MCS Certification, DNO G98 vs G99 Approval & 0% VAT Rules Explained
Essential UK regulatory checklist before signing a solar quote: ENA G98 (3.68kW limit) vs G99 prior approval, Part P electrical sign-off, and bird mesh protection.
Under Energy Networks Association (ENA) Engineering Recommendation G98, single-phase domestic solar inverters rated up to 3.68 kW (16 Amps) can be installed under a "Fit and Inform" basis, where the installer notifies the DNO within 28 days of commissioning.
If you choose a larger 5.0 kW to 8.0 kW hybrid inverter or a 13.5 kWh Tesla Powerwall 3 (11.04 kW inverter), your installer must submit an ENA G99 application to the regional DNO before energizing the system. Most UK DNOs now offer G99 Fast-Track approval within 10 to 15 working days when paired with G100 export limitation.
Always verify that your installer is registered with MCS (Microgeneration Certification Scheme), RECC or HIES consumer code protection, and a Part P Competent Person Scheme (NICEIC or NAPIT). Without an MCS certificate, you cannot claim Smart Export Guarantee payments and solicitors may flag the installation during a future house sale.
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