Many new build homes now incorporate low or zero carbon (LZC) technologies as part of the wider drive to reduce energy use and meet modern building regulations. Chapter 8.5 of the NHBC Standards 2026 sets out the requirements for LZC systems that provide hot water, with the current section focusing specifically on solar thermal hot water systems. In simple terms, solar thermal panels capture energy from the sun and use it to heat water in a cylinder, helping to supply your domestic hot water with a reduced reliance on gas or electricity.
If your new home includes a solar thermal system, the way it has been designed, installed and handed over should follow the standards summarised below. The aim of this guide is to explain what each sub-chapter covers in plain English so that you can understand what to expect from your developer.
8.5.1 Solar Thermal Hot Water Systems
This is the principal section of the chapter and covers the design, installation and handover of solar thermal panels along with their associated pipework, controls and storage. A typical system comprises a solar collector on the roof, a pump, an expansion vessel and relief valve, a discharge storage vessel and a hot water store that is also connected to the boiler.
8.5.1.1 Compliance
Solar thermal systems must comply with the relevant British and European standards, carry appropriate product certification, and be installed by competent operatives. NHBC will generally accept products certified through the Microgeneration Certification Scheme (MCS), and installers should be MCS Certified or hold an equivalent qualification accepted by NHBC. As a homeowner, you can ask your developer to confirm the system meets these requirements, and you should expect to see supporting evidence within your handover pack.
8.5.1.2 Provision of Information
Designers and specifiers must produce clear, detailed drawings and specifications and share them with everyone involved in the installation, including site supervisors, subcontractors and suppliers. The information should cover fixing schedules, commissioning, manufacturer specifications, pipe runs, and the location of cisterns and cylinders. Although this happens behind the scenes, the discipline involved helps prevent the kind of errors that later show up as leaks, poor performance or overheating in the home.
8.5.1.3 System Design
Systems must be designed to perform satisfactorily, taking account of location, the chosen system, compatibility with other components and the building, and overall performance. Collectors should be positioned in line with manufacturer recommendations, and homes within 500 metres of the coast need components suitable for the harsher, salt-laden environment. The system should generally come from a single manufacturer as a complete package, and it should be sized correctly to avoid stagnation, which can damage the collectors over time.
8.5.1.4 Safe Discharge
Solar thermal systems can reach very high temperatures, so any discharge from the system must terminate safely. The pipework and the storage vessel that receives the discharge should both be capable of withstanding these temperatures, ensuring there is no risk of scalding, leaks or damage to the surrounding fabric of the home.
8.5.1.5 Building Integration
The collectors and supporting framework must be securely fixed to the structure and must not compromise the weather resistance of the building. The structural design should account for the self-weight of the panels, imposed loads, wind loads and any dynamic loading. All junctions between the panels and the roof should be properly weatherproofed using appropriate flashings and a sealed membrane. The standards are explicit that weatherproofing relying solely on sealant is not acceptable, an important point given how much rainfall a UK roof has to cope with.
8.5.1.6 Fixing
Fixings, brackets and mounting frames must be made from suitably durable materials such as phosphor bronze, silicon bronze, stainless steel, mild steel with appropriate corrosion-resistant coatings, or aluminium alloy to recognised standards. For homes in coastal locations, grade 316 stainless steel is recommended due to its higher resistance to corrosion. Dissimilar metals must be isolated from one another to prevent bimetallic corrosion, and aluminium must not come into direct contact with cementitious materials such as mortar.
8.5.1.7 Access
The system must be installed in a way that allows it to be reached for maintenance, servicing and eventual removal or replacement. Where parts of the system, such as pumps, controls or pipework, are located in a loft or roof void, suitable access provisions are required. This is important throughout the life of the system, as periodic servicing helps maintain efficiency and longevity.
8.5.1.8 Electrical Installation Requirements
Any electrical work associated with the solar thermal system must comply with BS 7671, the Wiring Regulations. The installation should also be capable of being safely isolated from other electrical sources when required for maintenance or testing. This protects both anyone carrying out future work and you as the occupant.
8.5.1.9 Handling and Storage
Components should be handled, stored and protected on site in line with the manufacturer’s recommendations, and ideally delivered in sequence so that they are not left exposed for long periods. This reduces the risk of damage, distortion or weathering before the system is even installed, any of which could affect long-term performance.
8.5.1.10 Handover Requirements
When your home is handed over, you should receive a comprehensive information pack covering the solar thermal system. This should include user instructions, contact details for the manufacturer and installer, a list of key components, a completed manufacturer’s certificate (typically MCS or an acceptable alternative), maintenance and servicing requirements, and any warranties or guarantees. You should also be given guidance on how to protect the collectors if they have not yet been filled with solar fluid, as the panels can otherwise be damaged.
8.5.1.11 Sequence of Work
Finally, the standards require that the system is installed in a logical and timely sequence, in line with the manufacturer’s recommendations. In practice, this means components should not be fitted out of order or left exposed unnecessarily, since either could compromise performance or potentially affect warranties.
How a Snagging Inspection Fits In
A professional snagging inspection from New Build Inspections can identify many of the visible issues associated with a solar thermal hot water system. These include obvious problems with flashings or weatherproofing around the panels, visible signs of poor or incomplete installation, missing or incomplete handover documentation, and any accessible defects to pipework, controls or the storage vessel. We can also flag where the homeowner pack appears to be lacking the certificates and user information that NHBC expects you to have.
It is important to be clear, however, that a snagging inspection is not a full structural survey or a specialist mechanical and electrical test. We do not dismantle the system, verify structural calculations for the fixings, or carry out detailed electrical testing or pressure testing of the solar circuit. Where a visible defect suggests a deeper issue, such as signs of leakage at a roof junction or evidence of poor commissioning, we will highlight it in your report and recommend that the developer arrange the appropriate specialist checks.
If you are about to take handover of a new build home that includes a solar thermal system, a snagging inspection is a sensible step towards confirming that the visible elements have been installed to a reasonable standard and that you have received the documentation NHBC expects you to be given.
