Abstract: An external building element has the size and shape of a standard roofing or building product but incorporates a monolithically interconnected solar cell array within which a plurality of interconnected thin film solar cells are integrated on an electrically insulating substrate. The cells are positioned in one or more rows with the cells being electrically connected together in series and being connected by electrically conducting tracks to two output tracks. The output tracks of each element may be automatically interconnected to the output tracks of the adjacent elements when the elements are placed adjacent one another along a horizontal support rail so as to electrically connect the solar cell assemblies of the elements in parallel. Further similar elements may be positioned in overlapping rows. Such an element incorporating a solar cell array is substantially uniform in colour and may be designed to provide a very close visual match to standard building products, such as natural and synthetic slates.