We exploit changes in air quality seen during the COVID-19 lockdown over China to show how a cleaner atmosphere has notable co-benefits for solar concentrator photovoltaic energy generation. We use satellite observations and analyses of the atmospheric state to simulate surface broadband and spectrally resolved direct normal irradiance (DNI). Over Wuhan, the first city placed under lockdown, we show how the atmospheric changes not only lead to a 19.8% increase in broadband DNI but also induce a significant blue-shift in the DNI spectrum. Feeding these changes into a solar cell simulator results in a 29.7% increase in the power output for a typical triple-junction photovoltaic cell, with around one-third of the increase arising from enhanced cell efficiency due to improved spectral matching. Our estimates imply that these increases in power and cell efficiency would have been realised over many parts of China during the lockdown period. This study thus demonstrates how a cleaner atmosphere may enable more efficient large scale solar energy generation. We conclude by setting our results in the context of future climate change mitigation and air pollution policies.