overseen by Ofgem. Licensed suppliers above a set size must offer at least one export tariff to small generators such as home solar, and the rate must be more than zero (Ofgem; GOV.UK). Beyond that floor, the rate and the terms are up to each supplier.
It pays for electricity, not for panels. It is not a grant, a loan or a discount on the installation. The household pays for the system, then is paid per kWh for whatever leaves the house unused. Electricity you buy is still billed at your normal import tariff whenever the panels fall short.
That distinction matters because doorstep "solar grant" offers often blur the two. If you can afford panels, no grant will cover them, anywhere in England. The one local grant that can include panels is GMCA's Warm Homes: Local Grant. It is limited to owner-occupied homes at EPC D to G and privately rented homes at D or E, where the household qualifies through a route such as a means-tested benefit or income below £36,000 (GMCA). The funding guide covers that scheme in full.
What you need before a supplier will pay
- MCS certification. Any system up to 50 kW, which takes in every home roof, has to be certified under MCS (Ofgem). Check the firm on the MCS installer search before you sign. A system fitted without certification cannot join.
- A meter that records exports. Export tariffs pay on metered readings, so the meter must measure what leaves the house. A smart meter that can record export is the usual route; ask your supplier to confirm it is set up for that.
- A tariff you have signed up to. Nothing is paid automatically. You choose a tariff and apply, usually with the MCS certificate and the meter details to hand.
- The grid paperwork. Keep the G98 notification or G99 agreement with the certificates. The grid connection guide explains which one you should have.
Moving into a home that already has panels
Plenty of Manchester buyers inherit a system. The seller's export contract does not pass to you automatically, so you will need a tariff in your own name. Before completion, ask the seller for the MCS certificate, the inverter and meter details, the grid paperwork and any warranty documents. Without the MCS certificate a supplier is unlikely to sign you up, so treat it as part of the sale.
An installer may offer to sort out the export tariff for you. That is fine, but the contract is still between you and the supplier, so read its terms yourself before you agree.
Rates and terms: why this page names no rate
Each supplier sets its own SEG rate and conditions, and they change. Some fix a rate for a period; others vary it. A figure presented as "the" export rate is one tariff on one date, so this guide does not print one. Compare live offers yourself, and write down the date you looked.
When you compare, look past the pence per kWh:
- Fixed or variable. A variable rate can fall as well as rise; a fixed one may end after a set period.
- Tied to your import supply. Ask whether the tariff is open only to customers who also buy their electricity from that supplier.
- Leaving. Check whether you can switch export supplier later, and how much notice you must give.
- Meter readings. Confirm that readings come automatically from the smart meter rather than from you.
- How you are paid. Ask whether the money arrives as bill credit or into a bank account, and how often.
The best tariff on paper may not suit a household that also wants a particular import tariff. Look at the two together.
How much a Manchester home might export
How much you export depends far more on when you use electricity than on the panels. Exports are whatever the panels make that the house is not using at that moment.
Take one worked example. Start with a system of 4.5 kWp, the size the Energy Saving Trust treats as typical for a home. PVGIS gives the best-placed central Manchester roof 888 kWh per kW over a year (PVGIS), so that system would make about 4,000 kWh a year. Ofgem's typical household uses 2,500 kWh of electricity a year (Ofgem).
The table spreads that typical use evenly across the year, about 208 kWh a month, and sets it against the system's monthly output. In any month where the panels make more than the house uses in total, the difference cannot all be used at home without a battery. It has to be exported.
| Month | Panels make | Typical use, spread evenly | Must be exported, at least |
|---|---|---|---|
| January | 126 | 208 | 0 |
| February | 207 | 208 | 0 |
| March | 356 | 208 | 147 |
| April | 473 | 208 | 264 |
| May | 504 | 208 | 296 |
| June | 491 | 208 | 282 |
| July | 477 | 208 | 269 |
| August | 432 | 208 | 224 |
| September | 365 | 208 | 156 |
| October | 261 | 208 | 53 |
| November | 176 | 208 | 0 |
| December | 135 | 208 | 0 |
Output from PVGIS 5.3 monthly figures for the best-placed roof; use from Ofgem's typical consumption, divided by twelve. Real use is not even through the year.
On these assumptions, at least 1,700 kWh a year would leave the house, about 42% of what the panels make, by our arithmetic from PVGIS and Ofgem figures. That is a floor, not a forecast. Real exports are higher, because the panels make nothing at night and evening use cannot be met from the roof without storage.
The months tell the same story. From March to October, this system makes more than the household uses in the whole month. In the other months it makes less, and most of what it produces is used at home.
Your own figure will differ. A smaller array on a terrace in Moss Side outstrips the household's use in fewer months. A home that is empty all day exports more of its summer output. An east or west roof shifts output towards the morning or the evening. The roof yield explorer gives monthly kWh for your direction and pitch.
You can redo the sum for your own home in a few minutes. Your bills show the electricity you use in a year, in kWh. Divide it by twelve, then set it against the monthly output the explorer gives for your roof and system size. Wherever output is higher than use, the gap is the least you would export that month. If your use is well above Ofgem's typical figure, perhaps because of an electric car or electric heating, the floor drops; if it is lower, the floor rises.
What a battery changes
A battery shifts the split between exported and used kWh. Instead of sending the afternoon's surplus to the grid, the system stores it and the house draws on it after dark. Exports fall, and more of the solar output is used at home.
How far exports fall depends on the battery's size and on evening use. On a bright Manchester summer day a battery may be full by early afternoon, and the rest is exported anyway. In midwinter the panels seldom make a surplus to store. So a battery changes the spring, summer and early autumn evenings most.
Before buying one mainly to cut exports, look at your own pattern. A household that is out all day and busy in the evening has the most surplus to move. One that already uses most of its output in daylight has less, and a battery will spend more of the year part-empty.
It can change the grid route too. If the solar and battery inverters together go above 3.68 kW on a single-phase supply, the system needs a G99 application before connection, and the operator may set an export limit. The battery guide covers sizes and costs, and the cost guide shows what North West homes paid for panels.