Menke Projects

All of the solar water heating schemes (shown below) prior to Feb. 2022 have been abandoned in favor of PV direct to the water heater resistive element.  The element in the tank measures 12.5 ohms, and it does not care if it is hooked to 240 volts ac, or the dc voltage coming from the solar panels. The label on the solar panel shows open circuit voltage and short circuit current.  I connected a string of three 240 watt solar panels to the lower element of a 50 gallon forty year old water heater tank.  Using the label data of Power max. voltage and current, the source impedance of the panels is either 4.44 ohms or 3.85 ohms, and three in series would be a current source with an impedance of either 13.3 or 11.6 ohms. The 4500 watt 240 volt resistance heater measures 12.5 ohms. For maximum power transfer, my source impedance of 13.3 or 11.6 is close to the load resistance of 12.5.  Unfortunately, this is for best solar conditions around solar noon, when I can measure 80 vol