The Energy Security Strategy document is available, although you can’t find it by googling as that takes you to the press release which doesn’t have a hyperlink.
And when you do find it, it’s not downloadable. Looks like it’s all been done in a rush.
The link is here: https://www.gov.uk/government/publications/british-energy-security-strategy
The extract around solar is as follows:
“For ground-mounted solar, we will consult on amending planning rules to strengthen policy in favour of development on non-protected land, while ensuring communities continue to have a say and environmental protections remain in place.
We will continue supporting the effective use of land by encouraging large scale projects to locate on previously developed, or lower value land, where possible, and ensure projects are designed to avoid, mitigate, and where necessary, compensate for the impacts of using greenfield sites.
We will also support solar that is co-located with other functions (for example, agriculture, onshore wind generation, or storage) to maximise the efficiency of land use. We have also included solar in the latest Contracts for Difference auction round and will include it in future rounds.”