Bareiß was speaking at the Bloomberg New Energy Finance (BNEF) Future of Energy Summit in London (1-2 October).
He told delegates the move to an auction-based system had been "very successful" in bringing down the cost of energy in Germany.
But renewable energy's resulting expansion has outpaced the development of the grid.
"We have come far in expanding renewable energy especially in the electricity sector. In 2017 renewable energy sources covered more than a third (36%) of gross electricity consumption. As renewables are becoming more important they need to be integrated into the market and to respond to price signals," Bareiß said.
"Renewable power is mainly generated in the north part of the country yet energy demand is more in the south where the industry is. Energy generation is now more distributed over Germany than before.
"There are more points where we feed renewable energy in to the grid than there were with fossil fuels.
"We will invest about €50bn until 2030 in to the electricity grids, the largest part of this investment goes to transmission.
"More then 7,500km of transmission will need to be upgraded or newly constructed in the next few years. Currently we are far behind our ambitious targets.
"That situation is causing large costs. At the end of the day consumers and businesses have to pay for this."
With Germany focused on grid infrastructure, Bareiß said the growth of renewables through auctions would need to be taken at a steady pace.
"As we expand renewables further, we need to maintain a sufficient level of competition. We must not expand too quickly otherwise we will have a low number of bidders.
"These would lead to higher funding rates. Therefore we need to move forward at a reasonable pace," he said in London.