One of the biggest challenges in using a model like HOMER is finding the numbers to put into it. This page is meant to help you find the information you need. If you know of any other helpful sources, please let us know so we can add them. Note that NREL cannot guarantee the accuracy of any data from external sources, and does not endorse any manufacturer or retailer.
Electric Load Data
The only source of hourly load data that we're aware of is the DG Marketplace, which you can visit at www.dgmarketplace.com. This website sells typical residential, commercial, and industrial load data for locations across the US.
To find your time zone, check www.worldtimezone.com.
Solar Radiation Data
HOMER will accept 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. One of the best sources of solar radiation data is the TMY2 and TMY3 data sets provided for free by the US National Renewable Energy Laboratory. You can import TMY2 and TMY3 files directly into HOMER's Solar Resource Inputs window.
- NREL provides TMY2 data at: http://rredc.nrel.gov/solar/old_data/nsrdb/tmy2/).
- And TMY3 data at: http://http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/).
- NASA's Surface Solar Energy Data Set provides monthly average solar radiation data for everywhere on earth at http://eosweb.larc.nasa.gov/sse/.
- In the Solar Resource Inputs window if you specify monthly data there is a button labeled "Get Data Via Internet". If you are connected to the Internet, that button retrieves monthly solar data for the specified latitude and longitude from NREL's and NASA's satellite databases. Give that a try, it's really handy. If you specify a lat/long outside North America, HOMER refers to the NASA SSE dataset. So depending on what location you request data for, HOMER might ask you to specify a username for NASA on their SSE website. Please use firstname.lastname@example.org as your NASA SSE username in HOMER2. NASA recently re-configured their website and eliminated the need to validate specific email addresses. To enter this in the HOMER software, open HOMER2, select File >> Preferences, and enter email@example.com into the field for NASA SSE username.
- This help file contains a table of monthly solar data for selected worldwide locations.
- The South African Renewable Energy Resource Database provides solar, wind, hydro, and biomass resource data at www.csir.co.za/environmentek/sarerd.
- The US Renewable Resource Data Center provides US data and maps at http://rredc.nrel.gov/solar.
- The World Radiation Data Center provides worldwide solar data at http://wrdc-mgo.nrel.gov. Note that data from this website need a lot of processing to be useful in HOMER.
Wind Speed Data
It can be difficult to obtain measured wind speed data. Proper measurement of wind speed is expensive and time consuming, and 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 www.eere.energy.gov/windpoweringamerica/wpa/wind_maps.asp.
- The Canadian Wind Atlas is available at www.windatlas.ca.
- The Brazilian Wind Atlas is available at www.cresesb.cepel.br/atlas_eolico_brasil/atlas-web.htm.
A number of other websites provide wind speed
- The US Renewable Resource Data Center provides information on wind data at http://rredc.nrel.gov/wind.
- The website www.weatherbase.com provides monthly average wind speed data for many cities around the world.
- The Windustry website maintains a list of US wind data resources at www.windustry.com/resources/windmaps.htm.
- The US National Climatic Data Center provides monthly average wind speed data for many US cities at www.ncdc.noaa.gov/ol/climate/online/ccd/avgwind.html. To convert from mph to m/s, divide by 2.23694.
- The Technical University of Denmark maintains a database of wind characteristics at www.winddata.com.
Renewable Power System Components
Several retailers sell components for renewable power systems . The website www.ecobusinesslinks.com 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. Check out:
- Real Goods at www.realgoods.com
- The Alternative Energy Store at www.altenergystore.com
- SolarEnergy.com at www.solarenergy.com
- The Solar Biz at www.thesolar.biz
- The Energy Development Co-operative at www.unlimited-power.co.uk
Other sources of cost and performance data for renewable power system components include:
- The California Energy Commission, at www.energy.ca.gov/distgen/economics/economics.html
- The Renewable Energy Technology Characterizations, a detailed report on the performance and costs of solar, wind, and biomass power systems, available at www.eere.energy.gov/power/techchar.html. This report even 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 at www.solarbuzz.com.
- Wind Power Online, an online marketplace for wind turbines at www.windpoweronline.com.
- 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, available at www.eea-inc.com/dgchp_reports/TechCharNREL.pdf.
- The Distributed Generation Information Center provides summary technical and economic data on reciprocating engine generators, microturbines, and fuel cells, as well as a large library of links, at www.distributed-generation.com.
The US Environmental Protection Agency provides emissions coefficients for CO2, SO2, and NOx for US locations at their Power Profiler website at www.epa.gov/cleanenergy/powpro/screen1.html.
The EPA's eGRID website contains even more emissions data, including state-by-state average emissions factors for all the pollutants that HOMER models.
- This help file contains a table of US grid emissions factors.
- Additional data is available The EPA document Emissions Factors, Global Warming Potentials, Unit Conversions, Emissions, and Related Facts, November 1999, at www.epa.gov/appdstar/pdf/brochure.pdf.
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 www.eere.energy.gov/greenpower/markets/netmetering.shtml
- For a list of renewable energy incentives across the United States, see the Database of State Incentives for Renewable Energy at www.dsireusa.org.