The feed-in tariff is part of the government incentives scheme where you get paid for producing your electricity. This energy could be derived from any renewable source like solar panels, wind turbines, hydroelectricity, anaerobic digestion etc.
The feed-in tariff is divided into two parts:
Generation tariff - You get an incentive for every kWh of power produced using your solar tiles.
Export tariff - You get paid if you produce extra energy and send it back to National Grid energy suppliers.
To join the tariff policy, you need to ensure that your solar tiles or panels are purchased from credited suppliers registered under Microgeneration Certification Scheme (MCS). You can register for the Feed-in tariff and Renewable Heat Incentive with the MCS certificate.
UK government will pay you for the next 20 years, and the incentive is not considered a part of your personal tax allowance.