Many businesses in the UK generate their own energy via PV solar panels in order to supplement the energy that they use from the grid. Any excess can be fed back into the national grid. Feed in Tariffs are the mechanism by which energy suppliers pay their customers for this energy.
Although British Gas do offer Feed in Tariffs, these are no longer available for new customers. You can, however, apply for the Smart Export Guarantee. This is available to both business and domestic customers, and works in the same way as a Feed in Tariff, albeit with slightly different rates.