Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE credits
In present scenario grid connected photovoltaic systems are widely deployed in towns and cities as they can contribute to better environment. They also have advantage of generating significant quality of energy near the consumption point by avoiding transmission and distribution losses. In any grid connected system one of the main components needed would be the inverter for delivering AC output to the grid. The key issue to have best output merely depends on the sizing of the component. Factors influencing the sizing of the components in the PV system are components technology, climatic aspects of placements of inverter installed and solar radiation distribution characteristics that, of which location and climatologically plays a major role. In places like Sweden and most parts of northern European countries, under sizing of the inverter in PV grid-connected systems is recommended. This is because solar radiation reaches seldom values around 1000 W/m2 which PV modules are rated for. There are also many cloudy days when the inverter would operate in 5-20% of the nominal range where inverter efficiencies are significantly lower than for higher radiation. Thus leading to cost efficient photovoltaic grid connected systems though there might be certain amount of energy losses in the system.
Operating at higher or lower ranges reduces the efficiencies of inverters to some extend due to technical implications of the device. In this thesis, the optimal sizing factor of inverter will be studied, besides the energy yield, the cost and expected life time of the inverter shall also be taken into account. For more appropriate results three different locations that covers south, middle and north part of Sweden is taken into account. A life cycle analysis is also done based on system yield simulations, data from the literature and cost data provided by the government norms of Sweden.
The thesis will also investigate on the effect on life time of the inverters data influences the results due to undersize compared to the PV array and how much the maxima smoothes out due the time resolution of the radiation. One hour average data might mislead as it averages out some of the peak radiation. Comparisons between hourly averages and minute wise global solar radiation is done and analyzed.