Don’t be left in the dark – plug your home into a battery

“The issue with existing batteries is … that they suck.” That’s not the kind of quote you’d expect from Elon Musk, a guy who has founded three businesses that depend heavily on battery technology.

Musk’s newest product, the Powerwall, is essentially just a big battery – big enough to power your entire house for several hours. What makes it different is the technology it uses. Instead of the old fashioned lead acid batteries that you’d find in cars or other industrial applications, the Powerwall uses lithium ion cells.  

Lithium ion cells are much more energy dense than older battery technologies. In other words, they hold more electrical energy per gram of weight, which is why they are used in devices like cellphones and laptops where weight is a critical factor. That makes the Powerwall relatively compact for the amount of power it puts out. It weighs a hefty 100kg, but that’s roughly five times less than the equivalent lead acid batteries.   

The standard model has a capacity of 7kW/h. To put that into perspective an average South African household consumes around 15kW/h per day, so one Powerwall would see you through a morning or an evening, but you’d need two (they are designed to be modular) to be totally off the grid for an entire day.   

Tesla’s expertise in lithium ion cells comes from a decade of building electric cars. Its design team also knows how to make products that are as beautiful as they are functional. As such the device is sleeker and more attractive than any other battery on the market, and is designed to be mounted unobtrusively on a wall. This is the Apple Macbook of home batteries.   

And yet Musk is right about batteries – they do still suck. Whereas other electronics double in power and halve in price every 18 months, advances in batteries crawl along and they remain stubbornly expensive. Unlike silicon chips, the physical properties of batteries are simply more difficult to manipulate and optimise. 

Part of the reason batteries remain relatively expensive is that their supply chain is so widely dispersed. Raw materials and components often travel tens of thousands of kilometres, hopping between continents as they move from refiner to component manufacturer to device manufacturer and finally the end user.  Musk and his partners have a risky but brilliant solution to this problem: build the world’s biggest battery factory out in the Nevada desert. In this “Gigafactory” the entire supply chain will be brought under one roof. 

Musk is essentially betting that if he can’t make batteries much better, he can at least make them much cheaper and in far greater quantities. That bet seems to have already paid off – the factory has received so many pre-completion orders that Tesla is already planning to build a second one.

Tesla’s primary market for the Powerwall is households with solar panels, or those planning to install them. This gives the device a powerful synergy with one of Musk’s other businesses – Solar City – that specialises in leasing and installing solar panels on homes. 

But Tesla has probably underestimated the demand for batteries in countries like our own, where electricity supply tends to be irregular. With a starting price of $3 000 the Powerwall is not cheap, but many South Africans would pay far more than that to be insulated from Eskom’s hated load-shedding. And while the Powerwall will only be within the reach of relatively affluent South Africans, this kind of technology might relieve some of the pressure on our national electrical grid.  

Electricity cannot be stored at a large scale – at least not at costs that make such storage economical. When you turn on your kettle a turbine in a power station somewhere spins a tiny bit faster to provide that power. If the peak demand for electricity exceeds supply, the grid can collapse, which is why load shedding is necessary. 

What technologies like Powerwall do is shift demand management from the centre (Eskom) to the edges (households). If even 1% of households could take themselves off the grid and rely on battery power at peak periods, it would make a marked difference.   Combined with solar panels, the Powerwall has the potential to make your home largely energy independent. At the moment, in South Africa, solar panels are even more unaffordable than batteries and so they’re not being installed here anywhere near the rate they are in the United States. 

But if Eskom continues its mismanagement of our electricity grid then the demand for these kinds of technologies, however expensive, will continue to grow. The fact that it’s also better for the planet is an unexpectedly positive side effect of governmental ineptitude. 

It’s wryly amusing that Musk, who was born and bred in Pretoria, may just have accidentally invented a solution to load-shedding while trying to save the planet, and yet most South Africans still haven’t even heard of him. Perhaps when he lands on Mars with his other company, SpaceX, we’ll finally give him a round of applause.

Subscribe to the M&G

These are unprecedented times, and the role of media to tell and record the story of South Africa as it develops is more important than ever.

The Mail & Guardian is a proud news publisher with roots stretching back 35 years, and we’ve survived right from day one thanks to the support of readers who value fiercely independent journalism that is beholden to no-one. To help us continue for another 35 future years with the same proud values, please consider taking out a subscription.

Related stories

Businesses should use alternative energy sources, industry bodies advise

Business associations are urging companies to continue seeking alternative energy sources in light of Eskom’s court judgement which would allow the utility to bump up electricity prices up to 15% from next year April 2021.

Manage urban transformation to avoid infrastructure blockages

It is possible to urbanise without congestion and the attendant ills through emphasis on better institutions, writes Eddie Rakabe

Kicking coal can improve our water supply to all

South Africa’s dependence on the fossil fuel and burning it in power stations uses 5% of water and pollutes even more

A car and a window into the near future

With the introduction of electric — or hydrogen — vehicles like the electric BMW i3, a massive chunk of pollution can be removed from the earth’s atmosphere

The BMW i3 — When electric proves it is the future 

As one of the first cars to make electric vehicles desirable, the i3 has continued refining a car that is a nice place to be. And a brilliant drive

Why Soweto residents do not owe Eskom R18-billion

This debt should be deemed a subsidy, an external cost that the government must bear for inadequate service delivery.

New education policy on gender violence released

Universities and other higher education institutions have to develop ways of preventing or dealing with rape and other damaging behaviour

Cambridge Food Jozini: Pandemic or not, the price-gouging continues

The Competition Commission has fined Cambridge Food Jozini for hiking the price of its maize meal during April

Sekhukhune’s five-year battle for water back in court

The residents of five villages are calling for the district municipal manager to be arrested

Vaccine trial results due in December

If successful, it will then have to be manufactured and distributed

press releases

Loading latest Press Releases…

The best local and international journalism

handpicked and in your inbox every weekday