Find Zero function

[kong17]

Dear

I try to build a model about electricity market. For the investment in the new power plant, I use the IRR calculated by the NPV to evaluate. Therefore, in each year, I need to calculate the IRR from the current annual income and points. So I used FIND ZERO function in vensim.
The problem now is that when the annual income is very low, there will be distortions through FIND ZERO, even when profits increase, this situation will continue.
Therefore, I simply expressed the model, and I was wondering how can this situation be avoided.
Thank you very much!

Best wishes

simple.mdl

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[tomfid]

In 2019 and 2020, when profits crash, I think it's numerically impossible to zero the NPV. At that point, IRR gets stuck and what must be a local minimum, because future values don't move off of that point. If you change the "method" to 1, the computation at least recovers after the negative-profit episode.