  Dark energy models and modified gravity theories have been actively studied
and the behaviors in the solar system have been also carefully investigated in
a part of the models. However, the isotropic solutions of the field equations
in the simple models of dark energy, e.g. quintessence model without matter
coupling, have not been well investigated. One of the reason would be the
nonlinearity of the field equations. In this paper, a method to evaluate the
solution of the field equations is constructed, and it is shown that there is a
model that can easily pass the solar system tests, whereas, there is also a
model that is constrained from the solar system tests.
