Photovoltaic array systems, methods, and devices with bidirectional converter

• US 8,471,408 B2
• Filed: 12/05/2012
• Issued: 06/25/2013
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: CE+T Group SA
• Original Assignee: Ideal Power Converters, Inc.
• Inventors: Bundschuh, Paul, Alexander, William C.
• Primary Examiner(s): Fleming, Fritz M
• Application Number:
  US13/705,240
• Publication Number:
  US 20130114303A1
• Time in Patent Office: 202 Days
• Field of Search: 307/64, 307/80, 307/85, 307/151
• US Class Current: 307/80
• CPC Class Codes: G01R 31/2603 for curve tracing of semiconductor characteristics, e.g. on oscilloscope
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02M 7/66 with possibility of reversal
• CPC Class Codes: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: H02S 50/10 Testing of PV devices, e.g. of PV modules or single PV cells testing of semiconductor devices during manufacturing H01L22/00
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

Devices, systems and methods for operating, monitoring and diagnosing photovoltaic arrays used for solar energy collection. The system preferably includes capabilities for monitoring or diagnosing an array, under some circumstances, by using a bidirectional power converter not only to convert the DC output of the array to output power under some conditions, but also, for diagnostic operations, applying a back-converted DC voltage to the array.

Claims

1. A method for operating a photovoltaic array comprising:

in a first mode, providing DC current from photovoltaic cells, with a first voltage polarity, to a bidirectional power converter, and operating said bidirectional power converter to provide an AC power output onto an AC connection;

in a second mode, operating said bidirectional converter in reverse, to apply a DC potential to the string of photovoltaic cells, with a voltage polarity which is opposite to said first voltage polarity; and

varying said DC potential, while measuring electric current through said string of photovoltaic cells, to thereby obtain an I-V profile; and

using said I-V profile to evaluate the string of photovoltaic cells.

2. The method of claim 1, wherein, in said second mode, said bidirectional converter is powered from said AC connection.

3. The method of claim 1, wherein said second mode is initiated automatically, from time to time, during normal operation.

4. The method of claim 1, wherein said second mode is initiated automatically, from time to time, during dark conditions.