  Triple junction (InGaP/GaAs/Ge) and single junction (SJ) solar cells were
irradiated with electrons, protons and neutrons. The degradation of remaining
factors was analyzed as function of the induced Displacement Damage Dose (DDD)
calculated by means of the SR-NIEL (Screened Relativistic Non Ionizing\ Energy
Loss) approach. In particular, the aim of this work is to analyze the variation
of the solar cells remaining factors due to neutron irradiation with respect to
those previously obtained with electrons and protons. The current analysis
confirms that the degradation of the $P_{max}$ electrical parameter is related
by means of the usual semi-empirical expression to the displacement dose,
independently of type of the incoming particle. $I_{sc}$ and $V_{oc}$
parameters were also measured as a function of the displacement damage dose.
Furthermore, a DLTS analysis was carried out on diodes - with the same
epitaxial structure as the middle sub-cell - irradiated with neutrons.
