Best energy suppliers 2021

·12-min read

Energy bills take a big bite out of household budgets, which is why it’s so important to find the cheapest deal you can without compromising on customer service and overall quality.

Switching energy providers is a straightforward process, but it can be a little daunting, especially if you’ve never done it before. With that in mind, we’ve taken a look at the UK energy market (research undertaken in March 2021) and identified those who we think are the best suppliers.

Our star ratings are determined solely by our editorial team with reference to a range of criteria. See Methodology for more information.

 (green. energy)
(green. energy)

Green. - 4/5 stars

Customer Satisfaction: 5/5

Advice & Support: 2/5

Green Tariffs: Yes

Why we picked it

Green. stands out for its customer service, making it our overall winner. It rarely receives complaints and provides a range of digital tools on its website to help customers manage their energy.


  • Prompt customer service

  • Accurate billing


  • Limited bill information online

  • Sparse information on energy efficiency

See how Green. Energy compares with other providers

 (Octopus Energy)
(Octopus Energy)

Octopus Energy - 4/5 stars

Customer Satisfaction: 4/5

Advice & Support: 3/5

Green Tariffs: Yes

Why we picked it

Octopus Energy provides prompt customer service and accurate billing. It does not charge exit fees on its fixed term tariffs.


  • Excellent customer service

  • High degree of bill accuracy


  • Few digital tools

  • Few green tariffs

See how Octopus Energy compares with other providers

 (EDF Energy)
(EDF Energy)

EDF - 4/5 stars

Customer Satisfaction: 4/5

Advice & Support: 4/5

Green Tariffs: Yes

Why we picked it

EDF performs well with regard to advising on energy efficiency and providing good customer service online. It also benefits from receiving a low number of complaints.


  • Swift, reactive customer service

  • Accurate billing


  • Fixed tariff exit fees

  • Limited energy saving support

See how EDF Energy compares with other providers

 (British Gas)
(British Gas)

British Gas - 4/5 stars

Customer Satisfaction: 3/5

Advice & Support: 4/5

Green Tariffs: Yes

Why we picked it

British Gas has no exit fee on its cheapest fixed tariff contract. It also performs well in the provision online service and boasts an impressive array of digital tools.


  • Rapid handling of emails

  • Good selection of digital tools


  • Long time-waiting on phone

  • Little choice of green tariffs

See how British Gas compares with other providers

 (Scottish Power)
(Scottish Power)

Scottish Power - 4/5 stars

Customer Satisfaction: 3/5

Advice & Support: 3/5

Green Tariffs: Yes

Why we picked it

Scottish Power provides high levels of bill accuracy and scores well for its quality of online customer service. It also offers a wide range of green tariffs.


  • High quality online service

  • Good choice of green tariffs


  • Thin provision of digital tools

  • Imposition of exit fees

See how Scottish Power compares with other providers

Related: Switch & Save Using Our Energy Comparison Service


In our review of 45 energy providers we awarded points in the categories listed below using a five-point scoring system, with additional data from our energy partner, Comparison Technologies. We also used data the firms are required to give to Citizens Advice (this is from the third quarter of 2020, the most recent).

Some companies have fewer than 25,000 customers and so are not obliged to provide the data to Citizens Advice. Where this was the case, firms were awarded a score averaged from the total points gained in that category by all other providers.

We applied the same methodology to companies operating under another company’s licence and whose data is indistinguishable from the parent company.

Bill accuracy & clarity

We referenced the percentage of a firm’s customers who received an accurate bill in the previous year. We also scrutinised firms’ websites, awarding points for help provided in understanding bills.

Customer service (telephone)

We awarded points based on Citizens Advice’s scoring of call-waiting times in seconds.

Customer service (online)

We awarded points based on Citizens Advices’ scoring of the percentage of emails to which companies responded within 2 days. The companies responding to the most emails within 2 days gained the most points.


We awarded points based on Citizens Advice’s scoring of data relating to the number of complaints per 10,000 customers.

Digital tools

We awarded points based on the provision of tools and information designed to help customers manage their energy usage.

Cheapest tariffs

We awarded points to each company based on the cost of their cheapest fixed tariff and the cost of their cheapest standard variable rate tariff.

Green tariffs

We awarded points on the basis of the number of green tariffs offered.

Exit fees

We awarded points based on companies charging low or no exit fees to customers leaving a fixed rate tariff before the end of the term.


We awarded points based on the amount and quality of advice given to customers looking to reduce their energy usage..

Each company’s overall score is based on its performance across all data points. This score has been used to provide an equivalent ES Money rating out of five stars.

Which energy supplier is best for customer satisfaction?

According to our research and our analysis of data from Citizens Advice, the best energy supplier for customer satisfaction is Green. We scored them at 5 out of 5 for this category.

The ‘customer satisfaction’ rating combines a number of elements such as the speed with which the companies we surveyed answered telephone and email queries and the number of complaints they received.

We also looked at the range and quality of the digital tools provided on the companies’ websites to help users manage their energy use and keep their bills as low as possible.

Which is the cheapest energy supplier?

It isn’t possible to point to one energy supplier and describe them as the cheapest for everyone in every situation. That’s because the price you pay for your energy will be determined by a range of factors including how much you use, where you live, what type of dwelling you live in, how many people live in your home and when your home is occupied during the day and night.

This array of considerations means even next-door neighbours could ask for a price quotation from the same firm but get different results back.

You then have to look at other factors, such as whether you want to find the cheapest supplier of all for your home, or whether you want one that is committed to generating or buying green fuels to feed into the national energy networks.

