The man, who denies crime, was charged with public destruction and violation of the law on flammable and explosive goods.
He is now sentenced to prison.
According to the district court, the penalty is imprisonment for four years, but because he was 18 years old when the crime was committed, the sentence will be two years' imprisonment.
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Here it explodes at the villa in Upplands-Bro Photo: Crime scene Sthlm / Marco Blomberg / STHLMNEWS
The man was also charged earlier this week with a serious drug crime and a serious gun crime in a large investigation in Norrköping.