While wind and solar power have made great strides in recent years, with renewables now accounting for 22% of electric energy generated, the issue that has held them back has been their transience. The sun doesn’t shine at night and the wind doesn’t blow year-round – these are the mantras of all those opposed to the progress of renewables.

Now the renewable power billionaire Elon Musk has just blown away that final defence. Last Thursday in California he introduced to the world his sleek new Powerwall – a wall-mounted energy storage unit that can hold 10 kilowatt hours of electric energy, and deliver it at an average of 2 kilowatts, all for US$3,500.

That translates into an electricity price (taking into account installation costs and inverters) of around US$500 per kWh – less than half current costs, as estimated by Deutsche Bank.

That translates into delivered energy at around 6 cents per kWh for the householder, meaning that a domestic system plus storage would still come out ahead of coal-fired power delivered through the conventional grid.

FK – Does anyone know if this will really work? Will the average consumer be able to afford it? If enough who can afford it buy it will it make grid power too expensive for the rest of us? Is there a time-scale for a switchover? Who will decide that? I think the govt. has true ‘free energy’ systems they’ve acquired from ‘other‘ sources. Allegedly J.P. Morgan stopped Tesla because he didn’t want to sell antennas. What will be the catch for this? There’s always a catch… Yes, I’m cynical. I’ve been paying attention for too long.