Octopus Energy 100Green (August 2026)
Overview
Octopus Energy is stronger on apps and variable pricing, while 100Green offers the lower overall cost, a cheaper fixed tariff and first-place customer-service rankings.
Octopus Energy leads this comparison due to its highly rated mobile apps and a lower-priced standard variable tariff. Conversely, 100Green may suit households looking for a fixed deal, offering a cheaper 12-month option alongside top-tier independent customer service rankings.
About Octopus Energy and 100Green
Who is Octopus Energy?
Octopus Energy started in 2015 and is now the UK's largest domestic energy supplier. Backed by the Octopus Energy Group and other investors, it runs its customer accounts on its own software system, Kraken. The supplier focuses on smart tariffs that reward customers for shifting their energy use away from peak times, and it also installs green technology like heat pumps, solar panels, and electric vehicle chargers.
Who is 100Green?
100Green started in 2001 and is based in Hertfordshire. It is a smaller, independent supplier that focuses entirely on green energy. It is the only UK supplier to offer 100% green gas alongside 100% renewable electricity. Because buying real green energy costs more, 100Green has an exemption from the Ofgem price cap, meaning its standard prices can be higher than other suppliers, though it does not charge exit fees on any tariffs.
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Tariffs and pricing
100Green's lowest-priced option is the "Exclusive Spring 100% Green 12M August 27" tariff, which costs £1,749 a year. This 12-month fixed contract includes a £0 exit fee. In contrast, Octopus Energy's cheapest offering is the "Flexible Octopus" tariff at £1,792 a year; this is a variable deal with no fixed term and a £0 exit fee.
Households preferring to lock in their rates might consider the "Octopus 12M Fixed July 2026 v5" tariff, priced at £1,841 a year with a £100 exit fee. For those seeking a variable rate from 100Green, the "Sparkling SVT" is available at £1,976 a year.
Tariff Options
Octopus Energy tariffs
Octopus Energy offers a standard variable tariff and fixed-term deals, alongside a wide range of smart and specialist tariffs for electric vehicles, heat pumps, and solar export.
100Green tariffs
100Green offers a standard variable tariff and fixed-term deals, as well as specialist green and time-of-use tariffs.
Customer reviews
Octopus Energy holds a 4.8 out of 5 Trustpilot score, drawn from a substantial 837,814 reviews, with 90% of these users leaving a five-star rating. 100Green maintains a 4.6 out of 5 rating across 1,539 reviews, 74% of which are five stars.
Feedback for Octopus Energy frequently highlights helpful and professional staff, alongside quick issue resolution. While many reviewers note a straightforward user experience, a portion report that email replies can take several days.
100Green customers often mention a personable and understanding approach from representatives. Reviewers also point to fast response times and clear answers to their queries.
In the annual Which? survey, Octopus Energy achieves a score of 74, compared to 72 for 100Green. Octopus Energy receives 10 out of 10 for helping those who need it, whereas 100Green scores 1 out of 5 in the switching category.
App quality and features
Octopus Energy's mobile applications score 4.8 out of 5 on the App Store (from 249,000 ratings) and 4.4 on Google Play (from over 47,000 ratings). A small sample of recent iOS reviews is mixed, with some users praising the app but others reporting smart-meter data bugs.
100Green's apps hold scores of 1.1 on the App Store and 1.2 on Google Play, based on 21 and 30 ratings respectively. Because this sample size is small, direct comparisons with larger suppliers are difficult. Recent iOS reviews for 100Green cite a basic design and occasional login difficulties.
Service and support
100Green ranks 1st in the Citizens Advice table, achieving an overall score of 4.33 out of 5. Octopus Energy places 4th with a score of 3.67.
Call wait times average 7 seconds for 100Green and 1 minute 17 seconds for Octopus Energy. Both suppliers respond to the majority of emails within two days: 100Green at 90.9% and Octopus Energy at 86.1%.
Citizens Advice data shows 100Green records 14.4 complaints per 10,000 customers, compared to 21.3 for Octopus Energy. Both suppliers maintain formal vulnerability commitments. For weekend support, 100Green operates phone lines from 9am to 1pm on Saturday and Sunday, whereas Octopus Energy's lines are closed.
Complaints and performance
In the first quarter of 2026, 100Green received 144 complaints for every 100,000 customers. In the same period, Octopus Energy received 538 complaints per 100,000 customers. This means 100Green had fewer complaints than Octopus Energy.
We only have resolution data for Octopus Energy. It solved 43% of complaints by the end of the next working day and 80% within eight weeks. 100Green has not shared its resolution figures for this period.
The main reason customers complained to Octopus Energy was about customer service. To fix this, the supplier set up an academy to train its staff and hired more people to answer queries. Other common complaints were about billing and meter readings. Octopus Energy is making its bills clearer and improving its computer systems to stop missing bills.
People also complained to Octopus Energy about payment issues and smart meters. The supplier has put £40 million into a fund to help customers who struggle to pay, and it gives out free electric blankets. For meter issues, it is replacing broken smart meters and training staff to fix problems remotely.
100Green has not shared data on why its customers complain or what it is doing to fix problems.
Green Energy Comparison
Octopus Energy
Octopus Energy supplies 100% zero-carbon electricity. Based on Citizens Advice data, its electricity fuel mix is mostly renewable, with some nuclear power. The company invests directly in wind and solar power through its generation arm.
