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Finding Data to Run HOMER

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One of the biggest challenges in using a model like HOMER is finding the numbers to put into it. This section of the help is a guide for finding the information you need. If you know of any other helpful sources, please let us know so we can add them.

Note: We cannot guarantee the accuracy of any data from external sources, and do not endorse any manufacturer or retailer.

Electric Load Data

We are aware of only one source of hourly load data, the DG marketplace. This website sells typical residential, commercial, and industrial load data for locations across the US.


To find your latitude and longitude, check For help with Google Maps, see the Latitude and longitude coordinates Google Support article.

To find your time zone, check

Solar Radiation Data

HOMER accepts solar radiation data as monthly averages or as a time series. Time series solar radiation data is most commonly available with an hourly time step, but HOMER can accept any time step down to one minute. Two of the best sources of solar radiation data are the TMY2 and TMY3 data sets provided for free by the US National Renewable Energy Laboratory (NREL). You can import TMY2 and TMY3 files directly into HOMER's Solar Resource Inputs window.

NREL provides TMY2 data at

NREL provides TMY3 data at

NASA's Surface Solar Energy Data Set provides monthly average solar radiation data for everywhere on earth at

The Published Solar Data section of the help contains a table of monthly solar data for selected worldwide locations.

The US Renewable Resource Data Center provides US data and maps at

The World Radiation Data Center provides worldwide solar data at The data from this website need a lot of processing to be useful in HOMER.

GeoModel Solar has many solar data sets available at various resolutions:

Wind Speed Data

It can be difficult to obtain measured wind speed data. Proper measurement of wind speed is expensive and time consuming. Average wind speeds can vary markedly over short distances because of terrain effects. For these reasons, it is often necessary to synthesize wind data from estimated monthly average wind speeds.

Many countries have published wind atlases:

Wind maps for many US states are available at

The Canadian Wind Atlas is available at

The Brazilian Wind Atlas is available at

A number of other websites provide wind speed data:

The US Renewable Resource Data Center provides information on wind data at

The website provides monthly average wind speed data for many cities around the world.

The Windustry website maintains a list of US wind data resources at

The US National Climatic Data Center provides monthly average wind speed data for many US cities at To convert from mph to m/s, divide by 2.23694.

The Technical University of Denmark maintains a database of wind characteristics at

Renewable Power System Components

Several retailers sell components for renewable power systems. The website maintains a list of renewable power retailers around the world. A few have very helpful websites providing cost and performance data for PV panels, wind turbines, hydro turbines, batteries, converters, and other system components. See the following websites:

Alternative Energy Store


Solar Biz

Energy Development Co-operative

Other sources of cost and performance data for renewable power system components include:

Renewable Energy Technology Characterizations, a detailed report on the performance and costs of solar, wind, and biomass power systems. This report includes predictions of future performance and costs out to the year 2030.

SolarBuzz, which provides price data for PV modules, inverters, batteries, and charge controllers.

The EPA provides a prices and references for renewable technologies at


A very useful document covering the technology, emissions, and costs of natural gas-fired reciprocating generators, microturbines, fuel cells, and Stirling engines is the Gas-Fired Distributed Energy Resource Technology Characterizations.


PV WATTS v.1 is a simple and useful tool for estimating a PV derating factor.


The following provide emissions information:

The US Grid Emissions Factors section of the help contains a table of US grid emissions factors.

The US Environmental Protection Agency provides emissions coefficients for CO2, SO2, and NOX for US locations at their Power Profiler website at

The EPA's eGRID website contains even more emissions data, including state-by-state average emissions factors for all the pollutants that HOMER models.

Additional data, such as The EPA document Emissions Factors, Global Warming Potentials, Unit Conversions, Emissions, and Related Facts, November 1999, can be found at

Policies and Incentives

The following provide information about policies and incentives:

For information on current net metering policies across the Unites States, see the US Department of Energy web page on the topic at

For a list of renewable energy incentives across the United States, see the Database of State Incentives for Renewable Energy at