Welcome to NREL's PVDAQ photovoltaic performance database!
The PVDAQ website provides a public interface to some of the PV performance data contributed to NREL. Questions about the site contents or about potentially contributing to the database can be made by selecting the “Contact Us” link at the top of the site.
Metadata about each system is shown after selection of a system. Metadata describes the design of the system and does not include performance measurements. Some contributors have elected to maintain certain metadata as confidential. All publically available information will be displayed.
Upon selection of a system the performance data for that system is displayed. The graphs show several PV performance and diagnostic parameters and are based upon the international performance monitoring specification, IEC 61724:1998. The five parameters chosen for inclusion are:
Array Yield
Array yield describes the DC energy output of the PV array (kWh) per kilowatt (kW) of installed PV over the selected time period, t. This calculation does not include losses related to the conversion from DC to AC. Units are kWh/(kWp*t).For example:
- t = 1 day (24 hour period)
- 6.3kWh of DC energy production
- 2.0kWp of installed PV
- YA = 6.3kWh / (2.0kWp * 1 day) = 3.15 kWh/(kW*d)
System Final Yield
System final yield describes the AC energy output of the PV system (kWh) per kilowatt (kW) of installed PV over the selected time period, t, including all losses related to the conversion from DC to AC. Units are kWh/kWp/t.For example:
- t = 1 day (24 hour period)
- 6.0kWh of AC energy production
- 2.0kWp of installed PV
- YF = 6.0kWh / (2.0kWp * 1 day) = 3.0 kWh/(kW*d)
Array Performance Ratio
The array performance ratio is not specifically included in the IEC 61724:1998 standard. It is a measure of how losses affect the performance of the array. Losses may include incomplete conversion of available irradiation, array temperature effects, and PV module component inefficiencies and failures. The performance ratio of the array is the ratio of the array yield ( kWh/(kWp*t) ) to the reference yield, YR, (total irradiation per unit time, t, divided by the reference in-plane irradiance). The reference yield results in the number of peak sun hours per unit time ( (kWh/t)/kWp = h/t ).
Array performance ratio is dimensionless.For example, for a 1 day period:
- YA = 3.15 kWh/(kW * 1day) = 3.15h/d
- YR = 4.00kWh/(m2 * 1day) / 1kW/m2 = 4.00h/d
- RPA = YA / YR = 3.15h/d / 4.00h/d = .78
System Performance Ratio
The system performance ratio is a measure of how losses affect the performance of the system as a whole. Losses may include incomplete conversion of available irradiation, array temperature effects, and both PV module and balance-of-system component inefficiencies and failures. The performance ratio of the system is the ratio of the final system yield ( kWh/(kWp*t) ) to the reference yield, YR, (total irradiation per unit time, t, divided by the reference in-plane irradiance). The reference yield results in the number of peak sun hours per unit time ( (kWh/t)/kWp = h/t ).
System performance ratio is dimensionless.For example, for a 1 day period:
- YF = 3.15 kWh/(kW * 1day) = 3.15h/d
- YR = 4.00kWh/(m2 * 1day) / 1kW/m2 = 4.00h/d
- RPS = YF / YR = 3.00h/d / 4.00h/d = .70
Availability of Monitoring Data
The availability of monitoring data describes how much of the expected data is available for calculations during the indicated time frame and is represented by a percentage. For instance, if the system is sampled every one minute and the time interval of interest for calculations is one hour than we would expect 60 measurements to be available. If 59 of the 60 measurements are in the database then the availability of monitoring data for this time period is (59/60) * 100 = 98.3%.
Controlling Layers
The Layers tab in the left-hand column allows you to select the data you want to display on the map. Click in the checkboxes to choose each data type. Icons or shaded regions, matching those in the layer list, will appear on the map. To expand or collapse a data folder, click on the + or - box next to the folder.
Right-click on a data selection (for example, E85) to quickly set legend and transparency options or view the data source.
The order in which layers (or groups of layers) are drawn on the map can be modified by clicking on a layer or folder and dragging it higher or lower in the list. On the map, layers higher in the list will be rendered on top of layers lower in the list.
Viewing the Legend
The Legend tab in the left-hand column allows you to refine the data you want displayed on the map.
Legend information exists for each layer drawn on the map, and allows you to create custom layer styles
(changing colors; hiding classes).
Click in the checkboxes to remove or add a data class, or click on the
colored boxes (or lines/points) to change the color, then click Apply.
Click Reset All Layers
to return the legend to the default setting.
Panning the Map
The Pan tool allows you to move the map around your screen.
Click on Pan in the top menu bar to turn your cursor into a hand. Click and drag your mouse
on the map to move the map around the screen.
To turn off the Pan tool, select another
tool (Zoom or Measure).
You can also pan around the screen by clicking on the arrows in the upper left-hand corner of the map.
Zooming the Map
This tool allows you to zoom in on the map. Click on Zoom in the top menu bar. Your cursor will turn into a magnifying glass. Drag a box over the area that you wish to zoom to. To turn off Zoom, select another tool (Zoom or Measure).
You can also zoom in or out by clicking on the + or - scale in the upper left-hand corner of the map.
Reset the Map
Clicking Home returns the map to default, full U.S. map view. Your layer and legend selections will stay the same.
Using the Measure Tool
This tool allows you to measure the distance between points in either miles or kilometers.
To measure between points on the map, click Measure in the top menu bar. Select either
miles or kilometers. Single-click on a starting point. Drag your mouse to an ending point and
double-click to release the Measure tool. The distance between the points will appear
in the Measurement Totals box.
Closing the Measurement Totals box to turn off the Measure tool.
Printing the Map
Click Print in the top menu bar to print the map on the screen. A new window will open. Add a title to the map and click the Print button.
Use the mouse to click and drag the map to re-center it on the page. This is useful for users with large monitors.
Note for Internet Explorer Users: Internet Explorer cannot print transparent images. If your map contains partially transparent layers (layers that allow other map features to show through them) those layers will be completely opaque in the printed output. The Firefox browser does not have this limitation.
Finding Locations
The Find Location tool allows you to search for a specific location on the map. Enter the location and click OK. The map will zoom to the geographical center of the location you input.
Address entry formats:
- Street address, City, State, Zip code
- City, State, Zip code
- City, State
- Zip code
Lat/Long entry formats:
- 39.73 -104.98
- 39° 44' N 104° 59' W
- 39 44 N 104 59 W
Identifying Features
The Query tool allows you to retrieve data about a specific spot or region on the map.
By Point: When you query By Point, your arrow cursor will appear with a small "i" next to it. Click on a specific icon or shaded region on the map. A Query Results box will appear with the data related to that specific point. If there is more than one piece of data at that point, a box will appear allowing you to select a specific type of data.
By Region: When you query By Region, your arrow cursor will appear with a small "i" in a box next to it. Click and drag your mouse over the region you would like to query. The map will zoom into that region. Black spots will appear on the map over the locations from which data is pulled.
The data for each of the locations will appear in a data window pane at the bottom of the screen. Click on the tabs at the top of the data pane to view the results for each data type (Biodiesel, E85, etc.). Click on the small arrow box at the upper right of the data pane to collapse and reopen the pane.
To download the data to an Excel spreadsheet, click the Download button at the top of the data pane. A message may appear asking you to confirm the file type before importing it to a spreadsheet.
Clear Overlays: This option clears the black data indicator spots from the screen.
Using the Advanced Query Tool
Changing the Base Layer
In the right-hand corner of the screen, click on the Baselayers menu to select a map view. You can choose: map, satellite, or hybrid view.