PPA Price and Time-of-Delivery Adjustment Factors

For projects with utility financing, you may notice that the PPA price that SAM reports in the Metrics table on the Results page is not the same as the PPA Price in Year One of the project cash flow.

The two values are different when you specify a set of time-of-delivery (TOD) adjustment factors. When your analysis involves TOD factors, the price in the Metrics table is the price you would use in a bid, and the price in the cash flow table is the average of the TOD-adjusted hourly PPA prices for the first year.

When you create a new case for a CSP system in SAM (except dish-Stirling), it includes a set of TOD factors by default. To remove the factors from your analysis, choose "Uniform Dispatch" for the dispatch schedule library.

The PV systems do not include TOD factors by default.

The TOD factor inputs are on the following pages for the different technologies:

- Trough, tower, and generic solar: Thermal Storage page
- Linear Fresnel: Power Cycle page
- PV and other: Energy Payment Dispatch

For a description of the TOD factors in SAM's help system, see the following topics: Financing, Energy Payment Dispatch, and Metrics Table Variables, PPA Price.

The following California Energy Commissions's consultant's report (2006) discusses the TOD factors used in California: www.energy.ca.gov/2006publications/CEC-300-2006-015/CEC-300-2006-015.PDF .

You can find more recent TOD schedules by searching the Web for "payment allocation factor."

Best regards,
Paul.