The electrical characteristics of InGaP n(+)/p/p(+), solar cells are unstable under illumination below typically 200 K. We show that this effect is metastable. We demonstrate using capacitance and current-voltage measurements coupled with deep level transient spectroscopy that this metastability is a result of the presence of DX centers, associated with the donor impurities in the emitter. (C) 2002 Published by Elsevier Science B.V.