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Hydrogen embrittlement of ferritic steels is governed by hydrogen partitioning between bulk interstitial sites and microstructural traps such as grain boundaries, vacancies, and solute-associated defects. We perform a large-scale density functional theory study of hydrogen solution energies in bcc Fe across multiple grain-boundary characters, vacancy defects, and substitutional solutes (Cr, Cu, Ti). We evaluate geometric and electronic descriptors and find that the relaxed atomic environment prior to H insertion is sufficient to predict the solution energy. Geometric descriptors control the energy landscape, while electronic descriptors provide limited additional predictive power for the grain-boundary environments and dilute alloy chemistries studied here. The same descriptors also capture the zero-point-energy contribution. A Gaussian process regression surrogate trained on these descriptors accurately reproduces DFT energetics; notably, a minimal two-descriptor model retains much of the predictive power, enabling descriptor-based screening of hydrogen solution energies in complex microstructures without electronic-structure calculations.