Time-of-delivery (TOD) factors are a set of multipliers that apply to the PPA price so you can model a situation where the PPA price changes on an hourly, subhourly, and/or seasonal basis.

There are two ways to define TOD factors:

TOD factors by schedule

Use this option to define the factors using up to nine TOD periods with hour-by-month weekday and weekend schedule matrices, or to choose TOD schedules from a library of data.

TOD factors by time step

Use this option to assign a TOD factor to each simulation time step. For example, if you are running hourly simulations, you can assign a different TOD factor to each hour of the year.

SAM calculates the PPA price for each hour by multiplying the Year 1 PPA price shown in the results Summary page by the TOD factors you define for each of up to nine periods.

Important Notes!
 
If your analysis is for a project with a fixed PPA price that does not vary with time of day or month of year, use the TOD Factor by Schedule option, select Uniform Dispatch in the library and click Apply values from library to ensure that all of the PPA multiplier values are set to one.
 
When you click Apply values from library, SAM replaces the TOD data with data from the library. If you are using your own TOD data, you can use the Save data to file button at the bottom of the Time of Delivery Factors page to save your data.

Download forecast price data from Cambium

If you do not have time series price data for your analysis, you can download hourly marginal cost data for modeled futures of the U.S. electricity sector from the NREL Cambium database. SAM runs the Cambium Time Series Prices macro, which prompts you to choose from the available price data, and then automatically sets the following inputs:

•Chooses the Specify PPA price option.

•Sets PPA price to $1/kWh

•Chooses the TOD factors by schedule option

•Converts the price data from $/MWh to $/kWh and set the TOD factors by time step to the downloaded price data.

For a discussion of how to use Cambium modeled price data in your analysis, see https://emp.lbl.gov/publications/integrating-cambium-marginal-costs.

To populate values from the library:

1.Choose TOD factors by schedule.

2.Click a row in the library.

3.Click Apply values from library.

To specify your own TOD factors by schedule:

1.Choose TOD factors by schedule.

2.Type a PPA price multiplier value for up to nine periods.

3.Use the schedule matrices to define the hour and month for each period as described below.

To specify your own TOD factors by time step:

1.Choose TOD factors by time step.

2.Click Edit data and enter your TOD factors in the table.

To download price data from the Cambium database:

1.Click Download forecast price data from Cambium and follow the prompts.

About TOD Factors by Schedule

TOD factors

For each of the nine periods in the list, to calculate the PPA price in a given period, SAM multiplies the Year 1 PPA price by the multiplier you specify. For example, if Period 1 is the summer peak, defined as Noon to 7 p.m. in June through September with a multiplier of 2.38, and the Year PPA price is 6 cents/kWh, the price that the project would receive for each unit of energy it sells during those summer peak hours would be 6 cents/kWh × 2.38 = 14.28 cents/kWh.

Weekday Schedule, Weekend Schedule

The weekday and weekend matrices allow you to associate each of the nine periods with a time of day and month of year. To use the matrices, for each period, draw a rectangle on the matrix with your mouse, and type the period number with your keyboard. See Weekday Weekend Schedules for details.

About the TOD Schedules and Factors Library

The TOD Schedules and Factors library stores a selection of TOD data that you can use to explore different scenarios if you do not have data from another source. You can also use one of the library schedules as a starting point and modify it to meet your requirements. Remember to click Apply values from library to use data after you click a row in the library list.

The library is stored as a CSV file in the libraries folder of your SAM installation. For details about how to access the file, see Libraries.

Uniform Dispatch

This option removes TOD factors and schedules. Use this when the PPA price does not vary with time of day or month of year.

Generic Summer Peak

This is a fictitious schedule with a June - September summer peak period and six TOD periods representing baseline, shoulder, and peak daily prices with with peak prices in summer afternoons.

Generic Duck Curve

This is a fictitious schedule representing a basic "duck curve" shape with three TOD periods for a baseline night-time prices, peak evening prices, and low daytime prices.

Generic Low Carbon Duck Curve

This schedule is based on data from an NREL California low carbon grid study for 2030 assuming 50% of the state's electricity generation is from renewable energy sources. See Brinkman, G.; Jorgenson, J. (2016) Low carbon grid study: Analysis of a 50% emission reduction in California. National Renewable Energy Laboratory. NREL/TP-6A20-64884. (PDF 2.2 MB)

California PUC Advice Letter Data

For the 2015 and 2016 data in the library, the factors are from the following California Public Utilities Commission Renewable Auction Mechanism Program advice letters:

•PG&E 2016: Advice Letter 4780-E (January 22, 2016)

•SCE 2015: Advice Letter 3244-E (August 6, 2015)

•SDG&E 2015: Advice Letter 2717-E Attachment A (July 13, 2015)

Important Note about California TOD Data! PG&E and SDG&E offer different TOD options for projects that meet "energy only" or "full capacity deliverability" requirements, and SDG&E has options for "local" and "system" projects. Use your interconnection application and other documents to determine which TOD factors are appropriate for your project so you can choose the correct option in SAM.

