Power - when it’s needed

Annual savings of €102 million: that’s the amount of money that consumers in the Republic of Ireland and Northern Ireland could be saving if battery energy storage systems (BESS, or home storage batteries to you and I) really start to take off.

According to the ESB, Ireland currently has around 300 megawatts of battery storage hooked up.

A report by Energy Storage Ireland, which calculated that €102 million savings figure, estimates that those savings really start to stack up once two gigawatts of energy storage are connected to the grid.

What’s the big benefit of battery storage? Where home electricity is concerned, having a battery means you can charge it up overnight, at the cheapest possible rate, and then use that stored energy at peak-use times, dramatically cutting your electricity bill.

Better yet, in a global sense, that putative two gigawatts of total storage could mean an 11 per cent cut in Ireland’s electricity generation emissions, not least because storage batteries can be charged from solar panels on your roof and can soak up wind energy generated at night which would otherwise go to waste.

Just make sure you go for a lithium-iron phosphate (LFP) battery — not only are these more affordable, but their chemical makeup is also more stable and more reliable over time.

Batteries can also be even more eco-friendly than you’d think, as they are often “second life” batteries, recycled from previous use in electric cars.

What else should you consider before installing a home storage battery?

According to the Sustainable Energy Authority of Ireland: “Systems should be sized appropriately for a home’s energy needs. Designing a solar panel setup and/or battery system to optimise the use of that electricity, what is important to remember is that larger is not always better.

“General rule of thumb is to look at how much electricity you use in the evening, eg from 4pm–10pm. You don’t necessarily need to size it to meet all of the demand in this period, but it’s a useful rule of thumb for the typical energy used.

“Most homes have smart meters now, so how much you use in that timeframe on average across the year is readily accessible. Most modern batteries are modular, so you can start small and build capacity over time if that is needed.”

Batteries will generally be sized at 5kWh, 7.5kWh, or 10kWh capacities – a typical Irish household gets through about 11kWh in an average day.

So why not have a bigger battery? Two reasons, really. One, each kWh adds to the up-front expense, and you may not need to use all of the extra capacity all the time; and two, the growth of electric cars with vehicle-to-load (V2L) tech means that the massive battery in the EV you might be buying soon could eventually act as a much more flexible home energy storage solution.