Detecting and reporting faults in solar thermal systems

Abstract

A control system and a method are disclosed for detecting and reporting a variety of faults in solar thermal systems. Detected and reported faults include a low fluid condition in a closed loop of a solar thermal system in a drain-back configuration, a pressure drop in a closed of a solar thermal system in a glycol configuration, a pressure drop in a potable water portion of a solar thermal system of either configuration. Additionally, systems and methods are disclosed for detecting and reporting power outages and heat exchanger scaling, both of which may be experienced by a solar thermal system.

1 . A system for controlling the operation of a solar thermal system in a drain-back configuration, the system comprising:
 a fluid level switch positioned to sense a fluid level within a closed loop of the system;   a pressure transducer positioned to sense a pressure drop within the system; and   a controller coupled to the fluid level switch and the pressure transducer and a network.   
   
   
       2 . The system of  claim 1 , wherein the controller is configured to:
 turn off a pump within the closed loop and transmit an alert over the network in response to the fluid level switch indicating the fluid level being below a threshold.   
   
   
       3 . The system of  claim 1 , wherein the controller is configured to:
 responsive to the pressure transducer indicating a pressure drop, turn off a pump within the system and transmit an alert over the network.   
   
   
       4 . A system for controlling the operation of a solar thermal system in a drain-back configuration, the system comprising:
 a drain-back tank;   a fluid level switch positioned within the drain-back tank to sense a fluid level within a closed loop of the system;   a controller coupled to the fluid level switch and a network, the controller configured to turn off a pump within the closed loop and transmit an alert over the network in response to the fluid level switch indicating the fluid level being below a threshold.   
   
   
       5 . A system for controlling the operation of a solar thermal system in a drain-back configuration, the system comprising:
 a pressure transducer positioned to sense a pressure drop within the system;   a controller coupled to the pressure transducer and a network, the controller configured to, responsive to the pressure transducer indicating a pressure drop, turn off a pump within the system and transmit an alert over the network.   
   
   
       6 . A system for controlling the operation of a solar thermal system in a glycol configuration, the system comprising:
 a first pressure transducer positioned to sense a pressure drop within a potable water portion of the system;   a second pressure transducer positioned to sense a pressure drop within a closed loop of the system;   a first temperature sensor positioned to sense a first temperature at a first location;   a second temperature sensor positioned to sense a second temperature at a second location;   a flowmeter positioned to sense a flow rate; and   a controller coupled to the first pressure transducer and the second pressure transducer and the first temperature sensor and the second temperature sensor and the flowmeter and a network.   
   
   
       7 . The system of  claim 6 , wherein the controller is configured to:
 responsive to the first pressure transducer indicating a pressure drop:
 turn off a first pump in the potable water portion; 
 transmit an alert over the network; 
 determine a risk of a glycol fluid within the closed loop overheating; 
 calculate a delay based on the risk; and 
 turn off a second pump in the closed loop after the delay. 
   
   
   
       8 . The system of  claim 6 , wherein the controller is configured to:
 detect a restart of the system;   determine a duration that the system was without power;   determine a risk of a glycol fluid overheating during the duration; and   responsive to determining the risk as above a threshold, transmit an alert over the network.   
   
   
       9 . The system of  claim 6 , further comprising a heat exchanger, wherein the controller is configured to report scaling in the heat exchanger. 
   
   
       10 . A system for controlling the operation of a solar thermal system in a glycol configuration, the system comprising:
 a first pressure transducer positioned to sense a pressure drop within a potable water portion of the system, the first pressure transducer coupled to a controller;   a second pressure transducer positioned to sense a pressure drop within a closed loop of the system, the second pressure transducer coupled to the controller;   the controller coupled to a network and configured to, responsive to the first pressure transducer indicating a pressure drop:
 turn off a first pump in the potable water portion; 
 transmit an alert over the network; 
 determine a risk of a glycol fluid within the closed loop overheating; 
 calculate a delay based on the risk; and 
 turn off a second pump in the closed loop after the delay. 
   
   
   
       11 . The system of  claim 10 , wherein determining the risk of the glycol fluid overheating comprises:
 analyzing data related to one or more environmental conditions of the solar thermal system; and   determining a likelihood that a temperature of the glycol fluid will exceed a threshold.   
   
