Roof for stable being replaced and fitted with solar panels - architect or structural surveyor needed?

It depends from a planning perspective what are you live in, generally replacing a roof like for like doesn't require planning approval, you possibly may need approval if you live in a conservation area, the barn is listed etc. You may need building regs approval for the structure of the roof depending on the size and additional weight of the solar panels. If you can provide me a picture of the barn I'll be able to give a better opinion. Regards Tony

As far as planning permission is concerned, a quick call to your Local Authority will let you know. As far as building control and building regulations for the structural change, agricultural buildings are exempt from Building Regulations Part A (structures), in other words as far as the building regulations are concerned you don't need to make a building control application. Thats not to say you shouldn't employ the services of a structural engineer to assess the impact of addition loading on the roof for your own piece of mind - but you are obliged too as you don't require a building regulations application.