The realization of a net-zero energy built environment is challenging, especially in dense city centers with highrise buildings. While in suburban residential areas, roof space in combination with efficient solar photovoltaics (PV) can lead to energy self-sufficiency, for high-rise buildings this is only potentially possible if all façades are also harvesting solar energy. For aesthetic and occupational health reasons, PV façades should be (partly) transparent and color-neutral. Solar energy harvesting windows based on luminescent solar concentrators are one class of transparent PV that combines transparent waveguides concentrating light on their sides where solar cells are mounted. A compromise between color-neutral transparency and harvesting efficiency must be found, leading to average visible transparency values of >70%, color rendering index >80, and efficiencies of 2-3%. A range of luminescent species embedded in the waveguide has been investigated, from organic dyes to nanoparticles based on chalcogenides and perovskites, while combinations of those are investigated as tandem structures. This contribution will review recent experimental and simulation results, and will derive promising strategies to approach a theoretical limit of 20% color-neutral transparent efficient luminescent solar concentrators, which is based on full utilization of the UV/blue and the red/IR part of the solar spectrum, with limited utilization of the visible part.