Vastly different payback periods for same system between SAM Versions 2016.3.14 & 2016.3.14_R1

Hi All,

Has anybody experienced different payback periods for exactly the same system/file between SAM 2016.3.14 & SAM 2016.3.14 Revision 1?

I have a system that in the earlier version had a payback of 16.8 years but with Revision 1 has a payback of 10.6 years. Energy output, capacity factor and energy yield are exactly the same so I am guessing something has changed in the financial modelling although nothing is listed in the revision change notes to that effect.

File attached. NREL can you please look at this file in both versions and see what is going on?

Thanks,
Robert

Dear Robert,
In SAM 2016.3.14 Revision 1, we fixed three problems with the electricity bill calculation: 1. Correctly apply escalation rate to all rate categories (energy, demand, and fixed charge), 2. Correctly apply tiered demand charges, and 3. Fix a problem with kWh/kW demand charge units. These and other changes are listed in the release notes , which you can also access from SAM's Help system.
In your file, the electricity rate escalation rate of 5%/year was not correctly applied in the original SAM 2016.3.14 version. The results in Revision 1 should correctly account for the effect of the escalation rate.
Best regards,

Paul.

Thanks Paul.

ausfrosty - Thanks so much for asking this question. I was just about to freak out because I was having the same problem. I use a cloud drive and was so confused why I was getting drastically different results on my desktop vs. my laptop.