100Green Review (September 2026)
Overview
100Green delivers highly responsive phone support and ranks 1st with Citizens Advice, though its smartphone apps currently receive poor feedback.
Who are 100Green?
100Green, formerly known as Green Energy UK, is an independent energy supplier based in Hertfordshire. Founded in 2001, it is one of the UK's oldest green energy suppliers and operates as a smaller domestic supplier.
What sets 100Green apart is its approach to green gas. It is the only UK energy supplier to offer a tariff with 100% green gas, alongside renewable electricity. Because of the higher costs involved in buying genuine renewable energy, 100Green holds a special exemption from the Ofgem price cap.[1]
Products & services
- Gas and electricity
- domestic energy supply
- Green energy
- renewable electricity and tariffs with up to 100% green gas
Awards & recognition
- ✓Which? Recommended Provider — 2026 / Which?
- ✓EKOenergy-certified tariff — EKOenergy
Use our referral link, and we'll both get £50 credit once your switch is complete.
Existing customer? Find out how you can benefit too. T&Cs apply (only one switching offer per household)
Prices
These are the tariffs we have pricing for — the supplier may offer others.
100Green's lowest-priced tariff is the Exclusive Spring 100% Green 12M September 27, a fixed deal costing £1,717 a year. It requires a 12-month contract but carries a £0 exit fee, allowing customers to switch away without penalty.
The supplier also provides a standard variable tariff, Sparkling SVT, priced at £1,762 a year.
Tariff details
This supplier's full tariff range
100Green offers standard variable and fixed-rate domestic tariffs. All tariffs include the supplier's renewable electricity and green gas.
Customer reviews
100Green holds a Trustpilot rating of 4.6 out of 5 from 1,559 reviews. With 74% five-star and 8% one-star ratings, the supplier achieves a net-positive score of 74%.
Reviewers frequently highlight the speed of call answering and the helpfulness of the phone staff. Customers note that speaking directly with advisors provides clear guidance, and several mention that dedicated representatives assist with the switching process.
Conversely, some users report unexpected billing issues and communication delays. 100Green actively monitors its profile, having responded to 100% of its negative feedback, typically within 48 hours.
In the annual Which? energy survey, the supplier achieved a customer satisfaction score of 72. It received 4 out of 5 for customer service, 3 out of 5 for value for money, and 12 out of 15 for complaints handling. However, it scored 1 out of 5 for its switching process.
App experience
100Green's app scores 1.1 out of 5 on the App Store (21 ratings) and 1.2 out of 5 on the Google Play Store (32 ratings). As both platforms feature fewer than 50 ratings, this represents a very small sample size.
A sample of iOS reviews indicates that users find the interface basic and difficult to navigate. Common complaints include connection issues, difficulties adjusting payment settings, and the inability to view bills without downloading them.
Despite these ratings, the apps appear to be actively maintained, with recent updates logged for both the Apple and Android versions. The Google Play Store records over 1,000 installs for the Android application.
Customer service and support
100Green ranks 1st in the Citizens Advice table, achieving an overall score of 4.33 out of 5. The supplier answers phone calls in an average of 7 seconds and responds to 90.9% of emails within two days.
The firm records 14.4 complaints per 10,000 customers. It maintains formal vulnerability commitments registered with Citizens Advice to support households requiring additional assistance.
Support lines are open on weekdays between 8am and 8pm, and on weekends from 9am to 1pm. Accepted payment methods include Direct Debit, cash, cheque, and prepayment.
Complaints and performance
| Metric | 100Green |
|---|---|
| Complaints received per 100k | 144 |
| Resolved same/next day | N/A |
| Resolved within 8 weeks | N/A |
In Q1 2026, 100Green received 144 complaints for every 100,000 customers.
Data showing how many complaints the supplier resolved by the end of the next working day, or within eight weeks, was not available for this period.
Green energy
100Green focuses entirely on renewable energy. According to Citizens Advice data from January to March 2026, the supplier's electricity fuel mix is 100% renewable. The company buys its electricity from a network of independent UK generators, including wind, solar, and hydro sites.
