THERMAL TRACKING FOR SOLAR SYSTEMS

• US 20130081668A1
• Filed: 09/30/2011
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Nextracker
• Original Assignee: Sunpower Corporation (Totalenergies Se)
• Inventors: Linderman, Ryan J.
• Granted Patent: US 8,796,535 B2
• Time in Patent Office: Days
• US Class Current: 136/246
• CPC Class Codes: F24S 50/20 for tracking
• CPC Class Codes: G05D 3/105 Solar tracker
• CPC Class Codes: H01L 31/048 Encapsulation of modules
• CPC Class Codes: H01L 31/0547 comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
• CPC Class Codes: H02S 20/32 specially adapted for solar tracking
• CPC Class Codes: Y02E 10/47 Mountings or tracking
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

A thermal tracking system for a concentrating photovoltaic system is disclosed. The thermal tracking system comprises a photovoltaic receiver. The photovoltaic receiver comprises a photovoltaic laminate and a heat spreader. The thermal tracking system further comprises first and second thermal sensors coupled to the photovoltaic laminate and sensing two temperatures of the laminate. The thermal tracking system also comprises third and fourth thermal sensors positioned adjacent the heat spreader and sensing two temperatures near the heat spreader.

Claims

1. A thermal tracking system for a concentrating photovoltaic system comprising:

a photovoltaic receiver extending in a longitudinal direction, the photovoltaic receiver comprising;

a photovoltaic laminate having a first and second edges extending parallel to the longitudinal direction, the photovoltaic receiver having a front side with a front surface, the front side directed to receive concentrated sunlight and a back side with a back surface, the back side opposite the front side, the photovoltaic laminate comprising a plurality of photovoltaic solar cells;

a heat spreader coupled to the back side of the photovoltaic laminate along the longitudinal direction and extending towards the first and second edges of the photovoltaic laminate, the heat spreader stopping short of the first edge and the second edge;

first and second thermal sensors coupled to the photovoltaic laminate, the first thermal sensor closer to the first edge than the second edge, the second thermal sensor closer to the second edge than the first edge, the first and second thermal sensors adapted to sense a temperature of the photovoltaic laminate; and

third and fourth thermal sensors positioned adjacent the heat spreader, the third thermal sensor positioned between the first edge and the heat spreader, the fourth thermal sensor positioned between the second edge and the heat spreader.

2. The thermal tracking system of claim 1, wherein the first and second thermal sensors are electrically connected.

3. The thermal tracking system of claim 2, wherein the third and fourth thermal sensors are electrically connected.

4. The thermal tracking system of claim 3, wherein the first and second thermal sensors are electrically connected to the third and fourth thermal sensors.

5. The thermal tracking system of claim 4, wherein each of the first, second, third, and fourth thermal sensors are connected in series.

6. The thermal tracking system of claim 1, wherein the third and fourth thermal sensors are spaced apart from the back surface of the photovoltaic laminate.

7. The thermal tracking system of claim 6, wherein the third and fourth thermal sensors are each positioned atop an offset member positioning them apart from the photovoltaic laminate.

8. The thermal tracking system of claim 1, wherein the first thermal sensor is connected in reverse polarity to the second thermal sensor.

9. The thermal tracking system of claim 8, wherein the third thermal sensor is connected in reverse polarity to the fourth thermal sensor.

10. A method for tracking the sun for a concentrated photovoltaic system, the concentrated photovoltaic system comprising a solar receiver comprising a solar laminate and a heat spreader, the method comprising:

sensing a first temperature in a first location of a photovoltaic laminate;

sensing a second temperature in a second location of the photovoltaic laminate;

determining a tracking correction for the concentrated photovoltaic system by comparing the first and second temperatures;

sensing a third temperature in an upstream position of air flowing over the heat spreader;

sensing a fourth temperature in a downstream position of air flowing over the heat spreader; and

adjusting the tracking correction for the concentrated photovoltaic system based on information derived from the third and fourth temperatures.

11. The method of claim 10, wherein comparing the first and second temperatures comprises subtracting a value for the first temperature from a value for the second temperature.

12. The method of claim 10, wherein sensing the third temperature comprises sensing a temperature with a first sensor and sensing the fourth temperature comprises sensing a temperature with a second sensor.

13. The method of claim 10, wherein adjusting the tracking correction based on information derived from the third and fourth temperatures comprises electrically connecting the first sensor and the second sensor.

14. The method of claim 13, wherein electrically connecting the first and second sensors comprises connecting the first and second sensors in reverse polarity.

15. The method of claim 10, wherein adjusting the tracking correction for the concentrated photovoltaic system based on information derived from the third and fourth temperatures comprises adjusting the tracking correction based on cooling of the photovoltaic laminate to improve the estimation of a temperature gradient in the photovoltaic laminate caused by imprecision in positioning of concentrated sunlight on the photovoltaic receiver.

16. The method of claim 10, wherein sensing the first and second temperatures in the first and second locations of the photovoltaic laminate comprises positioning first and second thermocouples against the photovoltaic laminate.

17. The method of claim 10, further comprising adjusting the position of the concentrating photovoltaic system in response to the adjusted tracking correction.

18. A concentrating photovoltaic system comprising:

a reflective surface adapted to concentrate sunlight to produce focused sunlight;

a photovoltaic receiver positioned to receive the focused sunlight, the photovoltaic receiver comprising a photovoltaic laminate comprising photovoltaic solar cells;

first and second thermal sensors positioned contacting the photovoltaic laminate in the concentrating photovoltaic system;

a heat spreader in thermal communication with the photovoltaic laminate, the heat spreader having a first open side and a second open side;

third and fourth thermal sensors, the third thermal sensor positioned near the first open side of the heat spreader and the fourth thermal sensor positioned near the second open side of the heat spreader;

a motor adapted to adjust the position of the concentrating photovoltaic system; and

a control system adapted to operate the motor, the control system connected to and receiving information from the first, second, third, and fourth thermal sensors, the control system further adapted to operate the motor in response to a signal received from at least one of the first, second, third, and fourth thermal sensors.

19. The concentrating photovoltaic system of claim 18, wherein the control system is further adapted to compare information from the first and second thermal sensors to determine a correction value for the position of the concentrating photovoltaic system.

20. The concentrating photovoltaic system of claim 19, wherein the control system is further adapted to adjust the correction value in response to information received from the third and fourth thermal sensors.

21. The concentrating photovoltaic system of claim 20, wherein each of the first, second, third, and fourth thermal sensors are electrically connected to one another.

22. The concentrating photovoltaic system of claim 21, wherein the second thermal sensor is connected in reverse polarity to the first thermal sensor.

23. The concentrating photovoltaic system of claim 22, wherein the fourth thermal sensor is connected in reverse polarity to the third thermal sensor.

24. The concentrating photovoltaic system of claim 18, wherein the photovoltaic solar cells are back-contact solar cells.