Since Tesla launched its “Powerwall” system in 2015, home battery storage for solar panels has risen from an interesting hypothetical to one of the most talked about energy products out there, driving interest from tens of thousands of potential buyers and Vermont’s largest utility.

The flurry of interest surrounding home energy storage prompted me and my colleagues at the University of Texas at Austin to attempt to cut past the hype and understand exactly how storing solar energy to reduce reliance on the utility would really affect both consumers’ utility bills and the wider electricity system. Our efforts culminated in a paper published today in the journal Nature Energy titled “The impacts of storing solar energy in the home to reduce reliance on the utility.”

Our study found that storage provides a benefit in the form of reduced power flows in the distribution grid, which can lead to utility infrastructure cost savings. However, because some energy is lost every time a battery system charges and discharges, storing solar energy for later use in the home actually increases energy consumption versus just sending it directly to the grid. And with today’s fossil-fuel powered electric grid, the increase in energy consumption also leads to an increase in overall emissions.