MCS installation standards

MCS installation standards are the technical rules an MCS-certified installer follows for a particular low-carbon technology. They sit inside a wider scheme that also covers the installer business, pre-sale information, consumer protection, product evidence and the registration of completed work.

There is no single document called “the MCS standard” that covers an entire solar, battery or heat-pump project. The applicable set depends on the technologies and the work being carried out.

The MCS document stack

Under the redeveloped MCS:2025 scheme, the main layers are:

1. Installer Operating Requirements. These govern how an installer operates within MCS, including scheme scope, business controls and registration of installations.
2. Customer Commitment. This sets the installer’s obligations to the customer.
3. Pre-sale Information and System Performance Estimate Standards. These govern what must be explained and how expected performance is presented before contract.
4. Technology-specific MCS Installation Standards. These contain the design, installation, commissioning or handover requirements for each technology.
5. Product standards and the Product Directory. These address product certification where the scheme requires it.
6. External law and technical standards. Building regulations, planning rules, BS 7671, G98/G99 and other requirements continue to apply independently.

These layers have different scopes. Compliance with a technology standard does not establish that the required pre-sale information, correct contracting entity, DNO process or building-control process has also been dealt with.

Principal standards for home energy work

The following table shows the main entries relevant to Energy Stack. It is a current snapshot, not a substitute for the MCS Standards and Tools Library.

Technology or subject	Principal MCS document	Current edition as at 22 July 2026
Solar PV design and installation	MIS 3002	MIS 3002:2025 Issue 2.0, dated 18 March 2026
Battery storage	MIS 3012	MIS 3012:2025 Issue 1.0
Heat-pump design	MIS 3005-D	MIS 3005-D:2025 Issue 1.0
Heat-pump installation	MIS 3005-I	MIS 3005-I:2025 Issue 1.0
Solar mounting products	MCS 012	Issue 3.0
Air source heat-pump sound assessment	MCS 020 a)	Issue 1.0

The edition number should be recorded. For example, MIS 3002 Issue 2.0 replaced the Issue 1.0 edition named in older material during 2026. Writing only “MIS 3002” makes it impossible to tell which requirements were applied.

What the technology standards do

Solar PV

MIS 3002 covers the supply, design, installation, setting to work and commissioning of qualifying solar PV systems. It links the array, mounting, electrical design, expected performance and handover into one certified installation.

MCS 012 is a product standard for solar mounting kits and components. It does not replace the installer’s obligation to assess the actual roof, loading, fixings and weathering. A certified mounting product can still be badly specified or installed.

Battery storage

MIS 3012 covers qualifying electrical energy storage installations and allocates responsibility according to the way the battery and power-conversion components are packaged or selected. It works alongside BS 7671, PAS 63100, DNO requirements and manufacturer instructions.

MCS:2025 expressly excepts battery-storage products from its normal rule requiring an actively certified product in the MCS Product Directory. That exception does not remove the need for suitable product evidence or make every battery acceptable.

Heat pumps

MCS separates heat-pump design from installation. MIS 3005-D covers the design work, including the building heat-load and system design. MIS 3005-I covers installation, commissioning and the evidence that the design has been delivered.

MCS 020 a) is a separate sound-assessment standard for air source heat pumps. Permitted-development rules may refer to the MCS method, while other planning conditions and MIS 3005 remain separate requirements.

EV charging

EV chargepoint installation is not an MCS technology in its own right. An EV charger may be part of a wider home-energy project, but its installation uses the EV charging, electrical, product and DNO rules that apply to it. It should not be described as MCS-certified merely because the same contractor is also carrying out MCS solar or battery work.

Which version applies

MCS:2025 says the latest edition of each relevant scheme document, including amendments, applies as published in the MCS library. In practice, a project can span a standards change, and MCS may publish implementation or transition instructions with the revised document.

The installer should therefore record:

• the scheme version under which it is operating
• the edition of each installation and pre-sale standard used
• any published transition provision relied on
• the dates of design, contract, commissioning and certificate registration

That evidence is more useful than a generic statement that the work was “to current MCS”.

What MCS certification does and does not establish

An MCS installation certificate is the certified installer’s statement that the completed installation met the applicable scheme requirements. It provides a traceable scheme record, but it does not guarantee that no fault exists and it does not replace the underlying design and test results.

For example, a solar and battery handover may also need:

• the array design and performance estimate
• structural and mounting evidence
• electrical design, inspection and test certification
• inverter and battery declarations and manuals
• G98, G99 or G100 evidence
• commissioning settings and a system schematic
• PAS 63100 siting and fire-safety evidence
• planning and Building Regulations records where applicable

For a heat pump, the evidence should connect the room-by-room heat loss, emitter and flow-temperature design, selected unit, hydraulic arrangement, controls, commissioning results and performance estimate.

Evidence across the installation

Before installation, the scheme record identifies the exact legal business, its MCS technology scope, the survey and design assumptions, the applicable MCS document editions, external approvals and any subcontracted design or installation responsibility.

At handover, the installed models and ratings connect to the design, MCS installation certificate, design and commissioning records, and the separate electrical, DNO, planning and building-control evidence. Guarantees, financial-protection records and any approved departures or substitutions remain distinct documents.

The current MCS Standards and Tools Library governs the applicable document editions and published transition provisions.

Related entries

• MCS
• MIS 3002 solar PV standard
• MIS 3012 battery storage standard
• MIS 3005 heat pump standard
• MCS 012 solar mounting standard
• MCS 020 heat pump noise calculation
• BS 7671 IET Wiring Regulations
• Building Regulations Parts L and P