You will know the name Elon Musk. He's the South African born, 43-year old entrepreneur, engineer, inventor and investor behind such well-known names in the World 2.0 as online money company PayPal,  commercial spaceflight firm SpaceX, electric vehicle business Tesla Motors and  renewable energy provider SolarCity and has envisioned a high-speed transport system called Hyperloop.

But, those many and various exciting 21st Century projects may well pale into significance with the launch of his latest concept - the Powerwall. It is, put simply, a big battery that will hang on the walls of your house, office building or other site (inside or out). It will create an internet-connected smart "microgrid" that would very well bring power supply down to the parochial level. As such, users with alternative local energy generation (solar panels) to go off grid once and for all, sidestepping the national-scale generation of power that still relies on fossil fuels, nuclear or vast hydroelectric power installations.

There are two versions of the Powerwall announced by parent company Tesla Motors. The 10kWh (kilowatt hours) pack, which is optimized for backup applications - filling the role of an uninterrupted power supply, UPS, or backup generator - and a 7kWh unit optimized for daily use. Each can be connected to the conventional electricity grid, but also a site's own solar supply for instance and so provide backup power in the event of a powercut, which many pundits anticipate will become increasingly common thanks to a lack of fuel security, increasing serious storm incidence due to climate change and terrorist attack. Alternatively, the units will allow users with their own renewable, but periodic or intermittent, power source, such as solar, to "extend the environmental and cost benefits of solar into the night when sunlight is unavailable," as Tesla puts it.

If you have large premises you will need more units, of course. Speaking of which, the scalable version of Powerwall is known as Powerpack and could be used by large businesses, industry applications, even public utilities to interconnect 100 kWh units as a block of five all the way up to a 10 mWh facility and even beyond.

It sounds wonderful, a brave new world of personal power for our homes and workplaces. So, what's in the box? Well, it's all rather disappointing to be honest. Although it has the bells and whistles of being internet connected, "smart", having its own solar inverter and being self cooling with its liquid thermal control system, it is at its heart just another lithium-ion battery pack, with all the well-known foibles of those systems, I suspect.

As the news announcements spread across the US, while I slept last night, and I was confronted with a news stream almost full of regurgitations of the Powerwall press release and pronouncements, I was rather hoping to see that the system had at its core some wondrous new materials science that would extend battery longevity way beyond those we experience with lithium batteries. Everyone who hangs on to a laptop or mobile phone for more than a couple of years knows only too well how Li batteries became less than fully chargeable after about 18 months and barely take a trickle by age 3. The issue arises more quickly if batteries are allowed to fully discharge as is often the case with portable gadgets like laptops and phones.

Maybe Powerwall's smart optimization systems have somehow subverted the inevitable chemical degradation by keeping the cycles going and avoiding complete discharge. Perhaps users will see similar lifespan to that offered by the batteries in Tesla's electric vehicles. The lifespan is typically about eight years, which equates to about 200 000 kilometers of driving for the 85 kWh version of the car battery. Is eight years long enough for economic payback for a Powerwall system at home? Tesla is guaranteeing the units for 10 years. Tesla Motors is planning to open a battery factory in Nevada, USA, in 2017 and SolarCity is piloting the 10 kWh packs in 500 homes in California.

I can see that the media and company hype surrounding Powerwall will drive a lot of early adopter sales, especially for premises that already have access to a solar installation and for places where power outages are common and costly. The emergence of cheaper rivals in the next few years could help spread the parochial power message. It is definitely a step in the right direction to sustainability.

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".