Explaining Module C in the MBV spreadsheet
First, Module B is designed just so that you can see the breakdown of your monthly burn rate (i.e. operational fixed costs).
Module A additionally asks you to input your product price, and your variable costs. Then, in the "Baseline 5" row of Module A, your breakeven volume pops out.
Now, what's Module C for?
So, the idea, basically, is to let you play with the numbers. With Module A, you can only play with price, variable costs, and burn rate, and then the spreadsheet takes those and spits out a B/E volume.
But what if you want to see what happens to your pricing, burn rate, and unit costs if your ACTUAL volume is lower than the breakeven volume? So for example, you expect that ACTUAL volume is only 26 instead of 29 units per month.
That's where Module C comes in. Re-type all the numbers from Module A into the "hard" cells in Module C. Now, change the 29's to 26's. Now, in Module C's colored cells, you will see what your new price, burn rate, and unit costs must be, as well as a comparison to (i.e. the percentage changes from) your baseline case described in Module A. (And you can do that to re-calculate B/E volume too, helpful if you want to quickly see the percentage changes from the baseline case.)
In other words, Module C is basically a tool for sensitivity (or risk) analysis. It's nice if you can include a few scenarios in your business plan appendix (just cut-and-paste a couple times, right?).
Please let me know if there are any additional questions. -Chihmao.