The present disclosure provides methodologies for manufacturing photovoltaic devices. In particular, the disclosure relates to the use of hydrogen during manufacturing of photovoltaic devices for passivating defects in the silicon and addressing light-induced degradation. The methodologies in the present disclosures take advantage of generation and manipulation of hydrogen in the neutral or charged state to optimise defect passivation. Some of the methodologies disclose use thermal treatments, illumination with sub-bandgap photons, electric fields or defects in the silicon to control the state of charge or hydrogen, move hydrogen to different locations in the device or retain hydrogen at specific locations.