If you’ve got solar panels and you’re switching energy supplier, there’s one job that trips up more homeowners than anything else: sorting out your export payments. It isn’t automatic. Your new supplier can happily start billing you for imported electricity from day one, while your Smart Export Guarantee (SEG) payments quietly stop — because nobody told the new supplier you generate power too. This guide walks through exactly what to do, in what order, so you don’t lose weeks (or months) of export income during the switch.
Why solar changes the switching process
For a non-solar household, switching supplier is simple: compare tariffs, click switch, done. Add solar panels and you’re really managing two separate relationships — one for the electricity you import from the grid, and one for the electricity you export back to it. These don’t have to be with the same company, and increasingly they aren’t, because the best import tariff and the best SEG export rate rarely come from the same supplier.
The Smart Export Guarantee is the scheme that replaced the old Feed-in Tariff for anyone who installed solar after March 2019 (and FiT households moving to smart export too). Under SEG, licensed suppliers must offer something for exported electricity, but the rate is entirely commercial — there’s no fixed national price. In practice you’ll see anything from a token 1-2p/kWh on a basic tariff up to around 12-20p/kWh on the better SEG products, so shopping around genuinely matters. This is also why so many households run an import supplier and an export supplier that are different companies entirely.
The import/export split, explained
When you switch, you need to think about these as two separate actions:
Import switch — this is the “normal” energy switch everyone’s used to: moving your day-to-day electricity (and gas, if applicable) supply to a new tariff. It’s triggered the same way it always has been — compare, apply, wait for the switch date, and your old import contract ends automatically.
Export switch (SEG) — this is not automatic and does not happen as a side-effect of switching your import supplier. SEG is a separate contract you apply for directly with a supplier of your choosing, submitted with your own paperwork. If you don’t proactively apply to a new SEG supplier, you can end up with no export contract at all — generating electricity for the grid for free, or effectively for nothing, until you sort it out.
A common and perfectly legitimate setup: import from Supplier A because they have the cheapest standing charge and unit rate, export to Supplier B because they pay the best SEG rate. Nothing wrong with that, provided both contracts are live and neither has silently lapsed.
Step-by-step: switching without losing your SEG income
1. Check your current SEG contract terms before you do anything else. Most SEG tariffs run for a fixed term (commonly 12 months) and many auto-renew unless you act. Log into your current SEG supplier’s portal and check the renewal date and notice period.
2. Compare SEG rates separately from import tariffs. Don’t assume your existing supplier’s SEG rate is competitive just because their import tariff is. Some suppliers pay well over the odds for export to attract solar customers even if their import price is mid-table; others do the reverse. Treat them as two separate comparisons.
3. Gather your paperwork before applying anywhere. Every SEG application needs:
- Your MCS certificate (Microgeneration Certification Scheme) — proof your installation was fitted and commissioned by a certified installer to the required standard. Without a valid MCS certificate, no licensed supplier can register you for SEG, full stop.
- Your MPAN (meter point number, the long reference on your electricity bill — look for the “S” number specifically, which identifies your supply point).
- Meter details and serial number — SEG requires a meter capable of recording export in half-hourly or similar granularity; most modern smart meters manage this, but always confirm with the new supplier before you apply.
- System details: installed capacity in kW, panel and inverter make/model, and the date of commissioning.
4. Apply to your new SEG supplier before or as soon as your old contract ends — not weeks after. Processing typically takes a few days to a few weeks depending on the supplier, and there’s no guarantee of backdating if you leave a gap, so treat this with the same urgency as arranging your import switch.
5. Confirm your MCS certificate transfers or is re-verified. If your installer registered the system in your name, this is generally straightforward — the new supplier verifies the existing MCS certificate number rather than requiring a fresh installation check. Problems mostly arise when the certificate was issued to a previous homeowner (see below) or when the installer details on file don’t match the system now in place, e.g. after adding a battery or extra panels.
6. Keep meter readings from the switch date. Whichever supplier ends up handling export, you want your own record of the export reading at the point of transition, in case of a dispute over which supplier owes you for which period.
The MCS paperwork problem nobody warns you about
The MCS certificate issue catches out more people than any other part of this process, for two common reasons.
Bought a house with solar already fitted? The MCS certificate is usually issued in the original homeowner’s name, tied to their details, not the property. To register for SEG in your own name, you’ll typically need the previous owner’s MCS certificate number (ask your conveyancer to request this as part of the property information pack) or, in some cases, arrange for the system to be re-certified. This is worth chasing at point of purchase, not two years later when you try to switch SEG supplier and hit a wall.
