The aim of this thesis is to improve PV-RO water treatment system that consists of solar panels, a pump and a RO membrane. The first part of the thesis is focused on defining the ideal facing direction and tilt angle of solar panels in order to maximize the time throughout the day when solar panels produce enough energy to run the pump. It was assumed that it would be maximized with parallel circuit of half solar panels facing towards east and half towards west that would increase their power output during morning and evening hours and decrease during peak hours. The power output’s examination was conducted in Excel on various location latitudes and longitudes, solar module tilt angles, facing directions and days throughout the year. The calculation demonstrated independently on the location that solar panels facing east and west can increase operation hours in summer periods by 20%, but during winter periods losses are greater than 50%. It was concluded that throughout the year the maximal operating time is achieved with solar panels facing directly to the north in the southern hemisphere and directly to the south in the northern hemisphere with a tilt equal to the latitude. The second part of this thesis is designing a DC/DC converter with charge control for charging and discharging supercapacitors in order to supply the pump during power fluctuations and short term intermittent periods. The experiments showed that the system can supply a pump during intermittent periods up to 2:20 minutes, while the majority of intermittent periods last less than a minute. Therefore, this system can improve the efficiency of a standard PV-RO water treatment system.