sae 1999-01-2583 perance uation of the first ac bipv installation in canada

1、SAE TECHNICAL PAPER SERIESPerformance Evaluation of the First AC BIPV Installation in CanadaLjubisav StamenicBritish Columbia Institute of Technology Eric Smiley, Konrad Colbow and John DeweyJonesSimon Fraser Univ.The 34

2、th Intersociety Energy Conversion Engineering Conference Vancouver, British Columbia August 2-5,1999400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760The appearance of thi

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7、tment.1999-01-2583The Engineering Society For Advancing Mobility Land Sea Air and Space® INTERNATIONAL The Engineering Society For Advancing Mobility Land Sea Air and Space® INTERNATIONALmodules is analyzed

8、, and an increase in array power output of between 0.6% and 3.2% is observed when compared with a DC configured photovoltaic array.INTRODUCTIONBACKGROUND - The performance of Building Integrated Photovoltaic (BIPV

9、) systems is being investigated at the Photovoltaic Energy Applied Research Lab (PEARL) at the British Columbia Institute of Technology (BCIT). A 1 kWp, grid connected array of photovoltaic (PV) modules is integrated

10、 into the South facade of the BCIT Technology Centre building in Burnaby, British Columbia. This is the first grid-connected system in Canada to use AC BIPV modules, an emerging technology in PV applications.The pho

11、tovoltaic system at BCIT is providing experience and research in the design, installation and operation of AC BIPV module technology. AC modules have a small DC to AC grid- connected micro-inverter attached to the back

12、. Power produced by the PV module is converted to utility quality AC electricity at the PV module. In addition, data acquisition functions are integrated directly into the micro-inverter of each module. A remote desk

13、top computer, linked with the inverters, is used to monitor and change the performance parameters of each module, eliminating the need for external instrumentation and simplifying remote diagnosis of problems.AC PV ar

14、rays offer several performance and economic advantages over the standard DC array configurations. Unlike a standard DC array comprised of PV modules connected in series and/or parallel, there are no DC interconnection

15、s between modules. System efficiency is improved since mismatch losses between modules are eliminated and each module can operate at its maximum power point. Installation and design is simplified since DC wiring expe

16、rtise is not required, nor is expensive DC safety equipment.Another advantage of AC modules is individual PV module monitoring. This simplifies diagnosis of problems in the array. Each micro-inverter indicates whether

17、 the PV module to which it is connected is behaving normally, so array diagnostics can be reduced to a simple visual inspection on the monitoring computer. In a DC PV array, particularly a large one, diagnosis of the

18、 array is a major problem due to the need for a large number of electrical measurements to be made directly on the array. AC arrays also have less susceptibility to damage from lighting strikes than DC arrays.BIPV DES

19、IGN ISSUES - The 1 kW AC BIPV array is integrated into the true-South-facing facade of the BCIT Technology Centre building; thus it is oriented vertically. A vertically mounted BIPV array is better suited for winter e

20、nergy production, than summer use. This orientation results in lower annual power output than an optimally oriented array. However it is consistent with the architectural constraints imposed in BIPV systems.While the

21、 losses due to array orientation are unavoidable, grid connected BIPV systems frequently suffer from other reductions in power output. The use of AC BIPV modules at BCIT is an effort to reduce or eliminate those losses

22、. The total power output is reduced when the inverter requires a high power input from the solar array before turning on. [1] Inverters also draw power from the utility grid while they are in stand-by during the nigh

23、t, or when insolation levels are lower than the minimum power required to run the inverter. [2]BIPV arrays often experience shading from nearby buildings or trees, and may comprise PV modules oriented in different dir

24、ections. Both situations reduce system efficiency significantly in a conventionally wired DC array as modules receiving reduced amounts of sunlight will interfere with the performance of other modules connected

25、 in series. Maximum power point tracking (MPPT) of the modules is also compromised under these conditions. [3]SYSTEM OVERVIEWPOWER SYSTEM - The AC BIPV system comprises ten 100-watt Solee S- 100D PV modules to form an

26、 array with a 1 kWp output under standard test conditions (STC). Each module has an OKEfTrace micro-inverter directly connected to the back of the module. Each inverter is rated for 110 W maximum input. It has built

27、-in maximum power point tracking and synchronizes with the grid automatically. Anti- islanding protection for sensing the grid and to protect line workers in the event of power failure, is also built in.The array was

28、installed at the end of 1998. Since that time approximately 180 kWh have been produced. Detailed monitoring started in the spring of 1999.Although the micro-inverters have anti-islanding protection and continuously mo

29、nitor the grid, the utility supplying BCIT (BC Hydro) required the installation of a lockable system isolation switch for this AC BIPV grid- connected system. This switch contains both an automatic low voltage shut-ou

30、t and a manual disconnect switch. In the event of a power failure the system is disconnected from the grid and reconnection is not made until BC Hydro gives permission. To date, no power failure has occurred.MONITORI

31、NG - Monitoring of the BCIT system was undertaken principally for the design and verification of computer modeling tools for BIPV and to evaluate AC module technology. All data is recorded by a desktop computer runnin

32、g proprietary software designed and written by the research team. The data is initially stored on a hard drive and is backed up on CD ROM. Data is recorded at one minute time intervals and averaged to hourly values f

33、or long term storage.The data is collected from two sources. One is the PV array/inverter subsystem, which provides information on performance via an RS-485 port built into the OKE/Trace inverter A separate data acqui

34、sition card collects the meteorological data and temperatures, which is added to the performance data by another software package, also developed specifically for this BIPV system.Solar energy is measured with LI-COR