Hot-Control Smart Controller for Residential Solar Water-Heater


Traditional solar water heater system functions on the basic physics phenomena indicating that  hot water has lower specific gravity and therefore floats on top of the cold water, forcing to install the hot water reservoir/boiler higher than the solar panel that absorbs the solar energy to heat the water. The entire cold water content is  to circulate slowly (in closed circuit) through the water  reservoir  until the entire water content heats up. The process takes about two hours per 10 degrees of temperature increase in a hot and sunny day.


The Hot-Control ™   smart system utilizes a small, electric pump combined with an advanced control scheme to optimize system performance with the following excellent results:


  1. The hot water reservoir can be located anywhere!, breaking the above mentioned restriction of must install on top of the solar panel, resulting reduced exposure to adverse climate conditions on the roof. Additionally the possibility to conceal the reservoir contributes to architecture, aesthetics and is environmentally friendly.


  1. Now it is possible to locate the reservoir closer to where the hot water is needed, reducing wasted heat and water compared to longer connecting pipes.


  1. Hot-Control ™   Fuzzy Logic design calculates the amount of water to transfer from Solar Panels  to the reservoir delivering only hot water to the top of reservoir.


  1. With Hot-Control ™   very fast accumulation of hot water is possible even when the sun shines during limited periods. The system assures there is always a sufficient quantity of hot water at the top of the reservoir for immediate use (even during relatively cloudy days).


  1. Wide diagnostic capabilities are included with indications on freezing conditions, electrical wire disconnection, no water situation, clogged water pipes and overheat alarm, all displayed on a led indicator panel.


  1. During any malfunction Hot-Control ™ will bypass the problem by activating alternative “emergency program” until the problem is fixed.



Principle of Operation


Special Temperature sensor  is installed in the water reservoir, monitoring the water temperature. Hot-Control ™ controller is activating a small electrical water pump accordingly to transfer already hot water from the solar panel into the reservoir, avoiding the transfer of cold water into it! Additionally, system integrity is continuously monitored.

Normal Controlled range is 28 to 96 degrees centigrade. Extended working range of 20 to 150 allows emergency programs activation in case of malfunction. 




Easy and simple installation by solar water heater installation technician. No special skills are required. The technician has at his disposal three maintenance programs to assist him in installation and troubleshooting.  Everyday operation is absolutely automatic.


Various System Configurations


1.      Basic Hot-Control ™ system with one solar panel and one hot water reservoir.

2.      Multi Hot-Control ™ system for a cluster of solar panels.

3.      Split Hot-Control ™ system with Master / Slave configuration. Master unit located close to Solar Panel/s and  the slave units close to each hot water reservoir supervising on hot water intake needed  for each reservoir (additionally eliminates the need for an expensive internal heat exchanger).



 Versatile system intended for broad heating system configurations, from basic systems with only one solar panel and one reservoir up to a solar panel cluster capable of high capacity heating including heated swimming pools.


The innovative Hot-Control ™ approach was developed  three years ago and implemented in new and advanced electronic control circuits. Satisfied customer base of more than 3500 installations approves day after day the necessity of Hot-Control ™ system to a truly successful solar water heating system. The flexibility of the system and its computerized control makes it an ideal solution for extremely cold or extremely hot climatic conditions. System  parameters can be customized and fine tuned for specific design requirements.