The world's deserts are sufficiently large that, in theory, covering a fraction of their landmass with PV systems could generate many times the current primary global energy supply. Moreover, the energy produced is from solar radiation -- a clean and renewable source -- hence such systems would have the potential to contribute massively to the protection of the global environment. Energy from the Desert is an extensive and high-level international study, representing the accumulated research of the world experts involved in Task VIII of the IEA PVPS Programme. To date, the market focus for photovoltaics has been on small to medium, stand-alone or building-integrated power systems, which have proven, but as yet not realized, the great potential of this technology. This definitive study evaluates the feasibility, potential and global benefits of very large scale photovoltaic power generation (VLS-PV) systems deployed in desert areas and each generating from 10MW to several gigawatts.