Solar and Wind Energy Resource Assessment (UNEP)
Detailed information about levels of solar radiation around the world may be seen on a set of maps prepared by the United Nations Environment Programme (UNEP). The instructions provided are not very clear so this page attempts to explain how to use this information.
The view the information, click on SWERA maps. Hold down the CTRL key if you would like the maps to appear under a new tab—so that you can switch easily between the maps and this page.
Different maps and scales may be selected from the drop-down menus at the top of the screen. It is possible to zoom in or out using the buttons at the top left.
The fourth icon from the right at the top of the screen will bring up a list of data sources on the left. If you click the tick box for any one of them, corresponding data will be plotted on the map to the right. It is usually best to show one set of data at a time although it is possible to show two or more at the same time.
The words 'high', 'mod' or 'low' in the name of each data source refers to the level of resolution of the data. 'DNI' = 'Direct Normal Irradiance' (CSP); 'GHI' = 'Global Horizontal Irradiance' (PV); 'LTI' = 'Latitude Tilt Irradiance' (PV).
Click '+' to the left of any data source to reveal a key to the colours or symbols on the map or click '+' next to 'Layers' at the top left to show them all at once. Units for solar radiation appear to be kWh/m2/day.
To see time series (monthly plots) for any one small area, click on 'Query Time Series' at the top of the screen. The cursor will change to an arrow with a question mark next to it. Click on the spot that you are interested in and monthly plots will be shown in a new window. It is possible to change the data sources for these monthly plots or plot two or more at the same time by checking the appropriate tick boxes and clicking the 'Refresh' button near the bottom right.
To see monthly averages for the given small area plotted on a map, click on any one data point in the time series and a corresponding map will appear near the bottom of the screen. There are buttons that allow you to select months individually or cycle through them manually or automatically.
Last updated: 2009-08-20