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Ecotricity Explains: What is a dunkelflaute?

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27 Jan 2025

What happens when the wind isn’t blowing, and the sun isn’t shining? We’re often asked this question, and our answer is an easy one: we need the smart grid. It allows us to see how much energy is being used and importantly manage demand. 

Put simply, the smart grid system is real life energy balance for supply and demand and then batteries fill the gap. 

In Germany they have a word of their own for this kind of event – dunkelflaute

ecotricity explains dunkelflaute sun wind
What does dunkelflaute mean? 

It’s a mix of ‘dunkelheit’, which means darkness, and ‘windflaute’, which means a lull in wind –  this rather obviously affect renewable energy generation.  

Whilst solar panels can still generate electricity on cloudy, wintery days, they won’t generate as much as they would in summer, or at night which is a daily event. Windmills work the same – their output relies on the strength of the wind blowing at any given time.  

The good news is wind and solar are setting new records almost month on month as we power Labours’ green target of 100% renewable energy on the grid – renewables are on the rise.  

But, and this one is a but - Balancing the grid is an important job. It is not more of an important job than in the past, just a different job and for that we have the smart grid concept in which smart meters play a vital role supported with grid scale energy storage of which batteries are the leading technology (but there are many different ways coming soon too). 

So there is another way – the smart grid.  

ecotricity explains dunkelflaute battery
How does grid scale battery storage work? 

Battery energy storage systems are far bigger and far more advanced than the rechargeable batteries we use in our smartphones and laptops. Nonetheless, when it comes to the fundamentals, they’re very similar indeed. Power goes in, it’s stored in the battery, then flows out again when needed. Grid scale batteries use energy management systems to coordinate energy storage with energy production, deciding when to increase the reserve or release energy to the National Grid. In this way, green energy generated at times of low consumption is stored for use when demand peaks. Up until now, these peaks have been filled in by firing up extra generation capacity in a fossil fuel. As more battery storage is installed to match continued increases in green generation, there will be less and less need for fossil power. Batteries can also react at a speed that no rotating mechanical machine can match – making them a better answer to power and voltage needs. 

ecotricity explains dunkelflaute pv roof
So, how can you help? 

If you haven't already got one, get a smart meter, see if you can install solar panels or batteries or other green tech in your property. Not only will this lower your bills by enabling you to use the energy you’re generating, but you’ll also be lessening the demand on the national grid.  

You can play your part in the smart grid revolution. With a battery it will also be a way to save money – and we have some exciting developments coming down the road on this. We will keep you updated. 

For now, find out more about our upcoming Smart Export Tariff

The simplest thing you can do is switch your home energy supply to Ecotricity. We use the profits from our customers’ bills to build new sources of green energy ourselves, rather than just use up what's already out there. We call this turning bills into mills. 

Plus, we’re not-for-dividend – your money is being used to green up Britain.

Ready to start turning your bills into mills?

Switch to Ecotricity and we’ll use your bill money to build new sources of renewable energy and build a greener Britain.

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Ecotricity Explains: What is a dunkelflaute?

What happens when the wind isn’t blowing, and the sun isn’t shining? We’re often asked this question, and our answer is an easy one: we need the smart grid. It allows us to see how much energy is being used and importantly manage demand.

More