There are two ways to add a Solar GHI and temperature resource: You may download the National Renewal Energy Lab's monthly GHI averages and/or NASA temperatures or choose to upload your own solar or temperature data.
HOMER uses the location for several aspects of the Solar production calculation, so it is important to specify the location even if you are not downloading solar data. This step can be completed in the Setup page in HOMER Front.
Download Solar and Temperature Data
Solar Resources may be pulled from the integrated database. The baseline data is a one-year time series representing the average global solar radiation on the horizontal surface,expressed in kWh/m2, for each time step of the year.
NREL data is available for certain parts of North America and has more granularity than the NASA database. If available, HOMER will use the NREL database; otherwise, the NASA data will be used in the solar production calculation.
Upload Solar and Temperature Data
If you selected Upload annual GHI Timeseries or annual temperature timeseries, you can prepare your own text file containing the data in each time step for a complete year.
Tip: You can import data with time steps of many sizes between 60 minutes and one minute. HOMER detects the time step when you import the data file. For example, if the data file contains 8760 lines, HOMER assumes it contains hourly data. If the data file contains 52,560 lines, HOMER assumes it contains 10-minute data.
The data file must contain a single value on each line, corresponding to one time step. Each value in the file represents the average solar radiation (in kW/m2) or annual temperature for that time step. The first time step starts at midnight on January 1st. The following is a sample input file.
You can import a text file with any extension or a CSV file. When you import data from a text file, HOMER makes a copy of the data set and integrates it with the HOMER (.hfront) file. After you import a data file, HOMER calculates monthly average radiation and clearness index values and displays them in the table and graph. HOMER also displays the name of the imported data file in the title of the graph.
See Also
How HOMER Calculates the PV Array Power Output
How HOMER Calculates the PV Cell Temperature
How HOMER Calculates the Radiation Incident on the PV Array
