Have you Googled;
arduino mppt
This will be very helpful to you.
Tom.. 
Yes, I have done that. But I just researched a few of them, got a simple understanding of it. Because I want to learn it myself, I try to design it myself.
Do you understand that a PV cell is a current source, not a voltage source?
Tom..
I doesn't take much to blow-up a MOSFET.
A single nanosecond range pulse greater than VDsss (100V) can destroy it.
If your solar panel can go as high as 90V then I'd use a 150V-200V MOSFET.
Also put a small series gate resistor in the GateDrive line, maybe 33 ohms.
It will slow down the MOSFET turn-on and reduce any transients.
I understand that its a current source. How should that change my train of thought?
Hello! I got the new mosfet and igbt driver, tested it on a breadboard, and with my calculations it is running at about 95% efficiency, which I think is not bad at all if its right. I checked with a thermal camera, and the mosfet heats up quite alot, 55° celcius, but it is easily cooled.
Though the gate signal at 100kHz looks quite ugly. Is it ok, is it bad, is there a way to minimize this?
If I disable the main power supply, then it looks like this. The undershoot becomes smaller
What do you mean "main power supply"
I am using 2 power supplies, one for the gate driving, and the other one, powers the load being switched by mosfet.
I forgot to add that at this point I have made up the circuit on a breadboard.
You need o provide an updated schematic.
The MOSFET should not be getting HOT unless you are drawing a LOT of current
I was drawing only about 1.2A. At 40V it was about 50W. I am guessing it is not enough current for the mosfet to get hot at normal operation?
When it is is fully ON the MOSFET has a resistance of 0.077 ohms.
The power dissipated by the MOSFET = I^2 X R (I squared times the resistance)
So 1.2^2 X 0.077 = 100mW
It should not be getting hot at all
You are doing something wrong somewhere.
Could these massive oscillations on the output of the mosfet be the reason? As running it at 1kHz, it doesnt have them, and the mos doesnt heat up.
I need a schematic to know what you are doing.
Probably due to sharp rising edge and the impedance mismatch, signal reflections and the circuit inductances.
Add a series gate resistor to slow the rising edge.
I am going to draw a schematic in a bit!
Adding a 100 ohm resistor minimized the rising edge oscillations quite nicely, didnt affect falling edge at all. Though I added a reverse diode to my load, as its a coil of nichrome wire so an inductor, and it minimized the falling edge a bit.
Still heating up tho
It'a trade-off. Slowing down the turn-on/off will cause it to disipate more heat
The circuit I have made up right now looks something like this, basically the same thing as in the original buck circuit.
Hi,
Is the 40V supposed to be your PV panel?
How much current is coming from the 40V supply?
Is the load really 1K?
I think this will change when you make your load a battery to charge.
Can you please post some images of the above project configuration?
Thanks.. Tom..
I am not using a solar panel right now, instead I am just using a power supply. My load isnt 1k, I didnt measure it, but ohms law says its about 33ohms. The biggest problem for me right now is that the efficiency of my mosfet drops when I increase the switching frequency.