Overview
- Roughly 1.6 million UK households now have rooftop solar after a record 2025, with many earning £300 or more a year through the Smart Export Guarantee.
- Analysis suggests about 605,966 solar owners are likely required to file an online Self Assessment for income in the April 2024 to April 2025 tax year.
- HMRC levies an automatic £100 penalty for late returns even if no tax is due, and around 9% of taxpayers typically miss the deadline each year.
- The £1,000 trading allowance covers total supplementary income, so SEG receipts plus freelance or side-business earnings can exceed the threshold.
- Energy experts urge solar households to check supplier statements now to confirm export payments and file promptly if they need to.