Renewable electricity in the UK: is it always clean — or does timing matter?
If you’re on a green tariff, you probably think your electricity is always clean. In some cases, that’s true — but it’s not always the full picture.
When a tariff is labelled “100% renewable”, it usually means your supplier buys the same amount of renewable electricity as you use — but not necessarily at the same time. So if you use 10 units of electricity, they buy 10 units from wind, solar, or other renewable sources. But that doesn’t mean your home is being powered by renewables at every moment of the day.
This is because electricity doesn’t come from one specific source directly to your home. It all flows through the same grid, and the mix of electricity you use is the same as your neighbours’ — even if they’re not on a 100% renewable tariff.
The mix of energy sources in the grid also changes constantly. When it’s sunny or windy, a larger share comes from renewables. In the evening, when most people are at home — cooking, heating their homes, and plugging things in, demand rises quickly. To meet that extra demand, the system often brings in gas power stations, which increases emissions.
Why timing of use matters
- Even on a green tariff, the timing of your usage still affects overall emissions
- Using electricity during busy evening hours often means more fossil fuels are being used at that moment
- Shifting usage slightly can help the grid make better use of available renewable energy
What you can do
- Stick with your green tariff — it still supports renewable energy overall
- Check when electricity is cleaner in your area using EnergyTrace (you can see it in real time and ahead of time)
- Where it’s easy, run things like laundry, dishwashers, or EV charging when the grid is cleaner — for example, during the day or later at night
A green tariff helps in the bigger picture, but what you do day to day still matters.
Small shifts, across many households, can add up to a real difference.
Next, we’ll look at energy suppliers that can actually reward you for shifting your usage at certain times.
Photo by Andreas Gücklhorn on Unsplash
Photo by Zoshua Colah on Unsplash