The best green energy suppliers in 2021: how to switch to renewable energy

Switch to one of the best green energy suppliers and you'll reduce your carbon footprint - and maybe your bills too

Included in this guide:

Switching to a green energy supplier has never been easier. In the UK we have more choices than ever before, as the market moves towards embracing renewable energy. In fact, these days it isn’t hard to find an energy supplier that can provide 100% green electricity. Most of the Big Six energy companies – British Gas, EDF Energy, E.ON, Npower, Scottish Power, and SSE* – have tariffs that offer this. 

However, if you want green gas too – or at least a certain portion of it – you’ll have to turn to one of the smaller energy suppliers. And that's where we can help. In this guide, we'll show you the very best green energy suppliers in the UK.

The good news is that green energy doesn’t have to cost you more. Our ongoing energy comparison research continually shows that some of the cheapest energy suppliers are green energy companies. 

Switching energy supplier is easy, if you decide to go with one of the best green energy suppliers below. It takes less than two minutes to get a quote – all you need to do is provide your postcode (because energy prices differ across the country) and a few details about the property you live in, such as how many bedrooms there are. Then simply choose the best energy deal for you. You can switch straight away, if you like. 

The best green energy supplier in the UK

The best green energy supplier in the UK right now is Bulb. This renewable energy company has strong green credentials, providing 100% green electricity and 10% green gas (the rest is offset through carbon reduction projects, making it 100% carbon neutral). It also has just one tariff, which keeps things straightforward. 

Bulb gets consistently good reviews from customers too. It’s chalked up an impressive 4.8 out of 5 stars on Trustpilot, from 44,000 reviews (June 2020). Plus, if you refer a friend, you’ll get £50 each.

The right green energy supplier for you will of course depend on your personal preferences and budget. Bear in mind, too, that just because you've signed up to a green energy supplier, there's no guarantee – and no way of ensuring – that what comes out of the National Grid into your home is actually green. However, the energy that goes back in to replace what you've used will be green. 

Whether you're looking for the greenest energy supplier, cheapest green energy supplier, best customer service or more, here's everything you need to know to make the switch to green energy.

The best green energy suppliers in the UK right now

best green energy supplier: Bulb

(Image credit: Bulb)

1. Bulb

The best green energy supplier in the UK – and if you refer a friend, you'll both get £50

Energy provider: Bulb
Green electricity: 100%
Green gas: 10%
Renewable sources: hydro (9%), solar (40%), wind (51%)
Carbon offsetting: Yes
Exit fee: None
Reasons to buy
+Only one tariff to choose from+10% green gas+£2 donated to charity when you switch
Reasons to avoid
-No fixed tariff, so prices can go up or down

We think Bulb is the best green energy supplier in the UK, with excellent green credentials, fair prices and first-class customer service. Launched in 2015, it’s the fastest-growing green energy provider in the country, now supplying over 1.4 million homes. 

That's in no small part down to its affordability: Bulb generally sits at the cheaper end of the UK energy market. The exact price you pay depends on where you live, as is the case with all energy companies. However, independent energy switching site Energy Helpline found Bulb to be on average 17% cheaper than standard deals from the Big Six.

Bulb buys its energy from independent generators, so it's able to guarantee its electricity is 100% green (it’s produced from hydropower, wind and solar). It also supplies 10% green gas – that's around average for a green energy supplier – which comes from renewable sources such as food and farm waste. Bulb then offsets the rest of the gas it supplies by supporting carbon reduction projects around the world, making its gas 100% carbon neutral. 

Happily, Bulb has just one tariff, which is simple to understand. It’s variable, which the company says makes pricing fair because any drops in the wholesale price of energy will be passed on to you. But like any variable tariff, bear in mind that prices can go up too. Finally, it’s worth noting that Bulb doesn’t charge an exit fee if you choose to switch energy provider. 

