The present work is focused on the numerical study of a solar-powered Stirling engine, with the particularity that the solar radiation is injected through a transparent top cover. Thus, the working fluid absorbs the heat across a porous layer of a steel woven wire screen placed alongside the inner side of the transparent wall. The engine output net power and efficiency are studied as a function of the porosity, engine speed, temperature of the expansion chamber, and wire diameter of the screen. It is found that the engine efficiency remains practically constant for porosity values over 0.7, but there is a relevant increase of the engine output net power compared to the same working conditions without the absorbing layer. For a given porosity value, the most significant increase of net power due to introducing the porous layer was reached when doubling the engine speed resulting in an increment close to 40%.