Expanding Earth- Can’t be, or has to be?

It strikes me as strange that geologists seem to think the earth isn’t expanding because tectonic plates slide under one another in subduction. It is known that photons are emited from the nuclear reaction that is our sun, carrying energy that was once part of that sun, and that that reaction will one day cease and the sun will die. In the meantime chlorophyll molecules are busy turning the small amount of energy carried by those photons into the pre-cursors of carbohydrates. Admittedly, plants use some of their energy for respiration, and some will be eaten by animals, which will turn some of that chemical energy into kinetic and thermal energy, so on and so forth. However far up the food chain it goes, a proportion ends up back in the earth, as can be seen from the strata of rock. If energy from the sun is being turned into matter on the earth, then surely the earth must be getting more massive. It’s obvious isn’t it?