How to choose the best energy supplier

Many energy firms are welcoming new customers again after a long pause. Use our tips to find the best energy firm for you.

There are more than 20 energy firms to choose from at the moment. This is down from more than 50 at the end of 2020.

It's now possible to switch providers again and we've started to find fixed deals that can save around £200 compared to the price cap variable rates. 

Switching can save some money, and our research reveals big differences between customers' experiences with the best and worst energy providers. 

Keep scrolling for advice on how to find the best energy firm for you. Or see the best energy companies for 2025.

Alternatively, use our independent service to compare gas and electricity prices.

Octopus, British Gas, Ovo and other big energy companies

In January 2025, new brand Octopus Energy announced that it is now the biggest energy supplier in the UK, serving 7.3m customers - or 1 in 4 households.

Four longstanding energy firms - British Gas, EDF Energy, E.on Next and Scottish Power - make up a large portion of the rest of the energy market. Ovo has also grown considerably, taking on SSE's customers. 

Biggest isn't necessarily best, according to our research. While Octopus Energy is a Which? Recommended Provider again in 2025, several other big-name brands languish near the bottom of our results table.

Our energy company results give you a unique insight into what your fellow customers really think of their energy suppliers. Plus, we've gone behind-the-scenes to check how well their practices are in the best interests of customers.

Use the results of our lastest energy survey, plus our expert advice, to cut through the marketing jargon and money-saving claims to find the best energy suppliers.

Looking for energy firms in Northern Ireland? Head to our guide to Northern Ireland electricity and gas companies.

Should you choose a renewable energy company?

Several energy companies, and more tariffs, are branded as ‘green’. But there’s no set definition of what ‘green’ means, so it’s worth checking before you sign up to make sure you’re getting what you expect.

So we asked energy companies for information on a range of sustainability criteria in August 2023. Then we awarded them points based on their responses and information published on their websites. 

As a result, we named 100Green, Ecotricity, Good Energy and Octopus Energy Eco Providers for 2023. Find out more in our guide: Small energy companies A-Z.

Our scoring looked at:

• Generating renewable power
• Buying and selling renewable power
• Carbon intense power
• Green gas
• Time of use and Smart Export Guarantee tariffs
• Low carbon installations
• Transparency and clarity.

Find out more about our scoring for the Eco Providers for energy 2024.

Ecotricity was the first company to offer ‘green electricity’ made from renewable sources – it sits alongside Good Energy as one of the most longstanding renewable energy companies.

Both firms only sell tariffs backed by 100% renewable electricity and supply a proportion of ‘green gas’ (from biomethane). Ecotricity uses money from its customers' bills to fund new renewable generation. Good Energy, meanwhile, buys its electricity from more than 1,700 independent renewable generators and 100Green sells 100% green gas.

Other energy suppliers selling tariffs with 100% renewable electricity include E.on Next, Octopus Energy, Outfox the Market, Ovo Energy and So Energy. 

You'll also find other energy firms selling 'zero carbon' tariffs. These include EDF Energy. This usually means their electricity comes from either renewables or nuclear power. 

Additionally, some suppliers sell a proportion of green gas (usually from biomethane) and invest in carbon reduction or carbon offset schemes for their gas tariffs.

Find out more with our guide: differences between green energy suppliers.

Consider online energy tools and smart home technology

Some newer energy firms claim to be digitally focused and pride themselves on a slick online service, apps and user-friendly websites.

Boost, E and Utilita's customers with smart prepayment meters can top up via their apps. 

Several firms, including Ovo, Scottish Power and Utilita, show customers how their electricity use and spend is split between different types of home appliances in their apps or online account.

Smart meters

All energy firms are installing smart meters. These replace your existing gas and electricity meters and use a wireless data network to send your usage figures straight to your energy supplier.

Smart meters usually come with an in-home digital display. The makes and models of these vary between suppliers but they have the same basic functionality of showing you your energy use and spend in near real-time.

