Export tariffs

An export tariff is what your business is paid for electricity it sends to the grid from solar, a battery, or both. It is the neglected half of the tariff question. Businesses that negotiate their import price carefully will often accept whatever export arrangement is put in front of them, even though the same market logic applies: the power has a time-varying value, and the arrangement either reflects that value or someone else keeps the difference.

The structural options are straightforward. Smaller installations can use Smart Export Guarantee tariffs, under which suppliers must offer some payment for metered export. Larger commercial systems typically contract through a power purchase agreement with a supplier or offtaker. In both cases the rate can be fixed or market-linked, and in both cases the export must be settled on half-hourly metering.

Why export value is a shape question

Exported solar power is concentrated in the daylight hours, and increasingly those are the hours when abundant renewable generation pushes wholesale prices down. A battery changes the shape: it can hold power back from low-value periods and export into higher-value ones, including the evening peak. The value of your export therefore depends less on the headline rate than on when your electrons leave the site, which is a modelling question, not a brochure question.

A battery turns export from a fixed characteristic of the array into a decision made site by site, half hour by half hour. Without storage, solar exports whatever it generates beyond immediate demand, at whatever time that happens to be, which on a sunny day is usually the low-value middle of the day. With storage, the same surplus power can be held back and either used later on site or exported during a window when the price is actually worth having, such as the evening peak on a market-linked tariff. The economics improve twice over: self-consumption rises because stored generation displaces import later in the day, and whatever is still exported earns more because it leaves at a better time.

The same site that discovered its real export was under 1%, not the 17% it had assumed, had a hard ceiling on top of that: a 95 kW export cap, enforced by the DNO connection agreement and a physical export-limitation scheme at the meter. With export capped and self-consumption already close to total, chasing headline export revenue was never going to be where the value sat. It came from holding generation behind the meter and shifting load to use it, not from selling a surplus the connection would not let leave the site anyway. Where a quote leans on export revenue to make its payback work, that is usually telling you something about how the system was sized, not about how good the export rate is.

Self-consumption first

Every exported unit is a unit that failed to displace an imported one, and imports cost more than exports pay. The hierarchy is fixed: consume on site first, shift with storage second, export last. This is why export income should never rescue a business case. A proposal that leans on export revenue to make its numbers work is usually describing an oversized system.

There is a pattern worth naming in proposals that lean on export income to make the numbers work: it is usually a sign the system has been sized to the roof rather than to the load. A correctly sized system, built from the site’s own half-hourly consumption, self-consumes the large majority of what it generates, and export becomes a modest top-up rather than a line the payback depends on. When a quote shows export revenue carrying a meaningful share of the annual saving, the more likely explanation is not an exceptionally good export rate, it is an exceptionally large system relative to demand, generating more than the site can use. The tell is easy to check: ask what proportion of the projected saving comes from export rather than self-consumption, and ask what consumption data the sizing was built on. A quote that cannot answer either question cleanly was probably sized on the roof, not the meter.

Reading an export offer

Ask three things of any export arrangement: what is the rate and how does it relate to market prices at your export times; what is the term and what happens at the end of it; and how does it interact with your import contract, since import and export sit best when structured together. An import tariff and an export tariff designed as one system will beat two arrangements negotiated separately.

To have your import and export position reviewed together, request a benchmark at /benchmark or book a review at /book.