The theories and formulas are "complicated" to keep people from just saying, straight out, they are wrong.

Everything from Einstein is completely wrong.
But the people behind it set it up like this:
Einstein is a great genius. The very smart of the smart.
No one can understand his theories, so who are you to question them?

The actual formulas of the universe are very simple.

Solar panel electrical is very simple.
Very straight forward DC electricity.

And if you break the solar power system into its two parts, each one is extremely simple.
The battery charging side
The power conversion side (converting 12V DC into 120V AC)

Buy all the pieces from harbor freight and play with them.