Solar tracker stow system and method

Abstract

A solar tracker system having one or more solar trackers that each include one or more panels and one or more actuators coupled to the one or more panels, the one or more actuators having a first and second vessel; and an electronic control unit configured to inflate the first vessel with fluid from a fluid source and configured to separately inflate the second vessel with fluid from the fluid source. The electronic control unit is configured to determine that a stow event is present based on a first set of environmental data obtained from an environmental sensor that indicates environmental conditions pose a threat to the one or more solar trackers, and in response to determining that the stow event is present, actuate the one or more panels toward a stow configuration target angle by at least inflating the first or second vessels with fluid from the fluid source.

What is claimed is: 
     
         1 . A solar tracker system comprising:
 a plurality of solar trackers, with each solar tracker including:
 a plurality of photovoltaic cells disposed in a common plane and extending along a first length having a first axis, the plurality of photovoltaic cells coupled to rails that extend along a second axis that is parallel to the first axis; 
 a plurality of actuators coupled to the rails and configured to collectively rotate the plurality of photovoltaic cells, the plurality of actuators disposed along a common third axis that is parallel to the first and second axis, each of the plurality of actuators having:
 a bottom plate; 
 a top plate coupled to the rails; and 
 a first and second bellows extending between and coupled to the top plate and bottom plate; 
 
   a wind sensor;   a row controller operably coupled to and configured to control the plurality of solar trackers, the row controller comprising:
 a shared pneumatic fluid source; and 
 a pneumatic circuit having one or more pneumatic lines coupled of a first set of bellows including the first bellows of the plurality of actuators and one or more pneumatic lines coupled of a second set of bellows including the second bellows of the plurality of actuators, the first and second sets of bellows being mutually exclusive; and 
   an active electronic pneumatic control unit configured to collectively inflate the first set of bellows with fluid from the shared pneumatic fluid source via the pneumatic circuit and configured to separately inflate the second set of bellows with fluid from the shared pneumatic fluid source via the pneumatic circuit, the active electronic pneumatic control unit configured for:
 actuating the plurality of photovoltaic cells toward a first determined target ideal angle by at least inflating the first or second set of bellows with fluid from the shared pneumatic fluid source via the pneumatic circuit, the actuating based at least in part on determining that a determined difference between a first determined current angle of the plurality of photovoltaic cells and the first determined target ideal angle of the plurality of photovoltaic cells is outside of a tolerance range, 
 determining that a stow event is present based at least in part on a first set of wind velocity data obtained from the wind sensor including wind velocity data above a defined threshold and for a defined time period that indicates wind conditions being present that pose a threat to at least one of the plurality of solar trackers, the threat to at least one of the plurality of solar trackers including the wind conditions potentially causing physical damage to the at least one of the plurality of solar trackers, 
 in response to determining that the stow event is present, actuating the plurality of photovoltaic cells toward a stow configuration target angle by at least inflating the first or second set of bellows with fluid from the shared pneumatic fluid source via the pneumatic circuit, 
 upon reaching the stow configuration target angle, inflating the first and second set of bellows to an equilibrium to rigidly fix the plurality of photovoltaic cells at the stow configuration target angle, 
 while the plurality of photovoltaic cells are rigidly fixed at the stow configuration target angle, determining that the stow event is no longer present based at least in part on a second set of wind velocity data obtained from the wind sensor including wind velocity data below a defined threshold and for a defined time period that indicates wind conditions being present that no longer pose the threat to the plurality of solar trackers, and 
 in response to determining that the stow event is no longer present, actuating the plurality of photovoltaic cells toward a second determined target ideal angle by at least inflating the first or second set of bellows with fluid from the shared pneumatic fluid source via the pneumatic circuit, the actuating based at least in part on determining that a determined difference between a second determined current angle of the plurality of photovoltaic cells and the second determined target ideal angle of the plurality of photovoltaic cells is outside of the tolerance range. 
   
     
     
         2 . The solar tracker system of  claim 1 , further comprising determining that a stow event is present based at least in part on one or more of:
 a detected power loss;   a detected failure of pneumatic elements;   a detected failure of one or more sensors; and   a detected failure of a control system.   
     
     
         3 . The solar tracker system of  claim 1 , wherein the stow configuration target angle is an angle of the plurality of photovoltaic cells between two maximum tilt position angles where the plurality of solar trackers are forced against a respective hard stop at the maximum tilt position angles. 
     
     
         4 . The solar tracker system of  claim 1 , wherein the active electronic pneumatic control unit is configured to operate the plurality of actuators at a minimum operating pressure when no wind is present and configured to dynamically increase stiffness of the plurality of actuators in response to increasing wind speed by dynamically increasing operating pressure of the plurality of actuators. 
     
     
         5 . A solar tracker system comprising:
 a plurality of solar trackers, with each solar tracker including one or more solar panels and a plurality of actuators coupled to the one or more solar panels, each of the plurality of actuators having first and second elastic vessels;   a wind sensor; and   an electronic control unit configured to collectively inflate a first set of the first elastic vessels with fluid from a fluid source and configured to separately inflate a second set of the second elastic vessels with fluid from the fluid source, the electronic control unit configured to:
 determine that a stow event is present based at least in part on a first set of wind speed data obtained from the wind sensor that indicates wind conditions being present that pose a threat to at least one of the plurality of solar trackers, the threat to at least one of the plurality of solar trackers including the wind conditions potentially causing physical damage to the at least one of the plurality of solar trackers, 
 in response to determining that the stow event is present, actuate the one or more solar panels toward a stow configuration target angle by at least inflating the first or second set of elastic vessels with fluid from the fluid source, and 
 upon reaching the stow configuration target angle, inflate the first and second set of elastic vessels to rigidly fix the one or more solar panels at the stow configuration target angle. 
   
