Hybrid perovskites, composed of an organic cation, inside a post transition metal halide framework, have emerged since 2009 as simple, low cost solar cell materials, with power conversion efficiencies that are competitive with silicon. The commercial viability of perovskite solar cells is yet to be proven with stability being the major limiting factor. These hybrid perovskites are highly sensitive to environmental conditions and quickly degrade under the mildest of thermal treatment. We have isolated a series of new hybrid perovskite with unprecedented chemical and thermal stability. We propose to use neutron scattering to measure critical parameters within these new systems to understand their properties better. This will greatly progress our plans for commercialisation into a new generation of solar materials.