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Importing a Load from a Time-series File

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You can import a load from a time-series file using one of several formats that HOMER Grid recognizes.

Tip: You can import data with any time step down to one minute. HOMER detects the time step based on the number of rows in the file. For example, if the data file contains 8760 lines, HOMER assumes it is hourly data. If the data file contains 34,350 lines, HOMER assumes it is 15-minute interval data.

On the Electrical page:

Click the Import... button to quickly import a simple time series file.

Click the Import and Edit... button to import data files with gaps in the data or an incorrect number of rows. This function includes basic gap-filling tools to fill in missing data points.


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 so the modifications are 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.

The following are descriptions of the formats HOMER recognizes: 1) Two Column Format, 2) Three Column Format, 3) Green Button Format, 4) Utility API Format, 5) Day By Row, and 6) Single Column of Values.

Option 1: Two Column Format



Option 2: Three-column Format




Option 3: Green Button Format



Option 4: Utility API Format


Option 5: Day By Row



Option 6: Single Column of Values

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. The following is an example input file.


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. 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

Note: Natural resources generally do not have weekend/weekday bias (for example, wind speed is no higher or lower, on average, on weekends than weekdays).

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). If none of the conditions above apply to your model, you might be able to leave your load data as is, even if it does not start on a Monday.





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