Optically-controlled shunt circuit for maximizing photovoltaic panel efficiency

• US 8,686,332 B2
• Filed: 03/07/2011
• Issued: 04/01/2014
• Est. Priority Date: 03/07/2011
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Razouk, Reda R., Hopper, Peter J.
• Primary Examiner(s): LUU, THANH X
• Application Number:
  US13/042,173
• Publication Number:
  US 20120228480A1
• Time in Patent Office: 1,121 Days
• Field of Search: 250/203.4, 136/244
• US Class Current: 250/203.4
• 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: H03K 17/78 using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

An optically-controlled shunt (OCS) circuit includes a switch and a light sampler. The light sampler is coupled to the switch and is configured to sample light at a photovoltaic (PV) cell corresponding to the OCS circuit and to turn on the switch when the sampled light comprises insufficient light for the PV cell. The light sampler may also be configured to turn off the switch when the sampled light comprises sufficient light for the PV cell. The light sampler may further be configured to partially turn on the switch when the sampled light comprises adequate light for the PV cell and to turn off the switch when the sampled light comprises full light for the PV cell. The switch could include a transistor, and the light sampler could include a photodiode.

Claims

1. An optically-controlled shunt (OCS) circuit for a photovoltaic cell, comprising:

a switch; and

a light sampler coupled to the switch, the light sampler configured to sample light at the photovoltaic (PV) cell and to turn on the switch when the sampled light comprises insufficient light for the PV cell, to partially turn on the switch when the sampled light comprises adequate light for the PV cell, and to turn off the switch when the sampled light comprises full light for the PV cell.

2. The OCS circuit of claim 1, wherein the switch comprises a transistor.

3. The OCS circuit of claim 1, wherein the light sampler comprises a photodiode.

4. The OCS circuit of claim 1, further comprising a nonlinear amplifier coupled between the light sampler and the switch;

wherein the light sampler is configured to generate an activation signal based on the sampled light;

wherein the non-linear amplifier is configured to non-linearly amplify the activation signal to generate a switch signal; and

wherein the switch is configured to be partially turned on based on the switch signal.

5. The OCS circuit of claim 1, wherein:

the switch comprises a PMOS transistor;

the light sampler comprises a photodiode and a biasing resistor;

a first node of the PV cell is coupled to a drain of the PMOS transistor and to a first node of the biasing resistor;

a second node of the PV cell is coupled to a source of the PMOS transistor and to a first node of the photodiode; and

a gate of the PMOS transistor is coupled to a second node of the biasing resistor and a second node of the photodiode.

6. A bypassable photovoltaic cell, comprising:

a photovoltaic (PV) cell; and

an optically-controlled shunt (OCS) circuit coupled to the PV cell, the OCS circuit including

a switch;

a light sampler coupled to the switch;

the OCS circuit configured to turn on the switch to bypass the PV cell when insufficient light is available for the PV cell, to partially turn on the switch when the sampled light comprises adequate light for the PV cell, and to turn off the switch when the sampled light comprises full light for the PV cell.

7. The bypassable cell of claim 6, wherein the switch comprises a transistor.

8. The bypassable cell of claim 6, wherein the light sampler comprises a photodiode.

9. The bypassable cell of claim 6, wherein:

the OCS circuit further comprises a non-linear amplifier coupled between the light sampler and the switch;

the light sampler is configured to generate an activation signal based on the sampled light;

the non-linear amplifier is configured to non-linearly amplify the activation signal to generate a switch signal; and

the switch is configured to be partially turned on based on the switch signal.

10. The bypassable cell of claim 6, wherein:

the switch comprises a PMOS transistor;

the light sampler comprises a photodiode and a biasing resistor;

a first node of the PV cell is coupled to a drain of the PMOS transistor and to a first node of the biasing resistor;

a second node of the PV cell is coupled to a source of the PMOS transistor and to a first node of the photodiode; and

a gate of the PMOS transistor is coupled to a second node of the biasing resistor and a second node of the photodiode.

11. A method for bypassing a photovoltaic (PV) cell, comprising:

sampling light corresponding to the PV cell; and

bypassing the PV cell using an optically controlled shunt (OCS) circuit, including

activating the OCS circuit when the sampled light comprises insufficient light for the PV cell to bypass the PV cell;

partially activating the OCS circuit when the sampled light comprises adequate light for the PV cell; and

deactivating the OCS circuit when the sampled light comprises full light for the PV cell.

12. The method of claim 11, wherein partially activating the OCS circuit comprises:

generating an activation signal based on the sampled light;

non-linearly amplifying the activation signal to generate a switch signal; and

partially bypassing the PV cell based on the switch signal.