The initial results of pilot programs on plug-in electric vehicles may spook companies and create a vicious cycle of inefficiency when it comes to charging.

That's according to one of the topics covered in the "Changing the game: Plug-in electric vehicle pilots" report (PDF) released yesterday by technology consulting giant Accenture.

The Accenture report examined the recent data garnered from over 25 pilot programs scattered around the world that have been monitoring EVs and driver habits.

Overall the pilot programs found public charging stations have not yet been getting enough use to pay for themselves and their installation, according to Accenture.

This discovery is attributed to the fact that there are not yet enough EVs on the road to fully make use of public charging stations, and that the small number of EV drivers have formed a habit of charging at home at the end of the day because initially their home charging station was the most readily available option. The recent introduction of more public charging stations has not yet changed this home charging habit, according to Accenture.

The Accenture report says that attracting local businesses to invest in public charging stations will become harder as news spreads that these pilot programs are discovering that lack of use means the public stations are not paying for themselves.

This could form a cycle in which, because there are not enough EV stations to form a reliable public infrastructure, people organize their lives such that they charge in the evening or at night in their homes. Then, because of this habit, new public stations won't get much use, and businesses will be discouraged from investing in them, according to the report.

So why is it an issue if society switches from generally fueling cars at public stations to fueling cars privately at home

An abundance of people in a community with the same charging habit at the same time of day could lead to a strain on the local electric grid, according to Accenture.

The pilot programs found that typical EV drivers really do drive fewer miles than their EV mileage range in a single day, so many people don't even charge their cars every evening--they can get by on every two days or more.

One might think this is a positive discovery to come out of EV pilot projects, but the Accenture report has other thoughts.

"Pilots show that PEVs meet the driving requirements of typical city users who may therefore not plug in their cars daily. This increases the unpredictability of charging and reduces control. Plugging in vehicles whenever parked will help grid management, easing the strain on the grid," said the report.

Battery swapping, such as the service provided by Better Place, which operates battery-swapping stations, might provide an option to better managing grid use for EVs, according to the report.

Accenture, however, notes that it did not include pilot programs in which EVs were used in conjunction with distributed grid storage, or vehicle-to-grid technology, which might have different results with regard to grid strain.

"It is our view those pilots will become more significant as the technology and business models begin to stabilize," said the report.

The report also makes no mention of how programs offering peak-pricing and smart-meter tools as a way to control peak electricity use in consumers might work in conjunction with EV home charging. This could be because those pilot programs, such as the U.S. EV Project, which plans to do a 15,000-car study to determine the habits of EV owners and their affect the electrical grid, are generally in the early stages.