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HOMER Pro 3.9

Navigation: Design > Load Tab > Adding a Load

Importing a Load from a Time-series File

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To import a file, you must prepare a text file that contains the electric load in each time step for a complete year.

Tip: You can import data with any time step down to one minute. HOMER detects the time step when you import the data file. For example, if the data file contains 8760 lines, HOMER assumes that it contains hourly data. If the data file contains 52,560 lines, HOMER assumes that it contains 10-minute data.

The data file must contain a single value on each line, where each line corresponds to one time step. Each value in the file represents the average load (in kW) for that time step. The first time step starts at midnight on Monday, January 1st. A sample input file appears below.

Tip: In HOMER, January 1st is always a Monday.


The Import... button on the Electrical, Thermal, or Hydrogen load pages allows you to quickly import a simple time series file. The Import and Edit... button can import data files with gaps in the data or an incorrect number of rows. The Import and Edit... function includes basic gap-filling tools to fill in missing data points.


Because the HOMER standard year starts on a Monday, you might need to adjust your load time series to match. If any part of your HOMER model is sensitive to weekdays versus weekends (i.e., a grid rate schedule with different prices on weekends and weekdays), you may need to modify your load data so the first day is a Monday. Of course, natural resources in general have no weekend/weekday bias (for example, wind speed is no higher or lower, on average, on weekends compared with weekdays). The following are examples of weekday/weekend sensitivity:

Imported grid outage time series with weekend or weekday bias

Imported grid real-time rates with weekend/weekday differences

Thermal, hydrogen, or other electric loads with weekend/weekday differences

Imported biomass resource time series with weekend/weekday bias

Generators and electrolyzers with an operation schedule (forced on, forced off, or optimized) with weekend/weekday differences

If none of the above conditions apply to your model, it may be safe to leave your load data as-is, even if it does not start on a Monday. Otherwise, you can usually adjust your data to start on a Monday by cutting a few days from the beginning of the load profile and pasting them at the end (or vice versa).

Note: If you view the hourly time series plot for your simulation, your load will be shifted by the number of days you moved.

When you import data from a text file, HOMER makes a copy of the data set and integrates it with the HOMER (.hmr) file. After the data is part of the HOMER file, HOMER no longer refers to the original text file. If you modify data in the original file, you must import the modified file in order for the modification to be included in the HOMER file. After you import a data file, HOMER calculates the average 24-hour load profile for the whole year, and displays it in the table and graph. HOMER also displays the name of the imported data file in the title of the load profile graph.

If you click "Enter daily load profile(s)" after importing data from a file, HOMER discards the data from the imported file and synthesizes new data based on the twelve monthly average load profiles it calculated from the imported data. You can edit synthesized data by selecting the month and changing values in the load profile table. To edit values from an imported file, you must edit the file directly and then import the modified file, as described above.