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Global Change Master Directory (GCMD)
PVDAQ: Solar Array Efficiency Mapping Tool
Entry ID: NREL_PVDAQ


Summary
Abstract: PVDAQ is a comprehensive mapping tool to help industry and government planners study solar array efficiency. The PV Data Acquisition (PVDAQ) application is designed to provide access to PV system performance data collected by NREL from systems all over the country. 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 publicly 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:

1) 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)

2) 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)


3) 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


4) 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


5) 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%.

Related URL
Link: GOTO WEB TOOL > MAP VIEWER

ISO Topic Category
ECONOMY
UTILITIES/COMMUNICATIONS
STRUCTURE


Personnel
NATIONAL RENEWABLE ENERGY LABORATORY
Role: TECHNICAL CONTACT
Phone: 202-488-2200
Contact Address:
901 D. Street, S.W. Suite 930
Province or State: Washington, D.C.
Postal Code: 20024-2157
Country: USA


Extended Metadata Properties
(Click to view more)

Creation and Review Dates
SERF Creation Date: 2014-06-06
SERF Last Revision Date: 2018-08-07



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