The SunCell® was submersed in an 850-liter deionized water tank that was initially at room temperature. The SunCell® molten gallium internal temperature remained steady at about 500°C which is a typical operating temperature of a steam turbine power plant. A manifold of water jets maintained a stable external cell temperature while avoidance of localized hot spot formation on the walls was solved using a ceramic liner. The run duration was extended to twenty-four hours while avoiding the limiting thermal tolerance of the water tank by exchanging hot water with cold water from another tank. The SunCell® engineering issues are largely solved towards the goal of a commercial heater of several hundred kilowatts to service the greater than $8T/y thermal market.