Question: When was the star to which Solgränd is named after discovered to be the center of the solar system?

Knowledge 1: Solgränd
Solgränd (Swedish: "Sun Alley") is an alley in Gamla stan, the old town of Stockholm, Sweden. It connects the Stortorget square to the street Prästgatan. It is a parallel street to Storkyrkobrinken, Ankargränd, Spektens gränd, and Kåkbrinken. [SEP] Knowledge 2: Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~ 73%); the rest is mostly helium (~ 25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.
Knowledge 1: Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~ 73%); the rest is mostly helium (~ 25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. [SEP] Knowledge 2: Solar energy
It is an important source of renewable energy and its technologies are broadly characterized as either passive solar or active solar depending on the way they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Knowledge 1: Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~ 73%); the rest is mostly helium (~ 25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. [SEP] Knowledge 2: Heliocentrism
Heliocentrism is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System. Historically, Heliocentrism was opposed to geocentrism, which placed the Earth at the center. The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by Aristarchus of Samos, but at least in the medieval world, Aristarchus's Heliocentrism attracted little attention -- possibly because of the loss of scientific works of the Hellenistic Era.

Answer: as early as the 3rd century BC