MPPT Charger - Buy or DIY ?

Hello!

For my new project I need your support!

I would like to equip my model airplane with solar cells so that it
can charge the batteries during the flight and thus ensure a longer 
flight time .
Of course I want everything to be as light as possible, including
Electronics, especially the MPPT charge controller.

My question : Have any of you ever designed a charge controller yourself
? Or can someone give me an example for a light and
small charge controller?

I dare to develop a corresponding circuit board, but
it is often easier to fall back on already proven electronics
(my experience).

Is it possible to reach the goal with an Arduino?

I look forward to your answers!
Many thanks in advance :)