Is it really worthwhile getting a battery to store electricity? I bought a battery, but I have my doubts. The battery cost €3,000. Only stores five units. And the battery has a finite lifespan.- Peter Casey, Co Dublin
I think it’s a bit of a split decision right now on whether or not a storage battery is a good solution, not least because if you have an electric car, then you already have a storage battery, just one with wheels.
However, we need to see these things in the round, so here goes.
A storage battery, even a relatively small 5kWh one, can be a hugely useful power buffer for your house, not only in terms of providing you with electricity if there is a power cut (and big storms are becoming far more common ...) but it can also allow you to charge it up on cheap night rate electricity, and then use its energy at peak cost times, such as around dinner time, which can save you a packet. Use a storage battery cleverly, and you could claw back that €3,000 in pretty short order.
RM Block
Indeed, we know of people who, with a combination of solar panels, storage battery, and an EV (and don’t forget there are grants available to defray the cost of a lot of this stuff) have cut their electricity bills to almost zero.
That cutting includes a good deal of exporting energy back to the grid, as you suggest, but that doesn’t have to be an either/or calculation when it comes to the storage battery.
If you have solar panels as well – and solar is the really crucial element of all of this, even in damp, dank, rainy Ireland – then you can potentially charge up your storage battery and your electric car at night on cheap rate electricity, which is not only good for you, but also good for everyone as you’re basically acting as a sponge for night-time wind-generated power which would otherwise go to waste.
Then, during the day, you can sell your solar-generated power – the majority of which will probably be generated when you’re all out at work and school – to the grid, offsetting your investment costs.
I wouldn’t assume that the battery has a “finite” lifespan either. The general rule of thumb for storage battery life expectancy is up to 15 years, possibly even 20.
Given the robustness we’re seeing when it comes to electric car batteries – which have far higher and faster charging and discharging demands – I wouldn’t be surprised if a home wall battery, kept properly maintained, could last even longer than that.
By then, there will also be a value in the battery’s raw materials, the lithium, manganese, and cobalt, which are all recyclable, and which will be in high demand for recycling into new batteries. That will give you a trade-in value for that battery against any replacement.
However, we do need to come back to the question of using your electric car as a storage battery, and that’s certainly not a bad idea.
Even a relatively cheap EV will have a battery approaching 50kWh capacity, which is enough to keep your house running for several days if you have an EV with vehicle-to-grid functionality – and almost all do at this stage.
However, there’s a limitation, and that’s the fact that most EVs can only transmit their battery energy at around 3.6kW, which isn’t really enough to run your house at full capacity. It’ll keep things like fridges, lights, and TVs ticking over in a power cut, but power showers and fan-assisted ovens will be off-limits. True, some EVs can manage up to 7.4kW but even that won’t power your house at full demand.
This is where the storage battery can come in very handy, as it will be designed to act as an uninterrupted power source if there’s a total blackout in your area. It also means that you’re not then draining power from your EV battery, which you might well need, at a time when recharging might be tricky depending on how big a power cut we’re talking about.
Equally, in the future, when the majority of power is generated from renewable sources, storage batteries will be vital for grid-balancing and provision of continuous power, so why not get in on the ground floor, so to speak?
I seem to have talked myself into the usefulness of a storage battery anyway, but of course, the best thing is to sit down, do your homework, talk to suppliers and installers, and your energy provider, and find the best solution for yourself.
