Comprehensive desing for controlling and modelling of an off-grid pv system at maximum power output

Using conventional energy sources causes air pollution and global warming at the present time. Many countries have conflict in sharing fossil-fuel-based sources. However, the sun has been a major energy source since the world exists. The energy that comes from the sun is to such a degree that it makes it meaningless to fight for the energy. The only thing to be considered is to find how to use it properly.Today, the solar energy is used widely in water boiling-heating and electricity generation. We are not interested in boiling and heating water, but the sun tracker that was designed and constructed in this study can be used for such operations.It is well known that the efficiency of photovoltaics that produces electric energy from solar energy is significantly low. The cost of photovoltaic systems is quite high. Considering all these disadvantages, doing work on photovoltaic systems that gets the most efficient results will decrease the cost of the systems while it increases the interest in these sources.This dissertation focuses on three significant subjects:First, the maximum power point of PV (Photovoltaic) panels was tracked using the linear region characteristic of semiconductor switches on a dc-dc chopper (Boost converter). Being so different from classical methods, this work presents a simple method that determines maximum power point without adding any additional circuit to power systems. In this method, the real MPP (Maximum Power Point) of the system is always determined in a precise manner by eliminating local MMPs. Being stable, fast and compatible with all the systems will increase its widespread usage.Second, a new tracker classification was developed considering advantages and disadvantages of existing trackers. Open and closed-loop methods were implemented separately on the prototype with a microcontroller. In open-loop, sun tracking is achieved by using geographical location, date and time information while sun tracking is achieved in closed-loop by evaluating the panel open circuit voltage. In addition, fixed and two-axis trackers were compared in performance with the measurements taken in sunny days. The correctness of the results was verified by means of a computer simulation. An important aspect of the work is that the tracker system in this prototype was implemented in an industrial type PV system with 1.75 kWp power.Third, battery types were mentioned shortly. The structure of the battery types and various charging techniques used widely in today?s PV systems were explained in detail. After the control system determines the maximum power level, batteries are fed from the chopper in the way that they get the most appropriate power from PV using various charging techniques.