   
       12 . The system of  claim 10 , the controller further configured to, responsive to the second pressure transducer indicating a pressure drop:
 turn off all pumps within the system; and   transmit an alert over the network.   
   
   
       13 . A system for controlling the operation of a solar thermal system in a glycol configuration, the system comprising a controller coupled to a network, the controller configured to:
 detect a restart of the system;   determine a duration that the system was without power;   determine a risk of a glycol fluid overheating during the duration; and   responsive to determining the risk as above a threshold, transmit an alert over the network.   
   
   
       14 . The system of  claim 13 , wherein determining the risk of the glycol fluid overheating during the duration comprises:
 analyzing data related to one or more environmental conditions of the system during the duration.   
   
   
       15 . The system of  claim 14 , wherein determining the risk of the glycol fluid overheating during the duration further comprises:
 analyzing data related to one or more prior system events; and   responsive to determining the risk as below a threshold, storing data related to the duration as a system event.   
   
   
       16 . A system for reporting scaling in a heat exchanger of a solar thermal system, the system comprising a controller coupled to a network and configured to:
 calculate a present solar thermal output for the system;   compare the present solar thermal output to a previously calculated solar thermal output; and   responsive to the difference between the present solar thermal output and the previously calculated solar thermal output exceeding a threshold, transmit an alert over the network.   
   
   
       17 . The system of  claim 16 , further comprising:
 a first temperature sensor positioned to sense a first temperature at a first location, the first temperature sensor coupled to a controller;   a second temperature sensor positioned to sense a second temperature at a second location, the second temperature sensor coupled to the controller;   a flowmeter positioned to sense a flow rate; and   wherein calculating a solar thermal output for the system comprises calculating a difference between the first temperature and the second temperature and multiplying the difference by a flow rate.   
   
   
       18 . A method for controlling the operation of a solar thermal system in a drain-back configuration, the method comprising:
 responsive to detecting that a fluid level within a closed loop of the system is below a threshold, turning off a pump within the closed loop; and   transmitting an alert.   
   
   
       19 . A method for controlling the operation of a solar thermal system in a drain-back configuration, the method comprising:
 responsive to detecting a pressure drop within the system, turning off a pump within the system; and   transmitting an alert.   
   
   
       20 . A method for controlling the operation of a solar thermal system in a glycol configuration, the method comprising:
 responsive to detecting a pressure drop within the system, determining a location of the pressure drop;   responsive to determining the location as within a potable water portion of the system:
 turning off a first pump in the potable water portion; 
 transmitting an alert; 
 determining a risk of a glycol fluid within a closed loop overheating; 
 calculating a delay based on the risk; and 
 turning off a second pump in the closed loop after the delay. 
   
   
   
       21 . The method of  claim 20 , wherein determining the risk of the glycol fluid overheating comprises:
 analyzing data related to one or more environmental conditions of the solar thermal system; and   determining a likelihood that a temperature of the glycol fluid will exceed a threshold.   
   
   
       22 . The method of  claim 20 , further comprising, responsive to determining the location as within the closed loop:
 turning off all pumps within the system; and   transmitting an alert over the network.   
   
   
       23 . A method for controlling the operation of a solar thermal system in a glycol configuration, the method comprising:
 responsive to detecting a restart of the system:
 determining a duration that the system was without power; 
 determining a risk of a glycol fluid overheating during the duration; and 
 responsive to determining the risk as above a threshold, transmitting an alert. 
   
   
   
       24 . The method of  claim 23 , wherein determining the risk of the glycol fluid overheating during the duration comprises:
 analyzing data related to one or more environmental conditions of the system during the duration.   
   
   
       25 . The method of  claim 24 , wherein determining the risk of the glycol fluid overheating during the duration further comprises:
 analyzing data related to one or more prior system events; and   responsive to determining the risk as below a threshold, storing data related to the duration as a system event.   
   
   
       26 . A method for reporting scaling in a heat exchanger of a solar thermal system, the method comprising:
 calculating a present solar thermal output for the system;   comparing the present solar thermal output to a previously calculated solar thermal output; and   responsive to the difference between the present solar thermal output and the previously calculated solar thermal output exceeding a threshold, transmitting an alert.   
   
   
       27 . The method of  claim 26 , wherein calculating a solar thermal output for the system comprises:
 calculating a difference between a first temperature at a first location and a second temperature at a second location; and   multiplying the difference by a flow rate.