Bulb isn't the greenest energy supplier in the UK – that crown goes to Green Energy UK, below, which delivers 100 green gas. Bulb is cheaper than Green Energy UK, though. And it's beloved by customers, averaging an impressive 4.8 out of 5 stars on consumer review site Trustpilot, from 44,000 reviews. If that’s not enough, when you switch they’ll donate £2 to their charity, The Bulb Foundation. Plus, if you recommend a friend, you’ll both get £50. 

best green energy supplier: Octopus Energy

(Image credit: Octopus Energy)

2. Octopus Energy

The best green energy supplier for customer service, and they’ll also reward you and a friend with £50 each for switching

Energy provider: Octopus Energy
Green electricity: 100%
Green gas: 0% - but 100% carbon offset
Renewable sources: Anaerobic digestion, solar, wind, hydro
Carbon offsetting: Yes
Exit fee: £30 per fuel
Reasons to buy
+Award-winning customer service+£50 when you switch
Reasons to avoid
-Too many tariffs to choose from for some

Octopus Energy is the best green energy supplier for customer service – and for the second year running, it's a Which? Recommended Provider too. As well as winning awards for customer satisfaction, 97% of the company's 22,000 reviews on Trustpilot are rated good or excellent. That's very rare for an energy company, and means Octopus has the maximum five star rating on Trustpilot. 

Octopus has strong green credentials, too. When you choose its Super-Green tariff, Octopus will supply 100% renewable electricity, and the provider promises to ensure that any carbon involved in the production of your gas will be offset. It does this by partnering with Brighton-based charity Renewable World, which specialises in carbon-reduction projects in the developing world. 

best green energy supplier: green energy UK

(Image credit: Green Energy UK)

3. Green Energy UK

The greenest energy supplier in the UK, and the only one to have 100% green gas

Energy provider: Green Energy UK
Green electricity: 100%
Green gas: 100%
Renewable sources: hydro, solar, wind,
Carbon offsetting: No (not needed)
Exit fee: None
Reasons to buy
+100% green gas+100% green electricity
Reasons to avoid
-Expensive-Some concerning reviews online

Green Energy UK is the only supplier to offer 100% green gas as well as green electricity, making it the only true green energy supplier in the UK. You’ll have to pay more for these green credentials though, because Green Energy UK is exempt from the Ofgem price cap. In fact, the provider was 38% more expensive when we did a price comparison of all the suppliers mentioned in this guide. 

We signed up to Green Energy UK and found the switch to be very easy, with plenty of information from the company. We've received very good customer service since, and billing has been accurate. The company averages 4.5 out of 5 stars on Trustpilot, albeit over a smaller review pool of around 800. 

If you're looking for a truly green choice, Green Energy UK is it. However, just make sure the company has the correct meter readings: if your energy use has been estimated incorrectly and you're hit with a 'catch-up' bill, you'll know about it.

Best green energy supplier: Outfox the Market

(Image credit: Outfox The Market)

4. Outfox The Market

The cheapest green energy supplier, but questionable customer service

Energy provider: Outfox the Market
Green electricity: 100%
Green gas: 0%
Renewable sources: Wind
Carbon offsetting: No
Exit fee: None
Reasons to buy
+The cheapest in our price comparison+Live chat customer service+100% green electricity
Reasons to avoid
-Concerning reviews online

Outfox the Market is the cheapest green energy supplier available. The company claims to pass on the best prices to customers with a no frills approach, but the number of negative reviews online is concerning (21% of nearly 26,000  Trust Pilot reviews are 'poor' or 'terrible'). Recently, Outfox the Market scrapped its old membership charge in favour of the typical standing charge like all the other suppliers. They may be the cheapest, but it’s worth noting that the best supplier, Bulb, is only a little more expensive and is far more established with much better customer service.

