Great British Insulation Scheme (GBIS) Solar Integration Guide

Key Takeaways

• The Great British Insulation Scheme (GBIS), formerly known as ECO+, is administered by Ofgem to deliver rapid insulation upgrades to lower-efficiency British homes.
• Under statutory rules, eligible homes include private domestic premises in Council Tax bands A to D in England, and bands A to E in Scotland and Wales, with EPC ratings of D-G.
• GBIS places an obligation on medium and large energy companies to deliver measures that result in reduced energy usage.
• While GBIS targets single fabric insulation measures, combining insulation with rooftop solar PV maximises efficiency, supported by a statutory zero rate of VAT until 31 March 2027.
• From 1 February 2024, electrical storage batteries and retrofitted smart diverters also qualify for the temporary 0% VAT relief.

Understanding the Great British Insulation Scheme (GBIS)

The Great British Insulation Scheme is a government energy efficiency scheme, formerly known as ECO+, administered by Ofgem. Designed to assist British households in curbing rising utility overheads, it focuses on tackling fuel poverty by delivering targeted improvements to properties with poor thermal performance.

Unlike the comprehensive "whole house" retrofit model established under the wider Energy Company Obligation (ECO4) framework, the Great British Insulation Scheme was formulated to rapidly deliver single insulation measures. The scheme began in April 2023 and closed on 31st March 2026. The statutory mechanism functions by placing a binding obligation on medium and large energy supply licensees to execute approved energy-saving installations across eligible customer homes.

Statutory Eligibility: Council Tax Bands and EPC Thresholds

Statutory eligibility for GBIS is formally codified under The Electricity and Gas (Energy Company Obligation) Order 2023 Statutory Instrument 2023 No. 873. The framework divides eligible applicants into two core categories: the general group and the low-income help to heat group.

Council Tax Valuation Bands

For the general group, qualifying dwellings must be located in designated local council tax bands:

• England: Private domestic premises in Council Tax valuation bands A to D.
• Scotland and Wales: Private domestic premises in Council Tax valuation bands A to E.

Energy Performance Certificate (EPC) Requirements

In addition to the local authority valuation band, the dwelling must have an Energy Performance Certificate (EPC) rating indicating substantial room for thermal improvement:

• The pre-installation EPC rating must be band D, E, F, or G.
• For qualifying households occupied by a member of the statutory help to heat group, eligibility is tied to means-tested support benefits as defined in Schedule 1 to the 2022 Order.

Once an application is initiated, the customer's designated energy supplier arranges a formal technical survey to assess the structural fabric of the property.

Integrating GBIS Fabric Measures with Rooftop Solar PV

A fundamental challenge in domestic microgeneration is preventing self-generated heat and power from escaping through uninsulated roof spaces and uninsulated cavity walls. When domestic solar PV is deployed on an uninsulated dwelling, the homeowner must run heating appliances longer to offset thermal envelope loss.

By taking advantage of GBIS insulation measures—such as loft insulation, pitched roof insulation, or cavity wall insulation—homeowners lower their property's baseline heat loss. Although GBIS does not fund standalone solar PV generation equipment directly, modernising the building envelope creates the optimal foundation for residential solar arrays.

UK 0% VAT Relief on Solar PV, Battery Storage, and Smart Diverters

While GBIS covers building insulation, domestic microgeneration installations in Great Britain benefit from HMRC statutory VAT relief under VAT Notice 708/6 (Energy-saving materials and heating equipment).

Scope of the Zero Rate

Under UK tax legislation, a zero rate applies to the installation of specified energy-saving materials in residential accommodation from 1 May 2023 to 31 March 2027. This zero-rate relief applies both to the installation service and to the supply of materials provided by the installer.

Sourced Microgeneration Equipment

The VAT relief covers critical solar and energy management hardware:

• Solar Photovoltaic Systems: Photovoltaic (PV) panels supplied with necessary DC cabling, balance-of-system control panels, and AC/DC inverters.
• Electrical Battery Storage: From 1 February 2024, electrical storage batteries installed in residential accommodation or buildings used solely for relevant charitable purposes qualify for the zero rate of VAT. This includes both retrofitted battery systems and standalone grid-tied batteries.
• Smart Energy Diverters: From 1 February 2024, the retrofitting of a smart diverter to microgeneration systems also qualifies for the zero rate of VAT, enabling excess solar generation to heat domestic water cylinders automatically.

Practical Steps to Access Support and Implement Upgrades

Homeowners seeking to coordinate GBIS insulation measures with solar installations should follow a clear delivery pathway:

1. Supplier Assessment: The energy supplier arranges a whole-house survey to evaluate existing cavity walls, loft depth, and roof rafters.
2. Fabric Measure Completion: Installers certified under relevant British standards fit the insulation measure, ensuring that ventilation paths remain unobstructed.
3. Solar Array Sizing: A certified MCS microgeneration contractor designs the solar PV string and inverter setup to match the improved energy demand profile.
4. Zero VAT Billing: The solar installer applies the statutory 0% VAT rate across panels, hybrid inverter switchgear, and battery units directly on the invoice.