Most of the times, most of the searches are returning the IRR calculation just based on a single initial investment.
Imagine you have a plan that asks investors to supply money not only once, and you
dividend the payments into 2 or more sections within the years.
I have looked at the MIRR concept as well, I think it is telling about re-investing from your cash-flows, if I be right, this is a bit different from the scenario which I defined here, but not totally sure maybe it can work.
I pasted a screenshot of my Excel worksheet which I made, please let me know if it's correct or I need to make some refinements.
** Loss means the timely payments.
** To clarify what I did let me explain the year 1, the project is gaining 500, in the same year the investor should pay another 1300. so the CF and PV of the year as calculated are "-800"