The biggest challenge is not finding money but finding viable livelihood options for the poor. I suggest you study Prof. Yunus work. First work with the poor and let them come up with local opportunities for generating income. Take a few viable cases and fund them. Once these ventures are viable, you have a proven business plan for the investors. Why investors? You may even go through the regular banking system. Your margin will be what you charge extra above the lending rates. VC funding will put extra pressure on you to charge very high rates and it can be regulated by the govt, as it has happened in India. Such high rates also defeat the core purpose of your business. All the best.