A few monitors are now wi-fi-enabled, including the latest ones from Ovo and Utilita. This means meter readings can be collected in real-time and it's easier to update your monitor or diagnose any problems with it.

Octopus Energy is testing its 'Octopus Home Mini' which uses wi-fi to transmit your usage and costs to your app and online account in a few seconds.

Most companies also let you see your smart meter data in an app or online account though their exact functions vary. 

Want to find out more about smart gas meters and smart electricity meters? Visit our expert guide: What is a smart meter?.

Energy apps

Most energy suppliers offer their own mobile apps through which you can monitor your energy usage.

These apps typically include the following features:

• show historical usage, usually split by fuel and day/week/month depending on how often your smart meter sends data
• let you view your bills
• view account details and payment information
• send meter readings
• prepayment meter top-up

Smart home products

Plenty of suppliers are selling smart-home products too, or including them free when you sign up to certain tariffs. They include:

• British Gas – sells smart products from its Hive brands, including smart thermostats, smart plugs and smart light bulbs.
• Ovo Energy – currently offers the Tado smart thermostat.
• Scottish Power – also sells Tado smart thermostats as well as smart radiator thermostats, which let you control the heat in each room separately, and smart hot water controls.  

To learn more about the power of smart home technology, check our guides to outdoor security cameras, indoor security cameras, smart thermostats and smart radiator valves.

Energy and broadband bundles

Some firms bundle multiple home services together in one monthly bill. Utility Warehouse was the first firm to do this.

Utility Warehouse provides energy, broadband, mobile and home insurance in one package. The firm says this allows customers to 'get on with the things that really matter in life.' During our latest energy supplier survey, we heard from a number of Utility Warehouse customers who appreciated the system.

Find out what customers think of Utility Warehouse broadband.

Boiler cover and insurance

Several larger energy companies sell boiler cover that often comes with call-out repair services if yours breaks. Often they're a partnership with an insurance provider:

• British Gas's HomeCare packages include boiler servicing and repairs, depending on the package. It also sells appliance and home electrics cover.
• EDF Energy sells boiler maintenance and insurance plans from Domestic & General.
• Eon Next sells boiler cover, central heating cover, electrics and plumbing cover from HomeServe.
• Ovo Energy's boiler cover includes servicing and breakdowns.
• Scottish Power sells boiler cover from Domestic & General.

To save money and avoid being charged over the odds, explore our guide to how to choose the best boiler cover.

Innovative energy tariffs

The majority of tariffs are structured as:

• daily standing charge
• a set rate for each unit of energy you use (unit rate). 

The charges and rates are different for gas and electricity. But there are different types of tariffs if you look for them, many enabled by smart meters.

Smart tariffs 

These require you to have a smart meter installed. Often they give lower prices for electricity used at specific times of day. For example:

• British Gas' Half Price Sundays provide customers with half-price electricity between 11am and 4pm on Sundays.
• Octopus Energy's Intelligent Octopus tariff has six hours of cheaper electricity overnight. Its Agile Octopus tariff tracks half-hourly wholesale prices and updates its rates daily. 

The government expects smart tariffs to become more widespread as smart meters are further rolled out, more people have electric vehicles and electricity demand increases.

Electric Vehicle tariffs

Most EV tariffs require you to have a smart meter, as well as an electric vehicle charger. Customers can get cheaper electricity for a number of hours – usually overnight – to help charge their car's battery for less.

A growing selection of energy suppliers sell EV tariffs, including British Gas, EDF Energy, Octopus Energy and Ovo Energy. 

Read more about different types of energy tariffs explained. 

Pay-as-you-go energy

Several energy suppliers focus on customers with prepayment energy meters, including E and Utilita. Boost Power customers have been moved into the care of its parent company Ovo Energy.

If you have a smart prepayment meter you can top-up using your provider's app, your online account or by phone.

If you have a PAYG energy meter, or are considering one, read our advice guide: Is a prepayment energy meter right for you?.