Huvudsta, the closest underground station(blue line), is a 10-minute  walk from Campus Solna. There are four stops between Huvudsta and T-centralen(Stockholm city center) and the ride takes approximately 15 minutes. Going to the University, you change platforms at T-centralen, and take the red line towards Mörby Centrum. Getting from T-centralen to University will take You another 10 minutes. Going by bike it will take You about 25 minutes. There is plenty of room to park your car for free at the campus.