So Energy

So Energy is a relatively small energy firm offering fixed tariffs that are 100% renewable. Set up in 2015, it now has around 300,000 customers, after merging with ESB Energy in 2021.

Interestingly, customers have a say in where it sources the electricity from – you can use an online poll on the website to vote for wind, solar, hydro or biomass.

The energy supplier claims to have 'amazing customer service'. To see if that's true, we've quizzed customers and asked them to score the brand on various measures including ease of contacting, usefulness of communications and value for money.

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So Energy 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 So Energy:

Here's how So Energy's customer and policy assessments break down:

Find out how So Energy compares with other energy suppliers: click to see our full results of the best energy suppliers.

Which? verdict on So Energy

• Pros: Customers rate So Energy pretty highly, with particularly good scores for ease of contact and clear statements 
• Cons: Lowest overall score in Which? assessment 

So Energy customer review

So Energy received an above-average customer score, taking joint-fifth place in our ranking of 17 energy companies, as rated by 11,945 members of the public in the annual Which? customer survey. Its fifth place was shared by Which? Recommended Provider Sainsbury's Energy. 

Its customers rated it particularly well for ease of contact and clear statements – it got four stars apiece for these. It received a more middling three out of five stars for other measures, including value for money. To be fair, though, no provider scored more than three stars for this measure, perhaps reflecting generally high energy prices recently. 

Feedback from customers was generally positive, if not glowing. One customer told us: 'I have never encountered any problems or issues and value their clear communication'. 

Another said of So Energy that it has: 'Reliable service, and it's easy to contact and deal with when necessary'.

So Energy customer service

Its customers gave So Energy an average three stars for customer service in our survey. The top performers in this category – Which? Recommended Providers 100 Green, E (Gas & Electricity), Octopus Energy and Sainsbury's Energy – received four stars out of five.

So Energy common issues and complaints

The most common issues experienced by So Energy customers over the last 12 months included smart meters not sending readings automatically (8%), and the supplier setting direct debit payments too high or low (7%). 

Overall, only 2% of customers made a formal complaint over the last year – this is the lowest percentage of any of the suppliers in our survey. 

So Energy supplier assessment

In September-November 2025 we looked at five aspects of suppliers' business practices and procedures. Examples of some criteria within each category are shown below:

• Complaints – how many complaints suppliers get and how quickly they resolve them
  
• Contacting your supplier – including how and when you can get in touch, call waiting times, and the quality of self-service help online
• Help for customers who need it – including those in vulnerable situations, those who use prepayment meters, those who need materials in languages besides English, and web accessibility 
• Smart meters – including performance against 2024 smart meter targets and the proportion of customers' smart meters actually operating in smart mode
• Switching – how well suppliers handle switching.

We did this using a combination of the responses to a survey we sent to suppliers and our own assessments.

While its customers seem to like it, our independent assessment of So Energy's policies and practices brought its overall score down considerably. It ranks right at the bottom of our Which? assessment score table, with just 44%. The next lowest scorers – EDF Energy and Scottish Power – received a score of 50%.  

It didn't score well in any of our five assessments, but did particularly poorly (scoring less than half marks) for complaints, smart meters, and contacting your supplier. While it offers support through a number of channels, including phone, email, social media and WhatsApp, none of these are open (or actively monitored) that much beyond usual working hours, and not at all over the weekend.

Can I join So Energy with a prepayment meter?

No, So Energy doesn't accept customers with prepayment meters at the moment.

Find out whether prepayment energy is right for you.

How sustainable is So Energy?

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 Eco Provider assessment.

Here’s how So Energy fared:

• Proportion of renewable electricity sold to customers: 66.7%
• Doesn't generate renewable electricity. Buys some directly from renewable generators that are subsidised by government.
• So Energy is majority owned by ESB, which operates two gas-fired power stations.
• Trialling a time-of-use tariff for EV drivers.
• Offers installation of solar PV, battery storage, heat pumps and EV chargers.

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.