The good news is that, every time you run an energy quote, you’ll be presented with a list of tariff options in price order, so you can see which is cheapest for your circumstances. You can then go straight for the cheapest, or you can work your way down the list until you find a provider and deal that meets your requirements.

Frequently Asked Questions

Why should I switch my energy supplier?

Easy - to save money. Oh, and you might be looking for better customer service. And possibly want a greener energy supply than your current supplier can offer.

You can find out if there’s money to be saved by running an energy quotation. If you’ve never switched supplier or haven’t switched in two years or more, it’s highly likely you’ll be on a standard variable rate ‘default’ tariff. These tend to be the most expensive deals out there, and you’ll almost certainly find a fixed rate tariff that will cost you less.

If you’re on a fixed rate tariff already, it’s still worth checking because new deals come onto the market all the time. Just make sure you don’t incur exit fees if you leave your fixed rate deal early, unless you can save more than they cost by switching.

Running a quote will also give you an idea of what’s available in terms of green energy tariffs, where the energy is produced in an environmentally-friendly manner.

What happens when I switch energy supplier?

Surprisingly little! You get the same gas and electricity through the same pipes and wires, no-one will need to carry out any work at your property, and there will be no interruption to your supply. You’ll simply start getting your (smaller!) bills from a different company. The whole process should take no more than 21 days.

The only exception to this is if you have smart energy meters fitted at the same time as you switch. Every home in the UK will be offered these meters by 2025, and switching supplier can be a good time to have them fitted (provided you want them).

An engineer will come to your home to make the physical meter swap, which should take no more than a couple of hours for both gas and electricity units. He or she may need to shut off the power supply as part of the job.

Can I switch to green energy?

Yes - it’s just a matter of finding an energy tariff that relies on energy produced in a sustainable way, with a minimal carbon footprint. Here we’re talking about wind, solar, wave and other green energy sources.

Having a green tariff doesn’t make any difference to the electricity and gas that comes into your home - you don’t need any special equipment. In fact, you’re getting the same energy as everyone else. But you know that your energy supplier will feed green energy into the National Grid to match what you use. The more people on green tariffs, the greener the grid becomes.

And you don’t need to worry that green energy comes at a premium price. There are many competitive green tariffs on the market that make this a realistic option for most people.

How do I choose the right tariff?

First of all, look at all the different types of tariff available. Each provides different options, so pick the one that suits your needs best. According to Citizens Advice, it’s usually best to choose a ‘fixed’ or ‘capped’ tariff, providing you don’t mind signing a contract for a set period, such as 12 months. The cost of energy then remains fixed for the term of the contract. CA adds that these tariffs are an especially good idea for customers who find it hard to budget.

What is a dual fuel tariff?

A dual fuel tariff means a household receives both its gas and electricity from the same supplier. An arrangement with one, instead of two, suppliers is simpler for the customer in terms of paperwork. It can also work out cheaper. But this is not guaranteed, which is why it’s always worth checking bills and considering swapping suppliers.

What are exit fees?

In most cases, customers who decide to leave a fixed-term gas or electricity contracts before they have run their course can expect to be charged a small penalty for prematurely curtailing the arrangement. Customers on standard variable tariffs tend to pay more for their gas and electricity than those on fixed-term deals but are not charged an exit fee should they decide to call time and switch from their existing supplier to a new one.

What is a standing charge?

A standing charge is a fixed daily amount of money for which the supplier bills the customer, regardless of how much energy a household actually uses in a 24-hour period. It’s added on to bills and applies even when a household is empty for large parts of the year (in holiday homes, for example). The standing charge covers items such as the cost of maintaining networks, keeping homes connected to a network, and meter readings. Both gas and electricity tariffs incur separate standing charges.

What is a pre-payment meter?

These are gas and electricity meters that work on a pay-as-you-go basis. They include key meters, smart card meters and coin-operated meters (although these are increasingly rare). Landlords often install them for tenants in rented accommodation. Pre-payment meters can help a household to budget for its energy use, but they can be inconvenient to use and tend to work out more expensive than standard meters.

Will a smart meter save me money?

Smart meters are the latest version of gas and electricity meters. Part of their aim is to reduce the UK’s carbon footprint. Not only do they measure energy usage, but they also provider the customer with extra information about the gas and electricity being used within a household, such as how much it costs. In theory, smart meters can help a household save money. Energy costs are displayed on the meter’s display screen and the idea is that, by seeing this information, customers are encouraged to reduce their overall consumption.

What if my supplier goes bust?

You’ll be protected by a safety net operated by Ofgem, the energy market regulator.

Ofgem keeps constant watch on energy companies, monitoring their financial strength and investigating any suggestion that they might be at risk of going bust. The firms are also licensed to operate by Ofgem, and as part of that they are required to flag any issues related to their viability.

The safety net guarantees that your energy supply will continue to work, even if your supplier goes bust. Armed with prior knowledge, Ofgem will arrange for another supplier to step in and, literally, keep the lights on (and the heating working). At this point, you should take meter readings and sit tight rather than try to switch to another firm yourself. That can lead to administrative complications as the various parties work to resolve the situation.

But once you receive notification from your new supplier about your new tariff and expected costs, you should run a quotation to see how the new deal stacks up against what else is available. You’re under absolutely no obligation to stick with the new firm, which will facilitate your switch to a different provider. You won’t be charged exit fees.

If you owe money to your supplier and it goes bust, you may still have to pay it back. If the new supplier takes on the old one’s customer debts, you’ll have to pay the new firm. Alternatively, the administrators of the old firm may ask you to repay.

If you’re in credit, your new supplier should pay the money back to you or put your account in credit by the amount concerned. It will get in touch to discuss this with you.

Related: Switch & Save Using Our Energy Comparison Service

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