Dear Readers: We are trying something new with the HOMER newsletters, starting immediately. Instead of one long email each month, we'll be sending out shorter but somewhat more frequent communications. This will keep you updated on our training and travel schedule better, and give you more chances to sign up for the free webinars that we are currently planning.

This newsletter features a tip for HOMER users, helping you get more from your software.

One of HOMER's strengths is giving you multiple options for resource and load data. We receive a lot of questions about what solar resource data are best for use in HOMER. This month's tip answers these questions.

The solar resource data set in HOMER is typically input as global solar radiation on the horizontal surface (Global Horizontal Irradiance or GHI). This includes both direct normal and diffuse radiation. It is expressed in kWh/m^2. There are three ways that you can get solar GHI data into HOMER:

1. Use the "Get Data Via Internet" button in HOMER. Based on the latitude and longitude you provide, this button accesses our online database that serves up data from either NREL's Climatological Solar Radiation (CSR) or NASA's Surface meteorology and Solar Energy (SSE) data set. The CSR dataset is used preferentially because it has finer surface resolution, although it only provides data for about 25% of the earth. If CSR data is not available, SSE data is used.

2. Import your own time-series datasets. From the solar resource window in HOMER, select the "Import time series data" button, then the "Import file" button. Your 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 solar radiation (GHI in kW/m2) for that time step.
3. For United States locations, you can directly import the "Typical Meteorologic Year" datasets available from NREL (TMY2 and TMY3). HOMER will extract the proper information from TMY2 or TMY3 data. We recommend the simplified version of the TMY2 datasets available for download from the Sample Files page on our website.
4. Synthesize hourly data from monthly averages. Typically, since solar resource data are available for most of the earth, we recommend you use one of the other two techniques to put a solar resource into HOMER. However, HOMER will allow you to do to enter your own data by month, using either the average daily GHI solar radiation or the average clearness index. The clearness index is the ratio of GHI to the extraterrestrial radiation that hits the top of the atmosphere at that latitude. It is a value between zero and one that is very intuitive as the average cloudiness. Typical values for selected locations around the world are in the Help section of HOMER.

Do you have a tip for HOMER users? If so, please share it with us in the HOMER users community here.

The fastest way to get HOMER support and to answers your questions is to check our searchable Knowledgebase, built from over 1600 user questions and answers. It's available 24/7 at:

http://support.homerenergy.com/index.php?/Knowledgebase/List.

Do you have an analytical need that needs to be treated a little differently from the public version of HOMER? We create custom and enhanced versions of HOMER for specific needs. Let us know if we can help. Contact us at +1-720-565-4046 or consulting@homerenergy.com to learn more.