Best green energy supplier: npower

(Image credit: npower)

5. Npower

The best option for green energy from a Big Six provider

Energy provider: Npower
Green electricity: 100%
Green gas: n/a
Renewable sources: hydroelectricity and wind
Carbon offsetting: Yes
Exit fee: £30 per fuel
Reasons to buy
+100% green electricity+Plant a tree when you switch+Audited as green
Reasons to avoid
-Exit fees

Npower is the best Big Six supplier for green energy because the company offsets carbon, plants a tree when you switch, and has been audited by EcoAct – which certified that its Go Green Energy Fix meets its green standards. Npower’s prices are firmly in the middle of the range, and if you pay by direct debit you’ll get a discount. Plus, it's the only energy provider to have received triple certification from the Carbon Trust Standard, recognising its commitment to reduce carbon, water and waste from its offices. 

best green energy supplier: Ecotricity

(Image credit: Ecotricity)

5. Ecotricity

Ecotricity is the ethical choice. It's the only vegan green energy supplier

Energy provider: Ecotricity
Green electricity: 100%
Green gas: yes
Renewable sources: wind (98%), solar (0.12%) and hydro (0.7%)
Carbon offsetting: Yes
Exit fee: No
Reasons to buy
+Approved by the Vegan Society+Anti-fracking campaigners
Reasons to avoid
-Expensive-Poor reviews when switching away

Ecotricity is the only energy company in the UK to be recognised by the Vegan Society and get its stamp of approval, making it the only vegan energy choice. Its prices are expensive, but if you care more about ethical suppliers than cost, it might be the best choice for you. Ecotricity funds and supports anti-fracking campaigners in England, and has followed in the footsteps of Extinction Rebellion to declare a climate emergency. It also generates its own green gas, although you won’t get 100% green gas from the company. Just beware the negative reviews around closing accounts and switching away from Ecotricity on Trustpilot.

Best green energy supplier: OVO Energy

(Image credit: OVO Energy)

8. OVO Energy

An exciting green energy supplier that's going places

Energy provider: OVO Energy
Green electricity: 100%
Green gas: 15%
Renewable sources: Anaerobic digestion 49%, solar 32%, wind 18%, hydro 1%
Carbon offsetting: Yes
Exit fee: £30 per fuel
Reasons to buy
+15% green gas+Plant trees when you switch+Supports charities through the OVO Foundation
Reasons to avoid
-Exit fees 

OVO Energy started in 2009 as one of the new breed of digital challenger brands looking to take on the Big Six. Ironically, since acquiring SSE and its 3.5 million customers at the end of 2019, OVO is now technically one of the Big Six, though for now they plan to run the two brands separately. 

OVO prides itself on excellent customer service. While it fails to meet Octopus Energy’s achievements in this regard, 87% of nearly 37,000 Trustpilot reviews rate them ‘excellent’ or ‘great’, nonetheless, with only 9% ‘poor’ or ‘bad’. However, it remains to be seen what going from challenger green energy supplier to Big Six will mean for its vision and values. 

Find the best green energy deal for your home | T3 and GoCompare

Find the best green energy deal for your home | T3 and GoCompare
Use our energy comparison tool to find the best green energy deal for your household in minutes. Simply filter your results to show green suppliers, choose your tariff, and we'll take care of the switch for you. Plus, because we’ve partnered with leading comparison site GoCompare, you'll get access to exclusive energy deals that you won’t find elsewhere.

Other green energy suppliers to consider

Interested in what else is out there? Here are a few more leading green energy companies in the UK that are looking to shake up the energy market.

Get a quote from Pure Planet now

Pure Planet
Pure Plant is a digital-only app-based green energy supplier that charges a membership instead of a standing fee. It doesn't mark-up its prices, making Pure Planet the second cheapest green energy supplier in this guide. It doesn’t use nuclear or coal, and offsets all of the carbon from its gas. Get a quote from Pure Planet now.

Get a quote from Green Network Energy now

Green Network Energy
Green Network Energy offers 100% green electricity and 10% green gas. It doesn't generate the energy from renewable sources itself, but it matches your usage by buying green energy. And it has a whopping 4.5 stars on Trustpilot. Get a quote from Green Network Energy now.

Other energy suppliers with green tariffs 

If you're not convinced about switching to a smaller green energy supplier, here's our pick of the best bigger energy companies that also offer a good green tariff.

