Your cheap rate times haven't changed - we just need to move more off-peak. Use the same amount of water, just make it cleaner and cheaper. 

Use, run and charge electrical appliances off peak. 

How do I change the timers on my hot water cylinder?

What is everyone else doing?

We ran a big customer survey in 2025 to try and help answer this question for you.

• We discovered that more than half of all homes in Guernsey said they rely on electricity for year-round water heating. Even if you use gas or oil to heat your home in the winter, many of us switch to electric immersion heaters during the summer months for water heating.
• 80% said the issue of climate change was somewhat to extremely important to them personally
• Around six in ten islanders said they heat their water overnight (between 11pm and 5am) to help reduce cost and carbon
• Nearly nine out of ten also said they run some other electrical appliances overnight for the same reason  

Survey statistics correct as of September 2025 

What can you do next?

Overnight between 11pm and 5am is the best time to use electricity here in Guernsey, but we know that isn't always practical. 

Best time

• Set the delay timers to use, run or charge electricals overnight between 11pm and 5am.
• Cheapest and cleanest time to use electricity in Guernsey 

Second best time

• Between 10am and 4pm, as less people are using electricity. Make sure to use your two hour daytime cheap rate periods which you'll find on the back of your electricity bill. 
• Cheaper and cleaner than using electricity at other times of day (generally the worst times are 5am to 10am, and particularly 5pm to 11pm). 

If you care about our local environment, then this part is for you. 

There is a simple way to help cut our island's carbon emissions - just set your water to heat between 11pm and 5am.

Timers are a secret weapon that help protect our local environment. 

Did you know? Heating water uses a huge amount of electricity. If you heat water during the day, in winter you'll need to rely on fossil-fuels to keep it hot. 

It’s all about when we use our energy.

• Overnight is when Guernsey uses the most clean energy as low-carbon electricity is imported through our subsea cable from the European grid. 

• During the day, the island relies on local fossil-fuel generators to keep up with demand during winter. By heating water at night, you'll help reduce local air pollution. 

• Bonus - if lots of people do the same, it'll help reduce future tariff rises as it costs a huge amount of money to meet islander's increasing electricity demand using the power station during 'peak' times.

How to change your timer

Other electrical appliances.

Electric heating

If you use electric central heating, or if you ever use small plug-in electric heaters, these will likely demand the most power. But realistically, you can't move heating overnight, unless you use Off-Peak Storage Heating which banks low-cost, low-carbon electricity overnight. 

Home appliances

Water heating comes next in terms of placing a big demand on your electricity. But if you'd like to save more and reduce carbon emissions even further, why not consider moving some of your other electrical appliances off-peak too. 

The best appliances to use 'off peak' are those with in-built time delays, such as:

1. Hot water cylinders
2. Electric vehicle charging
3. Dishwashers
4. Washing machines
5. Tumble dryers

Safety First

These are really important steps that can't be ignored. If you're in any doubt, please only change the timers on your hot water cylinders. 

What is 'Peak Demand'?

Peak demand is the time when consumer demand for electricity is at its highest.

Usually around breakfast, lunch and dinner, peaks exist simply because more people are indoors when its cold, dark and using electrical equipment to power their lives.

In Guernsey, we import around 60MW of low-carbon energy from the European grid. But when customers demand more than 60MW of electricity, this must be topped up using fossil-fuel generators at the Vale Power Station. 

Using electricity during peak times will increase Guernsey's greenhouse gas emissions - especially during the colder, darker months. Plus, the wear and tear on equipment will need paying for too. 

Less pressure on the power station means: 

• Less local air pollution
• Less pricey maintenance
• Less repair

Want some help reducing your reliance on fossil-fuels? Find out more about our services designed to help islanders get energy smart. 

Home Energy Audits

Here's an example 

In January 2024, Guernsey reached its highest demand at 94.2MW in response to cold winter weather that week. 

As mentioned in the news, Jon Sexton, Head of Engineering and Design at Guernsey Electricity, said: “The maximum energy we can import through the subsea cable is 60MW, which means that generators at the Vale Power Station were required to meet the additional demand."

This meant we needed fossil-fuels at the power station to meet the extra demand - for ease of reference, the 60MW importation capacity has been marked up below.

It's only natural to use more electricity during colder, darker months - meaning it's even more important to be mindful of the electricity we're using and move what we can to the cleaner, off-peak periods between 11pm and 5am.

How can I use low-carbon electricity? 

Where possible, move as much electricity use as you can to between 11pm and 5am.

The best appliances to use 'off peak' are those with in-built time delays, such as:

1. Hot water cylinders
2. Electric vehicle charging
3. Dishwashers
4. Washing machines
5. Tumble dryers

Don’t have built-in timers?

Hold off on using these appliances around breakfast and dinner until later in the evening. Any time from 9pm works well, provided this is on or before your Super Economy 12 low-rate time band.

Find your specific time bands on the back of your electricity bill 

Here’s an example:

A quick one hour washing machine cycle at 6pm or 7pm, especially during winter, means using fossil-fuels to generate the power. 

In other words, you’re cleaning your clothes using fossil-fuels 

But if you set a time delay to start much later, you could get your clothes clean using cheaper, low-carbon energy, as electricity demand is so low overnight. 

Cleaner energy for cleaner clothes. 

Plus, using a longer 'EcoMode' should help save you money too as it actually uses less electricity and less water. Particularly if you’re on the Super Economy 12 tariff which uses electricity that's over 50% cheaper than earlier in the day. Look after those pennies, as over time it all adds up!

How can I spend less money? 

Bad habits cost you money, and when it comes to electricity there are so many ways people can reduce their bills. Why pay for electricity you aren't using? 

First, a few things to check. 

1. Are you on the Super Economy 12 Tariff? If not, sign up today 
2. What are your low-rate times? If you're not sure, check the back of your electricity statement
3. Do your appliances have time delays? If not, try using a smart plug for plug-in appliances

Once you're all set with your low-rate times, simply use your electrical appliances as much as possible when it's over 50% cheaper to use. It's a win-win for your wallet and the planet. 

Or if you'd prefer someone to visit your home and help save energy for you, why not book in a home visit with one of our Energy Savers. 

Home Energy Saving Audit 

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