• Megafactory in Nevada will produce 500,000 batteries annually.
• 'It will produce more batteries than all other factories in the world combined.
• The factory will be used to produce batteries for Tesla Model 3 car.
Tesla's Gigafactory in the Nevada Desert is finally nearing completion.
Set to open on July 29th, it will have the largest footprint of any building in the world.
The $5 billion structure will produce 500,000 lithium ion batteries each year to meet demand.
The official invitation sent by Tesla via email went out to existing Tesla owners that participated in the company's fourth referral program by referring 4 or more qualifying sales.
Lucky owners will be given a tour of the new facility, and are expected the be shown the latest progress of the firm's Model 3 car.
Guests will be allowed test drives and factory tours before and after the 'remarks' at 9 PM.
However, Tesla has not mentioned the test-drive vehicles.
Recent drone footage gave a glimpse of the vast structure.
The footage shows little progress on the exterior of the building, but Tesla appears to have been working on the area around the plant.
Musk said the Gigafactory and its Fremont facility would produce more lithium ion batteries in a year than were produced in the entire world in 2013.
In terms of sheer size, the Gigafactory is second in volume only to Boeing's airplane factory in Washington.
But when it comes to how much ground it covers, Tesla's upcoming factory is the largest in the world.
"This is a vital element," Musk said in his presentation of the Model 3. "To give you a sense of scale, the Gigafactory will have the largest footprint of any building of any kind."
"Our Fremont factory in the past has actually made 500,000 cars a year, so we're confident Tesla can achieve that in the future in terms of vehicle production," he said.
"I think that's going to be, I wouldn't say straight forward, but very doable.
But what about batteries? In order to produce half a million cars a year, we basically need to absorb the entire world's lithium production 'That's the entire reason we're building the Gigafactory.
"It will produce more lithium ion batteries than all other factories in the world combined...We will also be producing the most advanced cell in the world."
The Gigafactory is now producing battery packs but not yet creating the cells inside, Musk revealed.
The huge project is part of the billionaire's plan to drive down the cost of electric cars and create home battery packs to provide cheaper electricity.
The Model 3 costs $35,000 in the US - half the baseline price of the 2015 Model S.
It will produce more lithium ion batteries than all other factories in the world combined...We will also be producing the most advanced cell in the world.
Its lower price tag is thanks largely to cheaper battery packs that can be created by the Gigafactory.
Tesla previously assembled its battery packs with cells made in Japan by Panasonic. But now the companies have teamed up on creating the factory in Nevada.
The latest video follows footage, uncovered by Bloomberg last year, which showed how construction work was progressing.
Musk tweeted at the time that what the drone footage shows is "not the full Gigafactory, it is just the pilot plant (1/4 size)."
Site preparation began in July at an industrial park along US Interstate 80 15 miles east of Sparks, a Reno suburb.
The aim is to produce enough batteries to power 500,000 vehicles a year when it is fully completed and produce a power source that can also be installed in gadgets such as toys and drones.
Production is currently based in Freemont, California, but the plant does not have the capacity to serve the company's future production needs.
The site will also help produce a 'revolutionary' $3,000 battery which Musk claims can run an entire home for eight hours.
Musk introduced the Powerwall device at a press conference in California last year and said the technology could 'change the world'.
Since it unveiled its home battery plans, Tesla says it has been so overwhelmed by initial demand that it is now exploring whether it can expand production at the battery Gigafactory.
While this will be reflected in the quarterly reports that the company submits to GOED, it does not alter the anticipated investment of at least $3.5 billion or the employment of 6,500 once the factory reaches full production.
Last week, Tesla said that it is ahead of its production and construction schedule for the Gigafactory in Reno, Nevada.
Even though Reno has attracted big businesses such as Apple and Amazon, there is concern the city's infrastructure will not be able to cope with the increase in demand.
But it recently emerged that the Nevada battery plant is creating jobs more slowly than first projected, although state officials say it's still making satisfactory progress.
A progress report issued last week by the Nevada Governor's Office of Economic Development said there were 272 people working at the Tesla and Panasonic factories at the end of the year.
That's lower than the 700 jobs initially projected for the end of 2015, according to a September 2014 report available to state lawmakers when they were deciding whether to approve a $1.3 billion tax incentive package for.
"In its application to the state for abatements, the company refined its annual job creation projections to more accurately reflect that the construction of the gigafactory would be completed in phases instead of all at once as the state's economic impact report initially projected," economic development office spokeswoman Jennifer Cooper said in a statement.
"While this will be reflected in the quarterly reports that the company submits to GOED, it does not alter the anticipated investment of at least $3.5 billion or the employment of 6,500 once the factory reaches full production."
Nevada landed the factory after an intense competition between several states.
Economic development officials said the Gigafactory has started shipping out battery packs and powerwalls.
Tesla reported it had invested $374 million in capital in Nevada so far, below the early prediction of $1 billion by the end of 2015.
During the last three months of 2015, there were an average of 894 construction workers at the site each week - 74 per cent of whom were Nevada residents