I have come back just very recently from the Philippines, after spending several months there as a volunteer, working for a local for-profit social enterprise called Hybrid Social Solutions (HSSi). The organization has sets itself the goal to bring solar systems (for lighting, ventilation and other appliances) to the rural population that does not have access to electricity (around 20 million).
HSSi is always on the lookout for capable engineers like all of you, which are still studying or just finished and would like to volunteer in the Philippines. I attached a brochure with further information and contacts. I can make an introduction via email to the founder and CEO (Jim Ayala) as well.
Please feel free to ask any further questions here or via private message.