For more than two years, SolarCity Corp. has been trying to launch an experiment that could change the way we power our homes.

The San Mateo company has installed battery packs in more than 100 houses throughout California, each pack linked to rooftop solar panels. The lithium-ion batteries, made by Tesla Motors, store electricity from the panels during the day for use at night.

That combination - solar on the roof, batteries in the basement - could one day revolutionize the energy industry, undercutting traditional utility companies.

So the utilities, SolarCity says, are fighting back.

California’s big electricity providers are dragging their feet on connecting the batteries to the grid and charging steep fees - nearly $3,700 per customer, in some cases - to do so, according to SolarCity.

“We all know this is a game-changing product,” said SolarCity CEO Lyndon Rive, speaking at a recent public forum in which he complained about the delays. “Those in the game don’t want to change the game. They really like the existing game.”

SolarCity, which made its name leasing solar arrays to homeowners and businesses, quietly started offering batteries to its residential customers in November 2011. More than 500 have signed up so far. Of those, just over 100 have received their battery packs.

But most of them still can’t use the batteries.

Only 12 connections

Since the pilot program started, utilities have only connected 12 of those battery systems to the grid, according to SolarCity. Pacific Gas and Electric Co. has hooked up 11 customers, while San Diego Gas and Electric Co. has connected one. Southern California Edison has not connected any, even though SolarCity has submitted 10 applications to the utility.

Lee Middleman of Portola Valley has been waiting almost four months.

Longtime SolarCity customers, he and his wife, Donnie, jumped at the chance to add a storage pack when the company started the program. They belong to a community emergency response team and understand the value of being able to generate and store their own electricity if the grid goes down.

“It’s a little remote, here, and when the power goes out, it’d be nice to have a backup system,” said Middleman, a ceramic artist. “If there’s an earthquake, we know Portola Valley is going to be one of the last places PG&E will service, because they’re going to start with the more densely populated place first.”

But for now, the battery pack, complete with Tesla logo, sits unused. (Tesla CEO Elon Musk chairs SolarCity’s board of directors, and Rive is his cousin.)

“It seems like they’re throwing every possible roadblock in front of this thing to slow it down,” Middleman said.

PG&E charges $800 for each application, plus a $600 fee whenever the utility decides that the solar-and-battery system needs a new electric meter. Southern California Edison charges the same application fee, plus $2,898 to install and connect the meter, according to documents SolarCity provided to The Chronicle.

SolarCity contends that the application fees are illegal, saying they conflict with a state law that governs how utility companies deal with home solar arrays.

Won’t rush

PG&E insists it is not trying to block or delay SolarCity’s energy storage program. But Steve Malnight, PG&E’s vice president of customer energy solutions, said the company won’t rush its process for inspecting the new systems and connecting them to the grid. The current wait time, he said, is eight to 10 weeks.

“We’re not satisfied with that time, in the long run, but this is a new technology,” Malnight said. “Our focus is on ensuring safety and reliability for the customers. I think that’s appropriate.”

A Southern California Edison spokesman was not able to comment for this story by press time.