I had a similar problem with mine getting condensation and dripping all over the electrics, so, i managed to get hold of some secondhand polycarbonate sheets (the stuff for conservatory roofs) and screwed that to the underside of the roof joists and sealed all the gaps from the inside, that way the heat was contained inside thegarage rather than going up to the joists and metal roof, i also made sure the were plenty of vents above the polycarb layer to allow airflow below the metal roof, havent had a drip since.
I keep checking the polycarb and so far no signs of any drips on it yet after several years