The Environment

Which is the best Green Electricity Company?

Many energy companies promise to provided 100% renewable energy, some also state this as being provided at zero carbon per KWh. So it is quite hard to work out which provider provides the best green tariff.

Many are not keen on Green Tariffs - The justification given is that although a company might produce 100% green energy when considering the KWs generated and KWs sold to customers, the carbon saving this provides is then undone by various back room dealings . . . .

How to Choose a Green Supplier

We have compiled the below list based on scoring in five categories:

Supplier Strengths Ethics Transparency Complexity REGOs Investment Score Position
Co-Operative Energy Limited Supports Community Schemes 4 4 4 0 0 12 3rd
Ecotricity Group Limited Vegan, No Bio-Mass, Fair Reporting 5 4 5 2 5 21 1st
Green Energy (UK) PLC   3 3 5 1 0 11 3rd
Good Energy Limited Excellent Detailed Reporting 4 5 5 3 0 17 2nd

 There are perhaps 100 companies that have been screened out prior to making the below list. I have not included business suppliers. In short if you want green energy choose a green energy company not a green energy tariff. A green tariff from say a large supplier is likely made "green" by purchasing other renewable generators certificates (REGO or ROC), and not by actually generating any renewable energy. Some large companies even buy in these certificates from abroad, and this adds to complexity and reduces transparency.

Below are explanatory notes:

Generators & Suppliers

A energy company is a supplier, of energy to business or the public. It can also be a generator, but perhaps not. Since 2014 it has become very easy to set up an energy company. So there are numerous small suppliers. These suppliers could provide 100% "green" energy without even owning a single wind turbine or solar panel.


ROCs are key in understanding how green you supplier is.

Why do we have ROCs

In order to push energy suppliers in to being green, the government gives them a target to produce a certain percentage of their power from renewables, this is set at around 30% (2019). For every MWh (1000 KWh) of power generated the generator gets 1 ROC (Renewable Obligation Certificate). In order to sell to the consumer a supplier must obtain 1 ROC, via generating or purchase for ever 3 MWh supplied. (approx.)

What is a ROC

ROCs are essentially the green certificates issued to electricity generators and bought by suppliers to show that they have fulfilled the Renewables Obligation (RO). The following description is taken from

What is ROC Redistribution

So a generator get a ROC for a MWh of energy generated. The number here differ between companies. I have chosen 3 to compare. Figures taken from Ofgem.

Supplier Group Companies Total Obligation (ROCs) ROCs Presented Total Payments Total Redistributed  % Obligation vs Presented Balance: ROC Value vs Redistributed
Ecotricity 1 305,309 305,309 £0.00 £1.8 Million 100% 13%
EDF Energy PLC 3 17, 823,577 14,745,714 £140 Million £86 Million 82% 11%
British Gas Trading Limited 1 12,922,958 10,913,268 £91 Million £63 Million 83% 61%
Octopus Energy Limited 1 198,212 9,927 £9 Million £58,000 5% -90%

Trading of ROCs

Any generator can sell there ROCs to any supplier. Ofgem do not set a price, so behind the scene suppliers are buying ROCs from generators. For a company with lots of renewable generation infrastructure the payments should be low or zero. Because they could present ROCs to cover the 30%, 40% or whatever Ofgem are asking for that year.

For a small new company such as Octopus energy above, it may be hard for them to engage in the ROCs market dominated by big players. And so although they have paid out a great deal of money to Ofgem for not meeting there obligation this may be down to their inability top trade ROCs rather then there failure to generate them.


I am biased towards Ecotricty, I have no financial interest in Ecotricty but I have been a customer for a number of years. They publish a report which tells you what they are doing to reduce carbon, and show you all of there live projects for building wind turbines and solar farms etc.

The fact is that when it comes to ROCs Ecotricity's transparency evaporates. They should have a large surplus of ROCs but no mention is made of this. They are likely selling them to other suppliers to make up there short fall. So for example if we assume that Ecotricity is 100% renewable, and presented 40% approx. then we can assume that it actual had 488,000 ROCs to trade.  Where did the other 188,000 ROCs go? Perhaps they are propping up British Gas, so it can pretend to sell Green Energy to its customers. In truth there is a lack of transparency here that makes informed decision more difficult.

If we look at Good Energys Annual Reporting they teel us exactly what theya re doing with their ROCs.


REGOs are a newer instrument focused on tracing he source of renewable and verify their authenticity, they cannot be double counted.

The Renewable Energy Guarantees of Origin (REGO) scheme provides transparency to consumers about the proportion of electricity that suppliers source from renewable generation. All EU Member States are required to have such a scheme.

The purpose of the certificate is to prove to the final customer that a given share of energy was produced from renewable sources. As such, the primary use of REGOs in Great Britain and Northern Ireland is for FMD. FMD requires licensed electricity suppliers to disclose to potential and existing customers the mix of fuels (coal, gas, nuclear, renewable and other) used to generate the electricity supplied.

Ofgem publish a truly kick-ass spread sheet (if you are in to that kind of thing) which lists the the quantities of certified (REGOs) produced by generator in the UK.

Guarantees of Origin

GOs are a European Market. EU companies may buy REGOs from anywhere in Europe. "British" Gas for example buy GOs from Italy, Denmark and Finland to name but a few.


Supplier REGOs MWh ROCs Obligation MWh Annual Approx. % of Energy with REGO
Co-Operative Energy Limited ?? 666,588 ?? ??
Ecotricity Group Limited 144,000 305,309 620,000 23%
Green Energy (UK) PLC 25,000 41,950 85,000 29%
Good Energy Limited 134,000 197,994 400,000 33.5%

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