Energy is a vital need of humanity and a primary indicator a of nations’ growth. However, most energy sources we use have low efficiency, rely on non-renewable resources and cause severe damage to the environment. The cleanest resource, and the one which offers virtually unlimited energy is the sun. However, according to the Center for Climate and Energy Solutions, current solar photovoltaics (PV) produce little more than 2% of the world’s electricity. This low output is primarily resulting from two factors: current commercial solar PV cells have approximately 15-20% efficiency, and the price of a 1m2 is around €400. GreEnergy aims to develop a wideband optical antenna array with very high efficiency. The GreEnergy device will integrate the energy-harvesting component in a self-powering nano-system. A prototype of the integrated components will be developed incorporating nano-optical antennas with nano-rectifiers (rectennas) and a micro-energy storage component. Simulations will provide full system level circuitry, act as a benchmark of the proof of concept design and culminate in road mapping for future full-scale development and commercialization. Within GreEnergy, the targeted efficiency of the overall system is 20-40%, while the theoretical efficiency is over 90%, at an estimated system cost below €100 per 1m2. Such a technology would fundamentally change solar energy harvesting and have dramatic effects on consumers, society, economic growth and the environment. Further, demonstration of the system provides a proof-of-concept backbone for numerous future micro/nano-systems such as IoT and nano-sensor applications.