Get a quote from E.ON now

E.ON gives all its customers 100% green electricity, and its Fix Online v4 tariff is one of the cheapest around. The company is leading the way with generating green energy, and since 2017 has invested more than €9.5 billion in renewables – but E.ON didn’t take the top spot as best Big Six supplier here because it has a lot of negative reviews on Trustpilot. Get a quote from E.ON now

Get a quote from ScottishPower now

ScottishPower offers green energy for a monthly fee of £3 with its Go Green Bolt On. It sold its gas plants and closed its coal-fired power stations, further boosting its green credentials. And while ScottishPower ranks well in some customer polls, it’s got a poor profile on Trustpilot, so we haven’t recommended it as one of the best green energy suppliers. Get a quote from ScottishPower now

Get a quote from British Gas now

British Gas
British Gas gets 43% of its electricity from renewable sources, but its green tariffs will match 100% of the electricity you use with renewable electricity, and offset the carbon footprint of the gas. It has a number of green tariffs to choose from, depending on how long you want to fix the price for, or your energy use habits, but it's one of the more expensive green energy suppliers. Get a quote from British Gas now

What is green energy?

Green energy is simply electricity and gas that’s generated from renewable sources instead of fossil fuels like coal and gas. 'Green gas' refers to Biomethane, which is a naturally occurring gas produced from the breakdown of organic materials and landfill gas. Green electricity, meanwhile, is the electricity produced from renewable sources in the following ways: 

  • Wind power, where wind provides the mechanical energy to turn turbines
  • Solar power, where sunlight is absorbed by photovoltaic panels
  • Hydroelectric power, where fast-flowing water drives the turning of turbines 
  • Wave power, where the motion of waves drives tools like hydraulic pumps
  • Tidal power, where the rise and fall of the tide pushes turbines

Is green energy more expensive?

Green energy isn’t necessarily more expensive. The cheapest suppliers in our price comparison were Outfox the Market and Pure Planet, which are both green energy companies. That said, the most expensive in our price comparison – Ecotricity and Green Energy UK – are also green energy suppliers.

The price difference is usually down to just how green the energy really is. You’ll usually pay more for a supplier that generates its own electricity from renewable sources and provides some level of green gas, and pay less if the supplier simply matches your usage by buying green energy. 

Regardless of the supplier you choose, there are a few tips on how to keep your energy costs low:

  • Consider a fixed-price tariff. Your costs will be frozen so you’ll avoid any price hikes
  • Request a smart meter to keep an eye on your energy usage
  • Wash your clothes on a lower temperature
  • Turn off appliances when they’re not being used
  • Put your heating on a timer
  • Draught-proof your property
  • Shop around for energy quotes - but don't be swayed by price alone. Check fuel mix, customer service and reviews to get a fair picture.
  • Try a tool like Energy Monitor that will alert you when you could switch tariffs to save money.

How to choose the best green energy supplier

When you’re choosing a new green energy supplier you need to check their fuel mix and see if they can guarantee you’re getting green electricity – or if they’ll just offset your usage. You’ll need to decide which option is right for you.

You can find out what type of energy your supplier uses by looking at their fuel mix. Each year, energy companies must report to Ofgem exactly how their energy is generated, which gives us a fair way to see which suppliers are truly green and which still rely on coal, for example. 

You also need to think about the stability of the supplier. You may fear that a smaller company is less reliable – and the news that many have gone bust in the last 18 months won’t allay those fears – but it’s worth knowing that even if your provider goes bust, your supply won’t be interrupted, you’ll just be moved to a different supplier. 

It may well be worth the switch: the smaller suppliers tend to have better service and much happier customers, according to customer satisfaction polls. And some, like Bulb and Octopus have become as well-known as the Big Six suppliers.

* OVO Energy completed its acquisition of SSE in January, 2020, but announced that it intends to keep the two brands distinct, at least for the foreseeable future.

Laura Nineham
Laura Nineham

Laura is a freelance journalist who works with number of consumer brands, including T3, TechRadar, Real Homes and Robb Report. She has a background in writing about green energy, superyachts, travel, and personal finance.