Creating a Custom Tariff

Keystone Designer supports creating a custom tariffs or time-of-use rate schedules for behind-the-meter projects. Creating custom rate schedules enables matching your clients' specific utility bill calculation if their current tariffs vary from ones in the rate library or running scenarios based on proposed rate changes your clients might experience in the future. 

Custom tariffs are specific to your partner account and shared across all users licensed to the application. These rate schedules can be found at the top of the Tariff drop-down menu and are denoted by the "-Custom" suffix.

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Note: Tiered rate and CPP based rate structures are not currently supported in the custom tariff tool.

Creating a New Custom Tariff

Custom tariffs are built using a combination of seasons, times of use and rates. A progress bar at the bottom of the window will show a green check for each completed item and a red ! for any section that is incomplete.

Each section can be collapsed and expanded by clicking in the gray area around the timeline view or header text at the top of the section:

Seasons

Seasons denote portions of the year when rates or times of use change. If your custom tariff doesn't change seasonally, a single, year-round season serves as a high-level umbrella for any more granular time of use changes.

Seasons are specified by providing a name and setting the start and end month and day. Use one or more seasons to cover the full 12 months. For example, we can specify that the Summer season begins on May 1st and ends on September 30th and Winter begins October 1st and ends April 30th.

The timeline view at the top of the section will alert if there is an overlap or missing months. In this example, there are two alerts because both Summer and Winter include September, and no season is assigned to the month of March.

Times of Use

Time of use (TOU) periods denote different periods of the day during which different rates apply. TOU definitions include both the days of the week the periods apply and also the hourly intervals in which that TOU is active. Keystone Designer supports granular mixing and matching of hourly periods with different days of the week, but you can also simply describe a flat rate by using a single, day-long TOU that applies to all days of the week.

For each defined season, you must specify one or more TOU. By default, the first TOU you specify will apply to all days of the week.

In this example, for the Summer season there are two defined TOUs: On-Peak from 1 PM to 6:44 PM and Off-Peak from 6:45 PM to 21:59 PM for all days and holidays. TOUs can begin and end on the quarter hour. All end times are one minute earlier than start times to prevent overlapping intervals.

To create a special TOU that only applies to a subset of the days of the week (most commonly weekday vs weekend/holidays), Add a Day Group. Select multiple days for this group by using Ctrl + click in the dropdown provided.

By adding a day group of "Saturday, Sunday and Holidays" with a single "All-Day" TOU to the previous example, the result is two TOUs during the week and a single TOU for weekend and holidays.

As with the seasons, the interface will alert if there are overlapping or missing TOUs. This example shows that nothing is defined from 9 AM to Noon during the week.

Rates

The custom rate designer allows the addition of TOU demand and consumption rates, non-coincident and stacked demand charges, energy items, and services charges.  At the minimum, consumption rates are needed for each defined TOU. Rates should be added in the local currency of the utility. The conversion rate to translate the local currency of the rate to USD in the full analysis can be defined within the scenario editor. 

Optional Non-Coincident and Stacked Demand Charges

Non-Coincident charges are based on the highest monthly demand, regardless of TOU.

Stacked demand charges apply to multiple TOUs. The stacked demand charge will be multiplied by the highest max demand out of the selected TOUs.

Optional Energy Items and Service Charges

Energy items are applied to every kWh at any TOU or season and can be marked non-bypassable for accurate net energy metering (NEM) modeling. Non-bypassable items are not refunded if solar energy is exported to the grid.  Energy items can also include credits by entering a negative cost/kWh.

Service Charges have the option of specifying a kW range by adding one service charge for each kW range as in the example below. When running a scenario with a kW-based service charge, Keystone Designer will apply the service charge based on the highest kW seen within the full energy use profile. Service charges with minKW of 0 and no value for maxkW will apply to all possible kW ranges.

Copying and Modifying an Existing Tariff

For some users, beginning with an existing tariff and making a few minor changes may be the fastest way to create a new custom tariff. To begin with an existing tariff, first choose View next the utility tariff in the Tariff dropdown menu.

A Copy button will appear in the right corner of viewing window if that tariff is eligible for duplication. 

Rename the custom tariff and make any desired modifications. Click Save to complete and view the modified tariff. The new tariff will appear in the Tariff drop-down as a custom tariff for all users associated with your account.

Note: Some service charges and energy items may appear as a consolidated number compared to the detailed line items in the tariff documentation provided by the utility company.