As well as this, 100Green offers a 100% green-gas option using biomethane. This gas is made through anaerobic digestion, a process that breaks down farm waste and other organic matter. By sourcing green gas directly, the company avoids relying on carbon offsetting schemes to make its gas tariffs green, as detailed on its website.
Our verdict
100Green delivers highly responsive phone support and ranks 1st with Citizens Advice, though its smartphone apps currently receive poor feedback.
100Green may appeal to households prioritising traditional customer service. With a 1st place ranking from Citizens Advice and an average call wait time of 7 seconds, it demonstrates highly responsive telephone support.
The supplier is suited to those who prefer managing their account over the phone and want a provider focused on green energy. Conversely, households that rely on smartphone apps for account management may wish to consider alternatives, given the low ratings currently associated with 100Green's digital platforms.
Frequently asked questions
Who is 100Green?
100Green, formerly known as Green Energy UK, is an independent energy supplier based in Hertfordshire. It focuses entirely on renewable electricity and green gas.
How much is 100Green's cheapest tariff?
Its cheapest tariff is the Exclusive Spring 100% Green 12M September 27 fixed deal, which costs £1,717 a year.
Does 100Green charge exit fees?
The Exclusive Spring 100% Green 12M September 27 fixed tariff has a £0 exit fee, meaning you can leave without penalty.
Is 100Green highly rated by customers?
Yes, it has a Trustpilot rating of 4.6 out of 5 from 1,559 reviews, and scores 72 in the annual Which? energy survey.
Does 100Green have a good smartphone app?
The 100Green app has a rating of 1.1 on the App Store and 1.2 on the Google Play Store, though these scores are based on a very small number of ratings.
How long does it take 100Green to answer the phone?
According to Citizens Advice, 100Green answers call centre phone calls in an average of just 7 seconds.
What are 100Green's opening hours?
The supplier is open on weekdays from 8am to 8pm, and on Saturday and Sunday from 9am to 1pm.
Is 100Green a good energy supplier?
It is a strong choice for customer service and fast phone support, ranking 1st with Citizens Advice. However, its smartphone apps have received poor early feedback.
What changed this month
This month, 100Green's iOS app days since last update fell from 38 to 25, 100Green's play store days since last update fell from 38 to 26, and 100Green's Trustpilot 1-star % rose from 7 to 8. There were 13 other data changes this month — see the full changelog below for details.
Data changes this month (18)
100Green
- Trustpilot reviews1,539 → 1,559
- Trustpilot 4-star %12 → 11
- Trustpilot 1-star %7 → 8
- Trustpilot positive reviews %86 → 85
- Trustpilot negative reviews %10 → 11
- Trustpilot net-positive %76 → 74
- iOS app days since last update38 → 25
- Play Store rating1.2413793 → 1.2258065
- Play Store ratings count30 → 32
- Play Store days since last update38 → 26
- Play Store positive ratings %3.4 → 3.2
- Play Store negative ratings %93.1 → 93.5
- Play Store neutral ratings %3.4 → 3.2
- Play Store net-positive %-89.7 → -90.3
- Avg social media response timenow available (55)
- Cheapest variable tariff£1,975.79 → £1,761.9
- Cheapest fixed tariff£1,748.8 → £1,717.28
- Cheapest tariff£1,748.8 → £1,717.28
Written by
Rob Gibbs
Hi, I'm Rob, and I run Energy-Review.co.uk. I initially started this project in 2018 when I was looking to switch energy suppliers and found there wasn't a website that provided simple, data-backed reviews on all the suppliers available. Since then, I have spent a lot of time (too much, some may say!) looking at all publicly available data about each supplier and writing reviews using this information. These reviews are updated as regularly as possible, and any data is backed up by a source where necessary. I have also started writing guides on various energy-related topics, which hopefully you will find useful. If you find any issues, please use our contact form to let us know.
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