panel 39 heating the oil in panel 39 and then returning the oil to tank 37 complete demulsification of the oil in tank 37 depends mainly on the amount of heat added by the panel 39 and the retention time of the oil in tank 37 an advantage of this method is that the heat from panel 39 is accumulated in the oil retained in tank 37 in this manner a demulsification over a period of time can occur the periods of solar heating causing the temperature of the oil to increase until completion of demulsification is achieved this allows the intermittent heat of the sun to be used to advantage for demulsification if desired pump 39 can be made responsive to the temperature of solar panel 39 such that pumping occurs only when heating of the oil will occur this prevents unnecessary circulation of the oil a conventional thermostat located on panel 39 can be used and connected to operate pump 47 this is represented schematically in fig2 by dotted line 48 if unsalable gas is available or solar heat is not sufficient to provide demulsification it is useful to combine the concepts of this invention with a conventional tower demulsifier fig3 shows a conventional tower demulsifier 49 coupled with solar panel 51 details of the operation of conventional tower demulsifiers are described in u s pat nos 3 029.