100Green

100Green (formerly known as GEUK) was established in 2001, making it one of the oldest energy firms outside the traditional big firms. 

It was the first energy supplier to launch a tariff using a smart meter to charge customers different electricity rates depending on the time of day. 

In October 2024, 100Green was included in our customer survey and behind-the-scenes assessment of energy suppliers' practices and procedures. It performed well enough in both assessments to become a Which? Recommended Provider (WRP) for the first time.

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100Green score 

We combine the results of our customer survey with an in-depth assessment of companies’ behind-the-scenes practices and policies to give you an overall view. 

Take a look at our table below to see our score breakdown for 100Green:

Here's how 100Green customer and policy assessments break down:

To find out how 100Green compares with other energy companies, see our full results of the best and worst energy companies.

100Green customer review

100Green ranks second out of 16 energy companies when rated by 11,984 members of the public in the annual Which? customer survey.

It received one of the highest customer scores (76%). It received high star ratings compared to many other suppliers in our survey. It received a five-star rating for overall customer service and a four-star rating in all the remaining categories, including ease of contact, accurate energy payments, the usefulness of communications around price caps, clear statements, customer communications and value for money. providing customers with accurate energy payments.

100Green received plenty of feedback from satisfied customers in our survey. One said: 'The quality and standard of the customer service and the uniqueness of their business is exceptional.'

Another happy customer told us: '100Green offers exceptional services that exceed my expectations.'

Which? verdict on 100Green

• Pros Excellent customer service, according to our survey, meets switching targets.
• Cons Has not signed the Energy UK Vunerablity Commitment, not a great option for those on pre-payment meters.

Our 100Green supplier assessment

In September-November 2024, we looked at five aspects of suppliers' business practices and procedures:

• Contacting your supplier – including how and when you can get in touch, and the quality of self-service help online
• How well they deal with complaints – how many complaints suppliers get and how quickly they resolve them
• Supporting customers who need it – including web accessibility, those in vulnerable situations, in financial difficulty, who use prepayment meters, and those who need materials in languages besides English 
• Switching – how easy it is for customers to switch
• Smart meter targets performance in 2023 –the most recent figures available.

100Green received an above-average score (65%) in our assessment of 16 suppliers' practices this year.

It received high marks for its handling of complaints and switching, and for the various methods of contact it provides to customers. It did not perform well when it came to providing help for those who need it (scoring 4 out of a possible 10). This is primarily due to it not being a member of EnergyUK, due to its small size, and therefore not signing up for the voluntary EnergyUK Vulnerability Commitment. That means it may not be a good choice for you if you are struggling with energy debt.

100Green customer service

Customers' feedback in our survey gave 100Green an excellent five-star rating for overall customer service. Only the other two WRPs – Octopus and Utility Warehouse – scored the same. 

UW also did well in our behind-the-scenes assessment of the customer service setup when compared with other firms. 

100Green common complaints 

Some 16% of the 100Green customers in our survey said they made a formal complaint in the last year. This is above average when compared with other providers in our survey. 

Of the few 100Green customers who did make a complaint, the most common reason (for just less than a third) was for missed appointments. 

Does 100Green support prepayment meters?

Yes, 100Green does support traditional prepayment meters. 

With a traditional prepayment meter, customers top up a key or card and insert it into the meter to pay for their current usage and any outstanding debt on their energy account. Cards and keys can be topped up at Paypoint, PayZone, or Post Office outlets.

Find out whether a prepayment meter is right for you.

How sustainable is 100Green?

Sustainability credentials are important when choosing an energy supplier for two thirds of those responsible for choosing their provider. That’s according to our online survey of 3,000 UK adults in August 2024. 

So we factor in a range of sustainability criteria in our annual Eco Provider assessment. 

Here’s how 100Green fared:

• Proportion of renewable electricity sold to customers: 100%. 
• Doesn't generate renewable electricity but buys it from renewable generators which don't get government subsidies. This is important to support these generators.
• The only firm to sell 100% green gas. 
• Offers a time-of-use tariff with low overnight rates and high rates between 4-8pm on weekdays to encourage customers to use power at less popular times.

100Green narrowly missed out on being an Eco Provider this year. It's still among the best for buying and selling renewable power however.

Find out more about the differences between energy companies renewable electricity, and find out how we assessed energy suppliers for sustainability.

Based on information supplied by companies in August 2024 and their most recent published fuel mixes, where available.

Making your home more energy-efficient will save money on your bills in the long term and lower your carbon footprint. Get started with our guides to home energy efficiency.