1. The defendant's appeal is dismissed.

2. According to the plaintiff's expansion of the purport of the claim in this court, the defendant shall be the plaintiff.

1. In the first instance trial, the Plaintiff asserted revocation of mistake in relation to the office building that the Plaintiff acquired against the Defendant, and filed a claim for the return of unjust enrichment in relation to the acquisition price, and the claim for damages equivalent to the amount of unjust enrichment in the event that such revocation is not recognized, or for damages arising from defects in the construction of solar power plants executed by the Defendant.

The first instance court partly accepted the plaintiff's claim related to defects in the construction of solar power plants and dismissed all of the plaintiff's claim related to the office building.

Accordingly, only the Defendant appealed against the claim for damages against the defects in the construction of solar power plants. The Plaintiff filed an incidental appeal in this court, but at the fifth date for pleading, stated that the part of the claim related to the takeover of office structures was not included in the purport of the incidental appeal, and the above purport of the incidental appeal is against other parts of the construction of solar power plants, which were not determined by the first instance court. Thus, the subject of the judgment by this court is limited to the claim related to the defects in the construction as cited by the first instance court and the claims added by the Plaintiff in this court.

2. The reasons for the acceptance of the judgment of the court of first instance are as follows, except for the addition of the following "3. Additional Judgment" as to the allegations emphasized or added by the defendant in this court and the claims extended by the plaintiff in this court, and therefore, they are cited by the main sentence of Article 420 of the Civil Procedure Act.

3. Additional determination

A. As to the assertion that there is no cause attributable to the defect of the first solar power plant in the determination on the Defendant’s assertion emphasizing or adding, the Defendant used an error in the Plaintiff’s construction of the roof mash of the first solar power plant.