Looks like the VAT increase was scrapped in 2016, however it’s been added from last month. Looks like the Tories are blaming the EU for the raise. However, another site says that the increase due to be applied in October, will not go ahead as the panels count as energy efficiency and all energy efficiency measures are set at 5%.
I just checked a German website and they are having the same issues, that site is saying that the increase has been lobbied by the power companies who are losing profit to home owners with solar panels. Unlike the UK where solar installations are mainly fitted to South facing roofs, German house owners are getting them fitted to East and west roofs. That way the householder gets the benefit of free electric in the morning and evening when the houses are occupied and people are using electricity but the power companies are losing out as they don’t get as much fed back into the grid, so they want the government to ” fine” home owners for not giving them free electricity.