Solar energy water heating system

Abstract

In one aspect, the invention is directed to a solar energy water heating system for heating water in a water storage tank. In one particular embodiment, the system includes a controller, a solar energy collector whose energy contribution to water in the tank is controlled by the controller, and a non-solar heating system that is not controlled by the controller. Water in the tank may be heated by one or both of the non-solar heating system and energy from the solar energy collector. The controller can determine the amount of energy contributed by solar energy to the water in the tank. In another embodiment, the solar energy water heating system incorporates a controller that controls both the operation of the pump and the operation of the non-solar heating system. In another embodiment, a network of solar energy water heating systems is provided.

1 . A solar energy water heating system, comprising:
 a water storage tank;   a non-solar heating system configured to heat water in the water storage tank;   a thermostat positioned to sense the temperature indicative of the temperature of water in the water storage tank, wherein the thermostat is operatively connected to the non-solar heating system;   a solar energy collector;   a heat exchanger;   a first fluid circuit between the solar energy collector and the heat exchanger;   a pump configured to pump fluid through the first fluid circuit;   a second fluid circuit between the water storage tank and the heat exchanger, wherein the heat exchanger is configured to transfer heat from fluid in the first fluid circuit to water in the second fluid circuit, wherein the second fluid circuit is fluidically connectable to a water source; and   a controller configured to control the operation of the pump, wherein the controller is further configured to receive non-solar heating system state signals indicative of whether the non-solar heating system is on and wherein the controller is configured to determine the amount of energy transferred from the solar energy collector to water in the water storage tank based at least in part on the non-solar heating system state signals.   
   
   
       2 . A solar energy water heating system as claimed in  claim 1 , wherein the controller is further configured to determine the amount of energy transferred from the solar energy collector to water in the water storage tank based on the temperature of water in the water storage tank, on the flow rate and temperature of any water introduced to the second fluid circuit from the water source, and on a determination of the amount of energy introduced to the water in the storage tank by the non-solar heating system. 
   
   
       3 . A solar energy water heating system as claimed in  claim 2 , wherein the controller is further configured to determine the amount of energy introduced to the water in the storage tank by the non-solar heating system based on the amount of time the non-solar heating system is on and on the power of the non-solar heating system. 
   
   
       4 . A solar energy water heating system as claimed in  claim 2 , further comprising a storage tank water temperature sensor, wherein the controller is further configured to receive from the storage tank water temperature sensor signals indicative of the temperature of water in the water storage tank, and wherein the controller is further configured to determine the amount of energy transferred from the solar energy collector to water in the water storage tank based in part on the temperature of water in the water storage tank. 
   
   
       5 . A solar energy water heating system as claimed in  claim 4 , wherein the water storage tank has a consumption outlet and wherein the storage tank water temperature sensor is positioned downstream from the consumption outlet. 
   
   
       6 . A solar energy water heating system as claimed in  claim 2 , further comprising a source water temperature sensor, wherein the controller is further configured to receive signals from the source water temperature sensor indicative of the temperature of water from the water source. 
   
   
       7 . A solar energy water heating system as claimed in  claim 2 , further comprising a flow meter, wherein the controller is configured to receive flow meter signals from the flow meter indicative of the flow rate of water into the second fluid circuit from the water source. 
   
   
       8 . A solar energy water heating system as claimed in  claim 1 , wherein the controller includes a display and is configured to output on the display a value indicative of the amount of energy saved by heating water from the water storage tank with energy from the solar energy collector. 
   
   
       9 . A solar energy water heating system, comprising:
 a water storage tank having a consumption outlet;   a non-solar heating system configured to heat water in the water storage tank;   a solar energy collector;   a heat exchanger;   a first fluid circuit between the solar energy collector and the heat exchanger;   a pump configured to pump fluid through the first fluid circuit;   a second fluid circuit between the water storage tank and the heat exchanger, wherein the heat exchanger is configured to transfer heat from fluid in the first fluid circuit to water in the second fluid circuit, wherein the second fluid circuit is fluidically connectable to a water source;   a storage tank water temperature sensor positioned downstream from the consumption outlet; and   a controller configured to receive signals from the storage tank water temperature sensor indicative of the temperature of water leaving the water storage tank, wherein the controller is configured to prevent operation of the pump if the signals from the storage tank water temperature sensor indicate the temperature of water in the water storage tank exceeds a predetermined high storage tank water temperature.   
   
   
       10 . A solar energy water heating system as claimed in  claim 9 , wherein the predetermined high storage tank water temperature is about 85 degrees Celsius. 
   
   
       11 . A solar energy water heating system, comprising:
 a water storage tank;   a solar energy collector;   a heat exchanger;   a first fluid circuit between the solar energy collector and the heat exchanger;   a pump configured to pump fluid through the first fluid circuit;   a second fluid circuit between the water storage tank and the heat exchanger, wherein the heat exchanger is configured to transfer heat from fluid in the first fluid circuit to water in the second fluid circuit, wherein the second fluid circuit is fluidically connectable to a water source;   a solar energy collector temperature sensor positioned to sense temperature indicative of the temperature of the solar energy collector;   a source water temperature sensor positioned to sense temperature indicative of the temperature of water from the water source; and   a controller configured to receive solar energy collector temperature sensor signals from the solar energy collector temperature sensor and source water temperature sensor signals from the source water temperature sensor, wherein the controller is configured to prevent operation of the pump if either the solar energy collector temperature sensor signals indicate a solar energy collector temperature that is below a predetermined low solar energy collector temperature or if the source water temperature sensor signals indicate a source water temperature that is below a predetermined low source water temperature.   
   
   
       12 . A solar energy water heating system as claimed in  claim 11 , wherein the predetermined low solar energy collector temperature is about 4 degrees Celsius and wherein the predetermined low source water temperature is about 4 degrees Celsius. 
   
   
       13 . A solar energy water heating system as claimed in  claim 12 , wherein the first fluid circuit contains a fluid that is a mixture of propylene glycol and water.