In theory of electric universe, Sun swallows interstellar matter and is shining with its electrical energy.  Sun takes in the interstellar material from both polarities of the north and south, and releases it from the vicinity of the equator. The black spots appearing on the surface of Sun are thought to be visible inside, with the gas in the convection layer dislodged.  The convective layer of 200 km thick gas is the base of solar activity.

There are interesting figures.

• Volume of Sun → 695700 km Volume of hydrogen gas (thickness 200 km) →1.2 x 10 ^ 15 km3
• Jupiter's radius → 69911 km volume → 1.4 × 10 ^ 15 km3
• Saturn's radius → 58232 km volume → 0.8 x 10 ^ 15 km3

Sun's surface, the volumes of 200 km gas and Jupiter, Saturn are about the same.  The inside of Sun may be a hollow.

Accoding to "Missing matter in the Sun’s interior",

Based on the vibration appearing on the surface of Sun, when he tried three-dimensional simulation, it resulted in nothing inside.  In this paper he conclude that high temperature, high pressure substances are not transmitting vibration or dark matter exists.

By the way, there are large oscillation that occur every 5 minutes in Sun.  Solar oscillation is a phenomenon in which the size of Sun is several tens of kilometers wide and grows or decreases.  Solar oscillation turns into sound waves of solar wind and creates a standing wave throughout the solar system.  The solar wind standing wave stabilizes the revolution of the planet.

Why does solar oscillation occur?  Solar oscillation can be explained well assuming that the interior of Sun is hollow.  Many of the interstellar substances flowing into Sun are protons.  The amount of interstellar material flowing in is not constant. As the proton increases, the positive charge increases, so the internal repulsion increases and the size of Sun also increases.  As Sun gets bigger, the solar wind runoff increases as the surface area increases. As the solar wind leaves more gas, the size of Sun will be smaller.  Solar oscillation plays a role in adjusting the size of Sun.  There is also the role that the output of Sun is kept constant.

It is a hypothesis that the interior of Sun is hollow.  However, there is also the theory that Saturn was shining once. "Purple dawn Saturn" is a very attractive hypothesis.

Sun is bulging from the inside with a positive electric repulsion force, and the outside is pressed by the rotating magnetic field by the current flowing in the plasma.  That is why Sun is almost spherical.

6000 degrees of gas on the surface of Sun may be making heavy elements such as iron.   Sun may be making heavy elements from protons of interstellar matter. If there are more substances to store negative charges such as rocks in Sun's hollow, Sun will deflate.  Sun may change to a gas planet like Saturn, Jupiter.