VAT on solar installs as a subcontractor

We are a sub-contractor providing solar panel installations to main contractors and the properties are domestic. Can you let me know the VAT treatment for domestic new build properties and existing domestic premises. I am assuming it's 20% VAT (reverse charge) for commercial type properties. Are there are scenarios where it will be zero-rated when we are billing a contractor? And if VAT is applicable, is it always reverse charge if the contractor is in the Construction Industry. Thanks..

Hi,
If you are installing solar panel installations in to new residential premises then the supply and installation can be zero rated if the criteria is met below:
Zero rating the construction of new buildings
The VAT meaning of ‘building materials
If you are supplying energy saving materials in to commercial premises then these will always be charged at the VAT rate of 20%
If you are supplying in to existing residential premises then this would be charged at the VAT rate of 0% if the conditions are met below:
https://www.gov.uk/guidance/vat-on-energy-saving-materials-and-heating-equipment-notice-7086#installations-of-energy-saving-materials
If VAT is applicable and you are working as a sub contractor to a contractor then this would normally be subject to the reverse charge.
Please see the flow diagram below:
Flowcharts
Thank you.

Just to be clear then, as a sub-contractor being hired by a main contractor firm (not a private individual in their home) if we are delivering energy saving materials (specifically solar panels) to an existing residential property is VAT 20% or zero rated. I understand that it will be reverse charge as a sub-contractor but unclear on the rate of installing to an existing property if we are hired by the contractor not the homeowner.

Hi. It wouldn't make a difference if you are invoicing the contractor or the owner of the property. If the conditions are met for the relief for energy saving materials then the supply would be charged at the zero rate of VAT