California has just 300,000 electric vehicles – far short of Gov. Jerry Brown’s goal of 1.5 million by 2025. A new report says one of the biggest barriers to getting more electric cars on the road is a lack of places to plug in.

In the past, the price of electric cars was an impediment to their adoption. But cost is no longer as daunting as electric car batteries have gotten cheaper, subsidies have increased, and dealerships have begun offering affordable leases.

Now, the question of where to charge is a bigger issue, especially for the 40 percent of Californians who live in multi-unit apartment buildings, said Ethan Elkind, lead author of the UCLA and Berkeley Law school study. Many of them don't have a dedicated parking spot, which makes it difficult to charge an electric car at home.

"It's really telling that 80 percent of electric vehicle drivers live in a single family home," Elkind said.

There are two big problems with increasing access to charging for apartment-dwellers. The first is convincing landlords or employers to install chargers.

The average installation cost for a charger is $2,200, according to the Idaho National Laboratory. In California, a 2014 law requires landlords to allow their tenants to install electric chargers -- but it doesn't apply to rent-controlled buildings and those with fewer than five parking spots.

Another issue is the cost of electricity. Public chargers, like those at malls or near highways, and those at workplaces are subject to commercial electricity rates, which are higher than residential rates. At times, it can cost so much to charge an electric car that it makes more sense to drive a gasoline-powered vehicle.

The report offers an array of possible solutions, including:

Incentives to bring down the costs of installing chargers at workplaces

Changing commercial electricity rates to make public charging more cost-effective

Re-jiggering municipal parking rules to allow for curbside charging

Building public charging "plazas" where apartment-dwellers could leave their cars parked overnight.

The challenge is daunting. As the report notes, "to meet the 1.5 million electric vehicle target by 2025, the state will need to see an exponential growth in electric vehicle sales."