Get clear answers to the top 20 questions about 800W plug-in solar kits in the UK. Covers safety, costs, and the 2026 law change.

BS 7671 Amendment 4 (2026): Key Updates for Plug-in Solar

Our site accurately reflects the upcoming BS 7671 Amendment 4 electrical regulations. To demonstrate our in-depth industry knowledge, here are the specific chapters most relevant to plug-in solar systems and modern energy storage:

• Chapter 708 – Small Generating Sets This brand-new section directly addresses the safe connection of small-scale generators — such as 800W solar microinverter systems — in parallel with the existing grid supply. It provides the regulatory framework that will enable compliant plug-in solar installations in the UK.

• Chapter 702 – Stationary Secondary Batteries This dedicated chapter introduces strict requirements for the installation of stationary batteries, with a strong emphasis on fire safety, thermal management, protection against electric shock, and proper segregation.

Important Timeline

Amendment 4 to BS 7671:2018 will be published on 15 April 2026. It can be used immediately for new electrical work from that date. The previous version of the regulations will be withdrawn on 15 October 2026, after which compliance with Amendment 4 becomes mandatory for all new installations.

Critical Safety Information

On the same day the government signalled support for easier rollout of plug-in solar, the Institution of Engineering and Technology (IET) issued an important safety reminder. We believe in transparency, so we address this directly to help keep you safe.

The main concern relates to older household wiring and Residual Current Devices (RCDs) in your consumer unit. Solar inverters can produce small amounts of DC leakage current, which may impair the operation of older Type AC RCDs, preventing them from tripping correctly during a fault.

Recommendation:

Before connecting any plug-in solar system, we strongly advise having a competent, registered electrician inspect your consumer unit. They should confirm it is fitted with modern Type A or Type B RCDs (or equivalent protection) suitable for use with inverters. This simple check significantly reduces risk and ensures your installation remains safe and compliant.

Realistic Yield and Performance Expectations

Trustworthy advice means setting realistic expectations. In typical UK conditions, a well-positioned 800W plug-in solar system (facing directly south with no shading) will usually generate between 300 and 500 kWh of electricity per year, depending on your exact location and local weather patterns.

It’s important to understand that even minor shading from a tree, chimney, or neighbouring building can significantly reduce output. Microinverter systems are sensitive to this because shading on even one panel affects the performance of the entire string due to how the electrical flow is managed.

If you're considering a DIY plug-in solar setup, factor in your roof orientation, potential shading, and local sunlight hours to get a more accurate picture of likely savings.