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Batteries For Your Home - Do They Stack Up?

11/09/2017 13:33 BST | Updated 11/09/2017 13:33 BST

Renewable energy is clean, popular, and already cost competitive with old fashioned fossil and nuclear technologies.

But every form of energy civilisation has harnessed has had its Achilles' heel. For renewables, it's intermittency: wind turbines and solar PV panels don't always produce power when we need it, and sometimes produce power when we don't.

Thankfully, domestic batteries - particularly lithium ion batteries of the kind that power our smartphones and laptops - are emerging as a promising solution to this challenge.

Today, electricity storage is most common in households with some form of home generation technology (most commonly PV panels on our rooftops).

These homes currently get paid under the government's Feed-In Tariff scheme for the electricity they generate, regardless of whether they use it or spill it to the grid. Unsurprisingly, it's in their interests for their energy demands to be met by the free power they generate, rather than with additional costly power they buy from the grid.

But PV panels generate most during the middle of the day when many of us are out of the house at work. A battery could store this power for us, to be used when we get home in the evening. And batteries have the bonus feature of providing backup power in the event of a power cut.

This new battery technology is exciting, not least because it will be vital to increase the deployment of renewable power generation.

But that doesn't mean domestic energy storage is ready for the majority of us, yet.

Domestic batteries are still in the 'early adopter' phase, appealing to those that are motivated by the love of new technology, or perhaps a desire to live "off-grid". However, most people will make the decision to install a battery based on the economics - and today they don't really stack up.

Domestic batteries are still expensive, particularly when you include the installation costs and all the related controlling equipment needed. Batteries also degrade every time you charge and discharge them.

The systems on the market tend to come with a ten-year guarantee, which gives you a sense of their manufacturers' view of their life-expectancy - and the timescale you would have to break even on your investment. Based on today's economics, most households never would.

Incidentally, the picture for business energy users can look quite different and, in some cases, businesses are already reaping rewards from battery installations. But, what needs to change before the economics of home batteries stack up for us all?

Firstly, the kit needs to be cheaper. Costs are falling all the time and the speed of the cost reduction has outstripped most predictions that were made.

Secondly, the domestic market needs to mature. There are good and some bad systems out there and, similarly, good and bad installers. The weak points in the systems we've seen tend not to be the batteries themselves, but the control systems that sit between the battery and our energy-using appliances.

Thirdly, government policy needs to change to better recognise and reward the benefits that domestic batteries offer beyond the houses they're installed in - to the grid, the environment, and other energy users. For example, by reducing energy demand at peak times, domestic storage could reduce the need for new power stations, saving us all money.

Lastly, we need more sophisticated home energy tariffs, with pricing that better rewards customers for shifting demand away from peak periods. This vision depends on the successful rollout of smart meters.

Domestic batteries have fantastic potential, but there are some critical pieces of the jigsaw to fall into place first. When the time is right, battery storage will fundamentally change the way we use energy in our homes.