The effects of the solvent quality on the adsorption of weakly charged polyelectrolytes at an oppositely charged surface are investigated using the self-consistent mean field theory. The analytical solutions of the self-consistent field equations are obtained in the case of theta, good and poor solvents for the polymer backbone. Using these analytical solutions the thickness of the adsorbed layer is calculated as a function of the surface charge density, salt concentration, and solvent quality. It is shown that for polyelectrolyte adsorption from theta and good solvents the surface charge is always overcompensated by adsorbed chains. For low ionic strengths the surface overcharging is inversely proportional to the Debye screening length. However, in the case of adsorption from a poor solvent the adsorbed polyelectrolytes undercompensate the surface charge.