Octopus Energy 100Green (September 2026)
Overview
There is no single best choice: compare price, service, app and green-energy evidence separately.
About Octopus Energy and 100Green
Who is Octopus Energy?
Octopus Energy started in 2015 and has grown to become the UK's largest energy supplier. It supplies millions of homes and runs in several other countries. The company builds its own technology to manage customer accounts and billing.
Products & services
Awards & recognition
Who is 100Green?
100Green started in 2001 under the name Green Energy UK. It is a smaller, specialist supplier that focuses entirely on green energy. It puts a lot of effort into customer service and green energy rather than trying to be the cheapest supplier on the market.
Products & services
Awards & recognition
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Tariffs and pricing
Octopus Energy currently provides the cheaper deals in this comparison. Its lowest-priced option overall is the Flexible Octopus variable tariff at £1,598 a year, which has no fixed term and no exit fees. By comparison, 100Green's cheapest deal is the Exclusive Spring 100% Green 12M September 27 fixed tariff, costing £1,717 a year with no exit fees. This leaves Octopus Energy £119 a year cheaper overall.
Households preferring to lock in their rates will find Octopus Energy's cheapest fixed deal costs £1,642 a year on a 12-month term, though it carries a £100 exit fee. 100Green's lowest-priced fixed deal is the aforementioned Exclusive Spring 100% Green 12M September 27 tariff, which costs £1,717 a year for 12 months but avoids exit fees entirely.
For those considering variable options, Octopus Energy's standard tariff is £1,598 a year, while 100Green's Sparkling SVT equivalent costs £1,762 a year. Neither of these variable options charges exit fees.
| Metric | Octopus Energy | 100Green |
|---|---|---|
| Cheapest variable tariff | £1,598 / year | £1,761 / year |
| Cheapest fixed tariff | £1,641 / year | £1,717 / year |
| Cheapest tariff exit fee | £0 | £0 |
| Cheapest fixed tariff exit fee | £100 | £0 |
Tariff Options
Octopus Energy
The supplier offers standard variable and fixed-term tariffs, alongside smart and specialist tariffs for electric vehicles, heat pumps, and solar panels.
100Green
The supplier offers standard variable and fixed-term tariffs, as well as time-of-use smart tariffs for customers with smart meters.
Customer reviews
Both suppliers receive positive feedback on Trustpilot, though Octopus Energy performs better on the data compared here. It holds a 4.8 out of 5 rating from over 857,000 reviews, with 90% of customers awarding five stars. Reviewers frequently highlight friendly staff and prompt responses. 100Green also scores well, achieving 4.6 out of 5 from 1,559 reviews, with 74% at five stars. Customers note 100Green's welcoming staff and smooth switching process, although some mention occasional communication delays and billing issues.
In the Which? annual survey, Octopus Energy achieves a score of 74, while 100Green scores 72. Octopus Energy performs better regarding help for those who need it, scoring 10 out of 10, and switching, where it scores 3 out of 5 compared to 100Green's 1 out of 5.
Conversely, 100Green scores higher on complaints handling, receiving 12 out of 15 compared to Octopus Energy's 8 out of 15. Both suppliers earn 4 out of 5 for overall customer service.
App experience
Octopus Energy achieves higher scores for its mobile apps. The iOS app holds 4.8 out of 5 from 254,000 ratings, and the Google Play version scores 4.4 out of 5 from over 47,000 ratings. The Google Play app has over a million installs, and both apps have been updated recently.
100Green's apps currently show low scores, sitting at 1.1 out of 5 on iOS and 1.2 out of 5 on Google Play. However, these figures are based on small samples of 21 and 32 ratings respectively, making direct comparisons with larger suppliers difficult. Recent iOS reviews for 100Green suggest the app is basic and lacks user-friendly features.
Service and support
Average wait: 1.3 min
Hours: Mon–Thu 9am–5pm, Fri 9am–4pm, closed Saturday, closed Sunday
Average wait: 7 sec
Hours: Weekdays 8am–8pm, open Saturday and Sunday 9am–1pm
Replies: 86% within 2 days
Hours: 24/7
Replies: 91% within 2 days
Hours: 24/7
Average response: ~1 min
Hours: Business hrs
100Green ranks higher on official service metrics, taking 1st place overall with Citizens Advice and achieving a score of 4.33 out of 5. Octopus Energy places 4th with a score of 3.67 out of 5.
