We suggest a new adiabatic approach for the description of three charged particles in the continuum. This approach is based on the Coulomb-Fourier transformation of a three-body Hamiltonian, which allows us to develop a scheme, alternative to the Born-Oppenheimer one. The approach appears as an expansion of the kernels of corresponding integral transformations in terms of small mass-ratio parameter. To be specific, the results are presented for the system ppe in the continuum. The wavefunction of such a system is compared with the one which is used for the estimation of the rate for triple reaction p + p + e → d + v, which takes place as a step of the pp-cycle in the centre of the Sun. The problem of microscopic screening for this particular reaction is discussed.