photovoltaic panel load problem

[mshh]

I am doing maximum power tracking (MPPT)for a photovoltaic cell (max current 4.8 A ,max voltage 34 v) i did this circuit [url=https://obrazki.elektroda.pl/8348410600_1385718504.jpg][/URL]to control current consequently get MPPT but the circuit go mad when i turned the potentiometer the current go up and down and didn't stabilize .

I used this power supplyhttp://www.amazon.com/Mastech-HY3005.../dp/B000E14F56 to simulate the pv panel and adjust it to source 7 volt and it did well . i could change the current from 0-2 A when i tried to increase it upper than 7 v it went crazy . the led indicator called C.C changed to C.V every thing current and voltage go upside down ,and that what was happening with the pv panel. i don't know why . may be i should increase the number of mosfets.

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I am doing maximum power tracking (MPPT)for a photovoltaic cell (max current 4.4 A ,max voltage 34 v) i did this circuit [url=https://obrazki.elektroda.pl/8348410600_1385718504.jpg][/URL]to control current consequently get MPPT but the circuit go mad when i turned the potentiometer the current go up and down and didn't stabilize .

I used this power supplyhttp://www.amazon.com/Mastech-HY3005.../dp/B000E14F56 to simulate the pv panel and adjust it to source 7 volt and it did well . i could change the current from 0-2 A when i tried to increase it upper than 7 v it went crazy . the led indicator called C.C changed to C.V every thing current and voltage go upside down ,and that what was happening with the pv panel. i don't know why . may be i should increase the number of mosfets.

but i used four resistors 3.3Ω 7 watt instead of those in picture

 

[BradtheRad]

I don't know for sure that this is the problem...

But your op amp is arranged to be a voltage follower.

Suppose you were to reduce the gain? By installing resistor feedback to the inverting input, where you presently have plain wires? Then your op amp output might react mildly, and become more controllable?

 

[mshh]

how could it be a voltage follower and the Mosfet is supposed to have resistance. even if it is a voltage follower this is not the problem now .