Solar panels need to be installed on a roof or wall that is 90 degrees from south, in order to get the most out of the product. You also need to make sure that trees or other buildings will not overshadow the PV cells as they’ll be less effective in the shade.
You also need to ensure that your roof tiles are strong enough to support the project. Solar panels are not light, and tiles must be able to take their weight, especially if built on existing tiling.
Planning permission is generally not an issue with solar panelling as it’s not needed, providing the equipment is below a certain size. However, it’s always best to double check with a local planning officer, especially if the building if listed or in a conservation area.