Dear Julien, The discount rates in the LCOE equations make a little more sense if you follow the derivation of the equations. Please see the Help topic on LCOE under "LCOE Definition" for a description:
SAM Help -- Levelized Cost of Energy
Thank you for pointing out the typos in the spreadsheet. We will fix those for the next release of SAM.
(By the way, when I see HTML code in a post, as in yours above, I can edit the message after you post it to change the formatting so that they appear correctly.)
Best regards,
Paul.