Does the change in load affects maximum power point in PV systems? (I think the answer is Yes). Then, why do all MPPT techniques only concern themselves with the changes in environmental conditions (irradiation)?
The maximum power point of a PV array is a feature of the array and the incident solar radiation at the time. If the load does not draw this amount of power, the MPPT automatically operates the array at a working point where the output power matches the load - you aren't working at maximum power point because there's nowhere for the excess power to go. If the load wants to draw more power than the array can supply, then you have a problem and what happens depends on the load. Most likely the output voltage falls, reducing the power the load requires. Some loads stop working when this happens! MPPTs are most useful when driving an 'infinite' load like the network - or a battery. If all you have is a few lamps you might not even need an MPPT.
the papers care more about radiation because they consider constant load but there are other papers consider the load changes along the IV curve.
load optimum = Vmpp/Impp
The maximum power point of a PV array is a feature of the array and the incident solar radiation at the time. If the load does not draw this amount of power, the MPPT automatically operates the array at a working point where the output power matches the load - you aren't working at maximum power point because there's nowhere for the excess power to go. If the load wants to draw more power than the array can supply, then you have a problem and what happens depends on the load. Most likely the output voltage falls, reducing the power the load requires. Some loads stop working when this happens! MPPTs are most useful when driving an 'infinite' load like the network - or a battery. If all you have is a few lamps you might not even need an MPPT.
MPPT technique is employed to track the MPP of the PV cell depending on the I, V samples collected from the PV. The output voltage of PV cell is directly depend upon the Solar Illumination. If the solar illumination varies the output voltage of PV will vary. In order to have a constant DC output voltage a boost converter or buck-boost converter is employed as per the desired output voltage level. In this scenario change in DC load will not effect the MPP of the PV. So, MPPT will be tracking the MPP of the PV panel their by adjusting the duty cycle of the converter to meet the required load at constant output voltage.
Please refer to these articles:
https://www.researchgate.net/publication/309716325_Designing_And_Simulating_Of_Micro-controller_Based_on_PWM_Solar_Charge_Controller
https://www.researchgate.net/publication/315692275_Maximum_Power_Point_Tracking_Control_of_PV_Electronic_System_using_Neural_Network
Article Designing And Simulating Of Micro-controller Based on PWM ...
Conference Paper Maximum Power Point Tracking Control of PV Electronic System...
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