Do you have a sunny place to put solar panels? You'll need around five square metres of roof space which faces East to West through South and receives direct sunlight for the main part of the day. The panels don't have to be mounted on a roof however. They can be fixed to a frame on a flat roof or hang from a wall.
Do you have space for a larger, or an extra, hot water cylinder? If a dedicated solar cylinder is not already installed then you will usually need to replace the existing cylinder, or add a dedicated cylinder with a solar heating coil.
Is your current boiler compatible with solar water heating? Most conventional boiler and hot water cylinder systems are compatible with solar water heating. If your boiler is a combination boiler (combi) and you don't currently have a hot water tank, a solar hot water system may not be compatible.
A competent accredited installer will be able to assess your home and help you choose the best setup to meet your needs.