Zero Rate on Energy Saving Materials - Solar Panel Optimisers Included

Hi HMRC Team I'm trying to ascertain whether the installation of new solar panel optimisers (and associated monitoring equipment) is treated as an 'energy saving material' and would therefore be zero rated. The guidance does not mention solar panel optimisers and associated equipment explicitly but does refer to "cabling (and) control panel(s)" as part of PV systems which are eligible. My current interpretation is that as these are integral to the maximise energy efficiency performance of the system, and necessarily constitute both "cabling" and a "control panel," they would qualify for the zero rate. Please could you confirm. Many thanks

Hi,
The following paragraph of HMRC’s public Notice ‘ Energy Saving Materials & Heating equipment ( Notice 708/6) details the types of materials deemed to qualify to be zero-rated when supplied as a single supply.
2.7 Energy-saving materials covered by the zero rate.
Energy-saving materials, when installed in residential accommodation or, from 1 February 2024, a building intended for use solely for a relevant charitable purpose, qualify for relief when they consist of any:
•    controls for central heating and hot water systems (read section 2.8)
•    draught stripping (read section 2.9)
•    insulation (read section 2.10)
•    solar panels (read section 2.11)
•    wind turbines (read section 2.12)
•    water turbines (read section 2.13)
•    ground source heat pumps (read section 2.14)
•    air source heat pumps (read section 2.15)
•    micro combined heat and power units (read section 2.16)
•    wood-fuelled boilers (read section 2.17)
From 1 February 2024 additional materials include:
•    water source heat pumps (read section 2.18)
•    batteries for storing energy converted from electricity (read section 2.19)
•    smart diverters (read section 2.20)
In addition, from 1 February 2024, the temporary zero rate will apply to supplies of groundworks, or dredging a body of water, in order to install pipework or other equipment necessary for the operation of a ground or water source heat pump installed in (or in the curtilage of) residential accommodation or buildings intended for use solely for a relevant charitable purpose.
You will note solar panels are deemed to be an energy saving material and, section 2.11 of the same notice below states:-
2.11 Solar panels
Solar panels include all systems that are installed in, or on the site of, a building and that are:
•    solar collectors such as evacuated tube or flat plate systems, together with associated pipework and equipment, such as circulation systems, pump, storage cylinder, control panel and heat exchanger
•    photovoltaic (PV) panels with cabling, control panel and AC/DC inverter
So, if the replacement inverters are a composite part of a solar panel and, the solar panel needs them to operate then the replacement of a part specifically designed to allow the continued use and operation of the solar panel would be zero-rated when installed in accordance with the guidance shown in paragraph 2.7 above.
Thank you.