Solar export tariffs and batteries
How to calculate solar export income, compare SEG export tariffs and understand battery export rules.
Key takeaways
- SEG suppliers set their own tariff rates, types and contract terms.
- The export supplier can be different from your import supplier.
- A simple solar export calculation is exported kWh multiplied by your export rate.
- Battery export rules vary, especially when stored energy may come from the grid.
Flat export rates
A flat export tariff pays the same rate for exported electricity regardless of time. It's easy to model: exported kWh multiplied by p/kWh.
This is the simplest option for a calculator and for household planning. The downside is that it may miss the extra value some suppliers offer for exporting at particular times.
How to calculate solar export income
The simple solar export calculator formula is exported kWh x export rate. If your system exports 2,000kWh a year and your export rate is 15p/kWh, export income is about £300 a year.
That export income sits alongside bill savings from self-used solar. Keep the two separate because self-used electricity is valued at your import tariff, while exported electricity is valued at your export tariff.
Time-of-use export
Some tariffs pay different rates at different times. With a battery, that can make exporting later in the day more valuable than exporting at midday.
This can be powerful, but it also depends on supplier terms, battery controls, import tariff, battery losses and whether the export is from solar or from energy previously imported from the grid.
SEG rules and supplier choice
Ofgem's guidance says SEG licensees decide the rate, type and length of their export tariff, but the rate must be greater than zero at all times. You can apply to a SEG licensee that isn't your import electricity supplier.
That flexibility is useful. It also means the market changes. Don't assume an old tariff comparison is still current when you're ready to apply.
What to ask if you have a battery
Battery wording is where tariff pages can get slippery. Ask whether the supplier pays for all measured export, only solar-generated export, or excludes energy that may have been imported and stored.
If the tariff requires the supplier to control your battery, make sure you're comfortable with that. Optimisation can improve returns, but it changes how the battery behaves.
- Can I keep my current import supplier?
- Do you pay for battery export?
- Do you require MCS or equivalent paperwork?
- How often are export readings and payments handled?
Sources checked
- Ofgem SEG guidance for generatorsOfficial SEG eligibility, certification, metering and payment guidance.
- Ofgem SEG supplier listCurrent SEG licensee list and annual supplier status.
- Energy Saving Trust solar panel guideConsumer guidance on costs, payback, savings, grants and maintenance.