When contacting customer support, 100Green is faster, answering phone calls in an average of 7 seconds, compared to 1 minute 17 seconds for Octopus Energy. 100Green also responds to 90.9% of emails within two days, slightly ahead of Octopus Energy's 86.1%. Additionally, 100Green publishes a social media response time of 55 seconds, whereas Octopus Energy does not currently share this metric.
Both suppliers have formal vulnerability commitments registered with Citizens Advice. Regarding opening hours, 100Green is available on weekdays from 8am to 8pm, and on Saturday and Sunday from 9am to 1pm. Octopus Energy operates Monday to Thursday 9am to 5pm, Friday 9am to 4pm, and is closed on weekends.
| Metric | Octopus Energy | 100Green |
|---|---|---|
| Social media response time | N/A | 55 seconds |
Complaints and performance
In the first quarter of 2026, 100Green received 144 complaints for every 100,000 customers. Octopus Energy received 538 complaints per 100,000 customers during the same period.
Green Energy Comparison
Octopus Energy
According to Citizens Advice data, the electricity Octopus Energy supplies is a mostly renewable mix, with some nuclear. The company says the electricity it supplies to domestic customers is 100% zero-carbon, matched using Renewable Energy Guarantee of Origin (REGO) certificates. It also builds and runs its own wind and solar farms to generate green power.
100Green
According to Citizens Advice data, the electricity 100Green supplies is 100% renewable. It offers customers the option of 100% green gas through its 100 Origin tariff. The company makes this gas from biomethane and does not use carbon offsetting to make its gas green.[1]
Our verdict
| If you care most about | Choose |
|---|---|
| The lowest annual cost on our assumptions | Octopus Energy |
| Overall customer service | 100Green |
| A greener fuel mix | 100Green |
There is no single best choice: compare price, service, app and green-energy evidence separately.
Use the decision table to match the available evidence to the factors that matter most to your household.
- Cheapest variable tariff at £1,598 / year
- 4.8 Trustpilot from 857,633 reviews
- Top-4 Citizens Advice ranking
- iOS app rated 4.8 out of 5
- 86% of emails answered within 2 days
- 12% of Google Play ratings are negative
- Cheapest variable tariff at £1,762 / year
- 4.6 Trustpilot from 1,559 reviews
- Top-1 Citizens Advice ranking
- 91% of emails answered within 2 days
- 94% of Google Play ratings are negative
Frequently asked questions
Which is cheaper, Octopus Energy or 100Green?
On the stored annual-cost assumptions, Octopus Energy is £1,598 and 100Green is £1,717. Octopus Energy is lower by about £119 a year.
Can Octopus Energy and 100Green complaint rates be compared directly?
Yes. Both figures cover Q1 2026: Octopus Energy reports 538 complaints per 100,000 customers and 100Green reports 144.
Which supplier leads on customer service?
On the comparable customer-service measure used in the decision table, 100Green leads.
Which supplier has the better app evidence?
The supplied data does not support a like-for-like app winner.
Do tariff eligibility rules matter?
Yes. Specialist, time-of-use, EV, heat-pump and export tariffs can have equipment, meter or account requirements. Check the current supplier terms before applying.
Which supplier has the greener evidence?
On the comparable green-energy measure used in the decision table, 100Green leads. This row is based on published fuel-mix percentages.
Which is better overall, Octopus Energy or 100Green?
There is no single overall winner in this repaired draft. Price, service, app and green-energy evidence are kept as separate choices in the decision table.
When was this comparison updated?
The structured source payload is for September 2026.
What changed this month
This month, Octopus Energy's iOS app days since last update fell from 6 to 1, Octopus Energy's play store days since last update fell from 2 to 1, and Octopus Energy's fixed tariffs available fell from 2 to 1. There were 27 other data changes this month — see the full changelog below for details.
Data changes this month (34)
Octopus Energy
- Trustpilot reviews837,814 → 857,633
- iOS app ratings count249,000 → 254,000
- iOS app days since last update6 → 1
- iOS sampled reviews avg stars2 → 1.67
- Play Store rating4.3956046 → 4.3669577
- Play Store ratings count47,091 → 47,238
- Play Store days since last update2 → 1
- Play Store positive ratings %85.5 → 84.5
- Play Store negative ratings %11 → 11.7
- Play Store neutral ratings %3.5 → 3.7
- Play Store net-positive %74.5 → 72.8
- Cheapest variable tariff£1,792.32 → £1,598.38
- Cheapest fixed tariff£1,841.19 → £1,641.76
- Cheapest tariff£1,792.32 → £1,598.38
- Tariff count3 → 2
- Fixed tariffs available2 → 1
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
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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.