For the 2009 and 2011 data, the factors are from the Market Price Referent (MPR) documents available on the California Public Utilities Commission website. The SAM library includes values from Appendix B of Resolution E-4442 (2011) and Resolution E-4298 (2009).

Time of Delivery Factors in Results

SAM reports hourly, monthly, and annual TOD-related results. You can view these results on the Data and Graphs pages.

Single Values

The single value results are available .

First year energy from the system in TOD period n

The total quantity of electricity delivered to the grid (and sold) by the system in Year one for each of the nine TOD periods, in kWh per year.

First year energy price for TOD period n

The power price for each of the nine TOD periods, equal to the product of the TOD factor for each period and the PPA price shown in the Metrics table.

First year revenue from the system in TOD period n

The dollar value of electricity sold by the project in Year one for each of the nine TOD periods, in dollars per year.

Monthly Data

The monthly variables are available on the Results page in Graphs and Tables.

First year energy from the system by month for TOD period n

The total quantity of electricity delivered to the grid (and sold) by the system in Year one for the given TOD period in each month, in kWh.

First year revenue from the system by month for TOD period n

Total dollar value of electricity sold by the project in Year one for each month.

Annual Data (All Years)

Note. The first row in the annual data table is equivalent to Year zero in the project cash flow, before the system starts generating electricity.

Energy produced by the system in TOD period n

The total amount of electricity delivered to the grid (and sold) by the system in each year of the analysis period for each of the nine TOD periods.

Revenue from the system in TOD period n

The total dollar value of electricity sold by project in each year of the analysis period for each of the nine TOD periods.

Capacity payments are is an annual payment to the project for available capacity. SAM reports the annual capacity payment revenue in the project cash flow.

Note. If your project does not involve capacity payments, set Capacity payment amount to zero.

Capacity basis

Specify the annual capacity payment as a dollar per megawatt value with the capacity credit specified as a percentage of the system nameplate capacity. See the system nameplate description below.

Fixed amount

Specify the annual capacity payment as a dollar amount.

Capacity payment amount, $/MW or $/year

When you choose the capacity basis option, enter a $/MW value in Year 1 dollars for the annual capacity payment.

Note. SAM assumes the capacity payment rate in $/MW is an annual rate. If you are given a daily or monthly rate, you should convert it to an annual rate. For example, a $100/MW daily rate would be equivalent to $36,500/MW annually. Similarly, a $100/MW monthly rate would be $1,200/MW annually.

When you choose the fixed amount, enter a $ value in Year 1 dollars for the annual capacity payment.

You can also click and then Edit to use the Edit Schedule window to enter a different payment amount for each year of the analysis period instead of a single value.

Capacity payment escalation

The annual escalation rate applies to the annual capacity payment in Years 2 and later. If you expect the capacity payment amount to increase from year to year, enter the escalation rate as an annual percentage.

The capacity payment escalation rate is disabled when you choose the Schedule option to enter annual values for the capacity payment amount.

Capacity credit (eligible % of nameplate), %

The percentage of the system's nameplate capacity that is eligible for capacity payments when you choose the Capacity basis option. If this value is zero, no capacity payments will be made.

For systems with battery storage that earn a capacity payment based on the battery's capacity in kW (maximum discharge power), you can use the capacity credit percentage to represent the battery capacity. For example, for a PV-battery system with a 100 MW array and 60 MWac battery, you could set the capacity credit percentage to 60.

System nameplate, MW

The system's nameplate capacity. Note that the nameplate capacity is defined differently for different kinds of systems. For example for photovoltaic systems, the nameplate capacity is the total DC array capacity, and for wind and concentrating solar power systems, it is an AC capacity.

Battery maximum discharge power, MWac

For systems with battery storage, the battery's maximum discharge power from the Battery Cell and System page.

For PV Battery and Custom Generation Profile - Battery configurations, SAM shows this battery capacity value for reference, but does not use it to calculate the capacity payment amount.

For Standalone Battery configurations, SAM uses the battery maximum discharge power to calculate the capacity payment amount.

Curtailment payments generate revenue in addition to energy payment or PPA revenue during times when the project is required to reduce or stop electricity generation by the electricity off-taker.

Use the grid curtailment inputs on the Grid page to define the curtailment schedule.

Curtailment Compensation

Curtailed energy compensation, $/kWh

The compensation rate in dollars per kWh of curtailed energy.

You can specify a single compensation rate as a Year 1 value with optional escalation rate, or click Sched and Edit to specify a compensation rate for each year using the Edit Schedule window.

For each hourly or subhourly time step, the curtailed energy is the system's power output minus the curtailment limit from the curtailment table on the Grid page. The annual curtailed energy is the sum of the hourly or subhourly curtailed power values over one year. SAM shows the annual curtailed energy amount for each year in the project cash flow.

Curtailed compensation escalation, %/year

The curtailment compensation escalation rate applies to the curtailment revenue in Years 2 and later when you specify the compensation rate as a single Year 1 value. SAM does not apply the inflation rate from the Financial Parameters page to the curtailment compensation rate.