Tesla is to build a network of solar-powered superfast chargers along US highways that should allow owners of its electric Model S sedan to travel for free.

The company yesterday unveiled the first six chargers in California and said by next year it plans to install the devices across the continental US, enabling electric travel “from Vancouver to San Diego, Miami to Montreal and Los Angeles to New York”. Chargers in Europe and Asia are set to follow in the second half of 2013.

The chargers provide power at 100kW, replenishing three hours of 60mph driving in the Model S sedan in about 30 minutes.

Co-founder and chief executive Elon Musk told news agency Bloomberg the devices cost around $250,000 each and can power four to six cars simultaneously. He added the company expects to fit 100 chargers at a cost of between $20m and $30m over the next three to four years.

A solar power system developed by Musk-backed SolarCity is designed to generate more electricity over the course of a year than is consumed by Tesla vehicles using the supercharger.

Outside of installation costs, the rocket-shaped chargers will cost the company so little it said it may offer Model S buyers free electricity indefinitely.

“By making electric long distance travel at no cost, an impossibility for gasoline cars, Tesla is demonstrating just how fundamentally better electric transport can be,” Musk said in a statement. “We are giving Model S the ability to drive almost anywhere for free on pure sunlight.”

The Model S is said to have the longest range of any production electric car in the world and comes with three different battery options that mean prices range from $49,900 for the lowest-spec model to $97,900 at the top of the range.

Tesla announced earlier this year it is unlikely to reach a target of delivering 5,000 Model S sedans this year because of supplier problems. However, it expects to generate around $46m in third-quarter sales and company executives have repeatedly expressed confidence Tesla can deliver at least 20,000 Model S sedans in 2013, achieving a gross profit margin of more than 25 per cent.

Tesla has received $465m in loans from the US Department of Energy and said yesterday in a regulatory filing it has until the end of October to submit a proposal for “early repayment”.

Deepak Ahuja, the company’s chief financial officer, told Bloomberg Tesla will meet the deadline for the revised payment plan and will be able to pay back loans in less than the existing 10 year term if it becomes profitable ahead of schedule.

In related news, Autogas Limited has opened the first LPG (liquefied petroleum gas) refuelling station on the M25 at Shell Cobham. The company, a 12 year old joint venture between Shell and Calor already operates 215 stations providing the low-emissions fuel on forecourts throughout the country and aims to open 18 sites over the course of this year.

Paul Oxford, head of business development at Autogas, called the development a “significant milestone for the country’s growing LPG market: there are 165,000 LPG powered cars in the UK and 12,000 were converted to run on the fuel last year.

“More and more motorists are converting to LPG, the cheaper and cleaner fuel,” he added. “So it’s important that Autogas Limited is able to provide easily accessible refuelling points throughout the UK and particularly the motorway network to the increasing number of LPG users.”