The study evaluates the performance of van der Waals density functionals (vdW-DF) in describing solid-state properties, focusing on lattice constants, bulk moduli, and atomization energies. The original vdW-DF method, proposed by Dion et al., is compared with several modified versions, including revPBE-vdW, rPW86-vdW2, optPBE-vdW, and optB88-vdW. The results show that the original vdW-DF overestimates lattice constants and binding distances, similar to its overestimation in gas-phase dimers. However, the modified functionals, particularly optB88-vdW and optB86b-vdW, exhibit average errors comparable to or better than those of the PBE functional. These functionals also show improved atomization energies for solids, especially for alkali metals and alkali halides, where non-local correlations are crucial. The study highlights the importance of non-local correlations in accurately describing solid-state materials, particularly those with large polarizability, such as alkali metals and halides. The optimized functionals are shown to provide more accurate lattice constants and atomization energies, with optB86b-vdW and optB88-vdW performing the best. The findings suggest that further development of vdW-DF methods is needed to reduce the range of errors in lattice constants and improve the accuracy of atomization energies.The study evaluates the performance of van der Waals density functionals (vdW-DF) in describing solid-state properties, focusing on lattice constants, bulk moduli, and atomization energies. The original vdW-DF method, proposed by Dion et al., is compared with several modified versions, including revPBE-vdW, rPW86-vdW2, optPBE-vdW, and optB88-vdW. The results show that the original vdW-DF overestimates lattice constants and binding distances, similar to its overestimation in gas-phase dimers. However, the modified functionals, particularly optB88-vdW and optB86b-vdW, exhibit average errors comparable to or better than those of the PBE functional. These functionals also show improved atomization energies for solids, especially for alkali metals and alkali halides, where non-local correlations are crucial. The study highlights the importance of non-local correlations in accurately describing solid-state materials, particularly those with large polarizability, such as alkali metals and halides. The optimized functionals are shown to provide more accurate lattice constants and atomization energies, with optB86b-vdW and optB88-vdW performing the best. The findings suggest that further development of vdW-DF methods is needed to reduce the range of errors in lattice constants and improve the accuracy of atomization energies.