     
     
         6 . The solar tracker system of  claim 5 , wherein the determining that a stow event is present based at least in part on the first set of wind speed data obtained from the wind sensor that indicates wind conditions being present that pose the threat to at least one of the plurality of solar trackers includes determining that the first set of wind speed data indicates wind speed above a defined wind speed threshold and for a defined time period. 
     
     
         7 . The solar tracker system of  claim 5 , wherein the electronic control unit is further configured to:
 while the one or more solar panels are fixed at the stow configuration target angle, determining that the stow event is no longer present based at least in part on a second set of wind speed data obtained from the wind sensor including wind speed data below a defined threshold and for a defined time period that indicates wind conditions being present that no longer pose the threat to the plurality of solar trackers.   
     
     
         8 . The solar tracker system of  claim 7 , wherein the electronic control unit is further configured to:
 in response to determining that the stow event is no longer present, actuating the one or more solar panels toward a determined target ideal angle by at least deflating or inflating the first or second set of elastic vessels with fluid from the fluid source, the actuating based at least in part on determining that a determined difference between a determined current angle of the one or more solar panels and the determined target ideal angle of the one or more solar panels is outside of a tolerance range.   
     
     
         9 . The solar tracker system of  claim 5 , wherein the electronic control unit is further configured to:
 determine that an alert should be sent to a user regarding wind conditions based at least in part on determining that a first set of wind speed data indicates wind speed above a defined wind speed threshold and for a defined time period; and   send an alert to the user regarding wind speed proximate to the solar tracker system potentially causing physical damage to the at least one of the plurality of solar trackers.   
     
     
         10 . A solar tracker system comprising:
 one or more solar trackers, with each solar tracker including one or more panels and one or more actuators coupled to the one or more panels, each of the one or more actuators having a first vessel and a second vessel; and   an electronic control unit configured to inflate the first vessel with fluid from a fluid source and configured to separately inflate the second vessel with fluid from the fluid source, the electronic control unit configured to:
 determine that a stow event is present based at least in part on a first set of environmental data obtained from an environmental sensor that indicates environmental conditions being present that pose a threat to the one or more solar trackers, and 
 in response to determining that the stow event is present, actuate the one or more panels toward a stow configuration target angle by at least inflating the first or second vessels with fluid from the fluid source. 
   
     
     
         11 . The solar tracker system of  claim 10 , wherein the electronic control unit is further configured to:
 upon reaching the stow configuration target angle, inflate the first and second vessels to fix the one or more panels at the stow configuration target angle.   
     
     
         12 . The solar tracker system of  claim 10 , wherein the threat to the at least one of the one or more solar trackers including the environmental conditions potentially causing physical damage to the one or more solar trackers. 
     
     
         13 . The solar tracker system of  claim 10 , wherein the environmental sensor comprises a wind sensor. 
     
     
         14 . The solar tracker system of  claim 10 , wherein first set of environmental data comprises wind speed data or wind velocity data. 
     
     
         15 . The solar tracker system of  claim 10 , wherein the determining that the stow event is present is based at least in part on a first set of wind speed data obtained from a wind sensor that indicates wind conditions being present that pose the threat to the one or more solar trackers, and wherein determining that the stow event is present further includes determining that the first set of wind speed data indicates wind speed above a defined wind speed threshold. 
     
     
         16 . The solar tracker system of  claim 10 , wherein the electronic control unit is further configured to:
 while the one or more panels are fixed at the stow configuration target angle, determining that the stow event is no longer present based at least in part on a second set of environmental data obtained from the environmental sensor; and   in response to determining that the stow event is no longer present, actuating the one or more panels toward a determined target ideal angle by at least deflating or inflating the first or second vessel, the actuating based at least in part on determining that a determined difference between a determined current angle of the one or more panels and the determined target ideal angle of the one or more panels is outside of a tolerance range.   
     
     
         17 . The solar tracker system of  claim 10 , further comprising determining that a stow event is present based at least in part on one or more of:
 a detected power loss;   a detected failure of a pneumatic element;   a detected failure of one or more sensors; and   a detected failure of a control system.   
     
     
         18 . The solar tracker system of  claim 10 , wherein the stow configuration target angle is an angle of the one or more panels between two maximum tilt position angles where the one or more solar trackers are forced against a respective hard stop at the maximum tilt position angles. 
     
     
         19 . The solar tracker system of  claim 10 , wherein the electronic control unit is configured to operate the one or more actuators at a minimum operating pressure when no wind is present and configured to dynamically increase stiffness of the one or more actuators in response to increasing wind speed by dynamically increasing operating pressure of the one or more actuators. 
     
     
         20 . The solar tracker system of  claim 10 , wherein the electronic control unit is further configured to:
 determine that an alert should be sent to a user regarding environmental conditions based at least in part on a second set of data from the environmental sensor; and   send an alert to the user regarding environmental conditions proximate to the solar tracker system potentially causing physical damage to the one or more solar trackers.