System modified since the original install? Added a battery, extra panels, or a hybrid inverter? Some SEG suppliers will ask for updated MCS documentation reflecting the current system, not just the original install. If you’ve had any additional work done, get the installer to issue updated or supplementary MCS paperwork at the time of the work — retrofitting this later usually means arranging a return site visit.
If your original installation used a certified installer, this is one area where a properly documented job pays for itself years later. Installers such as Green Linc Renewables in Lincolnshire and FLD Electrical in Swansea issue MCS certification as standard practice on every domestic install, which is exactly the paperwork trail you want sitting in a folder for this scenario.
What actually happens if you get the sequencing wrong
Two failure modes come up repeatedly:
- Export gap: your old SEG contract ends (or you deliberately end it to switch), you don’t get the new one live in time, and you generate export electricity for nothing for however many weeks the gap runs. Unlike import electricity, there’s no automatic “deemed contract” that kicks in for export the way there is for import supply — if there’s no contract, there’s no payment for that period.
- Import/export mismatch confusion: some households assume switching their import supplier automatically moves their export arrangement too, then are surprised months later to find their SEG payments stopped when the old import contract closed. The two are administratively separate even when they happen to be with the same company.
The fix for both is the same: treat the SEG switch as its own task with its own deadline, run it in parallel with (not as an afterthought to) your import switch, and don’t let your old SEG contract lapse before the new one is confirmed live.
Battery owners: one extra wrinkle
If you’ve added a battery since your original solar install — increasingly common given how battery costs have come down — check whether your SEG supplier’s export rate and metering setup correctly reads net export (accounting for battery charge/discharge cycles) rather than assuming all generation is exported instantly. Not every supplier’s SEG product is equally battery-friendly, and if you’re generating and storing rather than exporting instantly, some tariffs suit that pattern better than others. Worth checking the tariff structure rather than picking on rate alone. If you’re weighing up whether a battery is worth adding in the first place, the payback maths depends heavily on your import tariff structure and how much you currently export for a low rate — the solar battery storage cost breakdown on The Cost of Solar is a useful place to run the numbers before you commit.
A note on installer choice and paperwork quality
None of this SEG re-registration hassle exists if your original install was done properly and documented well in the first place — which is really an argument for choosing installers who treat MCS certification and handover paperwork as core to the job, not an afterthought. Installers like ECO Aim in Livingston, Premier Electrical Renewables and Yeers in Yorkshire all issue MCS certificates and full system documentation as standard, which is exactly what you’ll be digging out of a drawer when you come to switch SEG supplier in a few years’ time. If you’re not sure your existing paperwork is in order, it’s worth asking your original installer for a fresh copy before you need it urgently.
It’s also worth remembering that 0% VAT currently applies to residential solar and battery storage installed in Great Britain until 31 March 2027, after which it’s scheduled to revert to 5% — relevant if you’re weighing up whether to add a battery now, since the metering and export considerations above apply whether you install solar and battery together or add storage later.
For landlords and small commercial sites
If you’re managing solar across a rental property or small commercial unit rather than your own home, the same import/export separation applies, but the paperwork and contract terms often differ from domestic SEG — commercial export arrangements are frequently negotiated directly rather than via a standard SEG tariff. The commercial solar finance and business solar ROI calculator resources are worth a look if you’re trying to model export income against a commercial system, and the landlord EPC and MEES compliance guide is relevant if the property’s rating is also part of your decision-making.
The practical checklist
Before you touch any switch button, have this ready:
| Document | Where to get it | Why it matters |
|---|---|---|
| MCS certificate number | Original installer, or previous owner via conveyancer | Mandatory for any SEG application |
| MPAN (S-number) | Your electricity bill | Identifies your export point |
| Meter serial + type | Meter itself or supplier portal | Confirms export-capable metering |
| System capacity (kW) & commission date | Installer handover pack | Confirms eligible system size and age |
| Current SEG contract end date | Existing SEG supplier portal | Sets your switching deadline |
Do this properly once and future switches become a five-minute admin job rather than a scramble. Get the sequencing wrong and you’re looking at weeks of unpaid export and a slightly awkward call to a call centre trying to explain why your solar panels apparently haven’t been generating anything for the last two months — when of course they have, it just hasn’t been going anywhere near your bank account.
For more on how solar and battery systems perform in UK conditions once they’re up and running, our sister guide on whether solar panels actually work in the UK climate covers the yield side of the equation, while solar panel maintenance in the UK is worth a read if it’s been a few years since anyone checked your system over.