I have not wanted to explain why your project will not work. Here goes.
A buck boost PWM is not smart and will not work well with a solar panel.
To get the most power from a panel you should work at the Max Power Point which is above you battery voltage so "boost" is not needed.
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Data: 22.1 volts, 2.2 amp, 36 watts, Blue Solaria Co., Ltd..
36 watt panel. (No one has ever got 36 watts) I live at high altitude, 10% humidity, thin air, no clouds and I can't get 36 watts. Close but no 36 watts. I have friends that live sea level, 95% humidity and they get less power. You can not multiply the voltage and current to get power. The voltage is measured with no load and the current is measured into a short.
22.1V open circuit
2.2A at a short
Maximum power point is about 18 volts (2.0A)
View attachment 107729
Pretend it is a very bright day. Use top green line and top blue line. Top left corner of the graph is 2.2A into a short. (2.2A 0V 0 watts)
Bottom right corner is the open circuit no load point. 22V, 0A 0 watts.
At 18V and 2.0A we get 36 watts. (max power)
If you pulled only 1A you will get 20V and 20 watts.
If you pulled 2.1A you will get 15 volts and 31.5 watts. (down from 36)
If you pull 2.2A the voltage will drop to 0 volts and 0 watts.
What we learned is to pull power until the voltage drops to the MP point. Do not pull any more current.
---------early morning-------- not bright-------
Use the bottom green and blue curve.
Short current is 200mA, open voltage is 19V and the max power point is about 18V.
18V 180mA 3.24 watts is the sweet spot.
If you try to pull anything over 3.24 watts the voltage will fall to zero.
-----------------------------Max Power Point---------------
I looked at several MPPT controllers that are built to charge batteries.
They have 3 adjustments.
1) max battery voltage. 14.5V for a 12V car battery.
2) max battery current. Your battery probably can handle more than a 2A panel can produce so it could be set to 3A. (mostly not used)
3) max power voltage from panel. In my example 18 volts.
If the battery voltage gets too high the PWM will back down.
If the battery current get too high for the battery the PWM will back down.
The PWM will increase/decrease the power to hold the panel at the best voltage.
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If the panel voltage drops below 12V (where boost might help) the power level is much less than one watt and not worth the effort.
Hope this helps.