This work deals with a mppt techniques and multifunctional control algorithms of a three phase grid connected solar pv (photovoltaic) system, which is based on fza-nlmf (fast zero attracting-normalized least mean fourth) algorithm and other robust control algorithms. these control algorithm achieves the objectives of mitigation of power quality issues such as harmonics reduction and power factor correction together with extraction of peak power generated by the pv array. the system uses a pv array, a vsc (voltage source converter), linear and nonlinear loads. here, vsc is connected to a pv array to transfer the active power to the three phase load and the grid. the dependency on tuning of proportional-integral (pi) controller is reduced because of feed-forward term of the pv power. due to this, the system dynamic response is improved, which makes the system quite robust. the system goals are to mitigate power quality problems and to provide current conditioning while operating in coherence with a weak distribution grid, which has poor quality of power, in terms of voltage distortions with imbalances. matlab/ simulink is used to develop the model of the proposed system. the validation of proposed control is done at varying linear and nonlinear loads and under different environmental conditions on a prototype developed in the laboratory. the major objectives of this work are as follows. • harvesting of highest extent of power from pv array and to supply that power to a distribution feeder and connected linear and nonlinear loads as well as to solve the power quality problems via spv-dsatcom system. • an implementation of fza-nlmf adaptive technique and other novel control techniques for extricate the fundamental components of load currents. • to mitigate the effect of imbalances and distortion in distribution feeder voltages on distribution feeder currents. • effective use of power electronics equipment such as vsc. • maintaining the stability of the system at connected linear and nonlinear loads and under unbalanced loading. • developed a novel mppt technique for single stage and double stage segs topologies with three phase grid tied inverter • developed an intelligent and robust multifunctional spv-dsatcom topologies for three phase distribution feeder with abnormal grid condition. the proposed topologies, mppt techniques and multifunctional control algorithms are designed, modelled for a single stage and two stage 3-phase grid integrated solar pv system, which is simulated in matlab platform (matlab version –matlab r2014b, toolbox used- sim-power system (sps) and simulink blocks) and for validation, a prototype is developed in the laboratory for unity power factor mode and mitigating harmonics and load balancing. furtermore, this research work mainly focus on investigation on grid interfaced solar pv power generating system such as multifunctional spv-dstatcom and grid tied inverter with new mppt technique. in spv-dstatcom system, it transfers active power to grid as well as connected loads while mitigating the pq issues in the distribution system. in spv-statcom system, it transfers large power at high voltage to three phase ac grid with statcom capabilities. in both system, the vscs are fully utilizing the full capacity of the proposed system in 24 hours. to do these multiple functions, an intelligent control algorithm with maximum power point tracking method are designed and modelled under varying loads and environmental conditions with abnormal grid condition. to improve the efficiency of the system, an intelligent and robust control technologies with different topologies are adopted over conventional techniques in the spv grid tied system. some of the configurations and new control algorithms have been implemented in the laboratory under varying conditions in this work. the major focus of this work is to increase the efficiency of system while transferring large active power to grid as well as mitigating pq issues with nominal and abnormal grid condition both. govt. of india has an extensive plan to generate more green power from sustainable renewable energy resources from grid tied roof top solar pv system. therefore, a modern state of art for design and development of grid interfacing solar pv system for roof top applications research infrastructure is highly required in india for carrying out extensive research in this area.