100Green
100Green supplies 100% renewable electricity and 100% green gas. Based on Citizens Advice data, its electricity fuel mix is 100% renewable. Instead of just using certificates to match its power, it buys electricity directly from independent UK renewable generators, such as wind, solar, and hydro sites. Its green gas is biomethane made from farm waste.
Our verdict
| If you care most about | Choose |
|---|---|
| The lowest annual cost on our assumptions | 100Green |
| Overall customer service | 100Green |
| A well-rated mobile app | Octopus Energy |
| A greener fuel mix | 100Green |
Octopus Energy is stronger on apps and variable pricing, while 100Green offers the lower overall cost, a cheaper fixed tariff and first-place customer-service rankings.
Octopus Energy leads this comparison due to its lower-priced variable tariff, substantial volume of positive reviews, and highly rated mobile applications. As the UK's largest domestic energy supplier, it provides a digital experience that scores higher across most app metrics.
100Green may suit households looking to fix their energy prices, offering a 12-month deal that is cheaper than the Octopus Energy equivalent and carries no exit fees. It also secures the top position in the independent Citizens Advice rankings, supported by fast call response times.
Households prioritising a lower-priced variable tariff and highly rated digital tools may find Octopus Energy to be the more suitable choice. Those who prefer to lock in their rates and value top-ranked customer service metrics might consider 100Green.
- Cheaper standard variable tariff
- Highly rated mobile apps
- 90% five-star Trustpilot reviews
- 100% zero-carbon electricity
- More expensive 12-month fixed tariff
- Longer average call wait times than 100Green
- Phone lines are closed at the weekend
- Cheaper 12-month fixed tariff
- No exit fees on any deals
- Ranks 1st with Citizens Advice
- 100% renewable electricity and green gas
- More expensive standard variable tariff
- Very low app ratings from a small sample
- Poor Which? score for the switching process
Frequently asked questions
Which supplier is better overall?
Octopus Energy is stronger on app quality and variable pricing, while 100Green leads on the lowest overall cost, fixed-deal pricing and customer service.
Which supplier has the cheapest tariff?
100Green has the cheapest deal overall with its 12-month fixed tariff. However, Octopus Energy offers a cheaper standard variable tariff.
What do customers say about these suppliers?
Both score highly on Trustpilot. Octopus Energy is praised for its digital tools and helpful staff, while 100Green customers highlight fast responses and a personable approach.
Are their mobile apps easy to use?
Octopus Energy has very high ratings across both iOS and Android. 100Green has very low scores, though these are based on a small number of ratings.
Who is faster to answer the phone?
100Green answers calls in just 7 seconds on average, while Octopus Energy takes 1 minute 17 seconds.
Which one should I choose?
Choose Octopus Energy if you want a cheap variable tariff and a great app. Choose 100Green if you want a well-priced fixed deal and top-ranked customer service.
Do they charge exit fees?
100Green does not charge exit fees on any of its tariffs. Octopus Energy charges a £100 exit fee on its cheapest fixed deal, but its variable tariff is fee-free.
What are their opening hours?
Octopus Energy phone lines are open on weekdays but closed on weekends. 100Green is open on weekdays and also from 9am to 1pm on Saturday and Sunday.
Do they offer green energy?
Yes. Octopus Energy provides 100% zero-carbon electricity. 100Green is a green-energy specialist offering 100% zero-carbon electricity and 100% green gas.
What changed this month
This month, 100Green's play store days since last update rose from 15 to 38, 100Green's iOS app updates in last 90 days rose from 0 to 3, and Octopus Energy's iOS sampled positive reviews rose from 0 to 1. There were 20 other data changes this month — see the full changelog below for details.
Data changes this month (30)
Octopus Energy
- Trustpilot reviews821,111 → 837,814
- iOS app ratings count245,000 → 249,000
- iOS app days since last update9 → 6
- iOS sampled reviews avg starsnow available (2)
- iOS sampled positive reviews0 → 1
- iOS sampled negative reviews0 → 2
- Play Store rating4.4341745 → 4.3956046
- Play Store ratings count46,873 → 47,091
- Play Store days since last update11 → 2
- Play Store positive ratings %86.7 → 85.5
- Play Store negative ratings %10 → 11
- Play Store neutral ratings %3.3 → 3.5
- Play Store net-positive %76.7 → 74.5
- Cheapest fixed tariff£1,697.05 → £1,841.19
- Cheapest tariff£1,697.05 → £1,792.32
- Cheapest tariff exit fee£100 → £0
- Cheapest tariff term12 months → 0 months
- Tariff count2 → 3
- Fixed tariffs available1 → 2
100Green
- Trustpilot reviews1,511 → 1,539
- iOS app ratingnow available (1.1)
- iOS app ratings countnow available (21)
- iOS app days since last updatenow available (38)
- iOS app updates in last 90 days0 → 3
- iOS sampled reviews avg starsnow available (1)
- iOS sampled negative reviews0 → 3
- Play Store days since last update15 → 38
- Avg social media response time55 → no longer available
- Cheapest fixed tariff£1,671.16 → £1,748.8
- Cheapest tariff£1,671.16 → £1,748.8
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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.