SmartestEnergy and SmartestEnergy Business: which one is your supplier?

SmartestEnergy is a Marubeni-owned energy company with a long history of buying power from generators and selling it to business users. This guide explains the structure from its own pages. Biz Energy is not affiliated with SmartestEnergy and does not rate it.

Who owns it

The group's corporate-backing page says SmartestEnergy is a wholly owned subsidiary of Marubeni Corporation, the Japanese trading house, which acquired a stake in the company in 2000. SmartestEnergy says it entered the UK supply market in 2008 and acquired a UK small-business supply company in 2019. The group also operates in the US, Australia and parts of Europe, which is largely irrelevant to a UK shop but useful for understanding its scale.

Two companies, two audiences

This is the part that confuses people. SmartestEnergy's UK contact page splits customers by size:

If you are	The page sends you to
A large business (over 300,000 kWh a year)	SmartestEnergy Limited, with online forms for customer services, sales, generators and trading
A micro or smaller business (under 300,000 kWh and under £50k annual spend)	The separate SmartestEnergy Business website and company

The small-business arm is SmartestEnergy Business Limited (company number 06468946), an active company registered in Worthing. Companies House shows it traded as Dual Energy Direct Limited until it was renamed on 31 August 2020, and the Energy Ombudsman lists it under both names. If you are a typical microbusiness, expect your contract to be with that company, not the headline group. Check the legal name on your Principal Terms.

Contact routes

For larger customers, the official contact page lists forms and a head-office address in London. For small businesses it points to the Support and Contact section of the SmartestEnergy Business website, a customer login, and a microbusiness quote link. It gave no phone number for the small-business arm, so we have not published one; use the numbers on the SmartestEnergy Business site, as contact details can change.

Reading a contract with a mixed-size supplier

Suppliers that serve both large and small customers often have quite different price structures. Large contracts may be priced on a pass-through basis, where network and policy charges are itemised and move; small ones are usually a single blended unit rate plus a standing charge. Our explanation of non-pass-through and pass-through pricing helps you read the quote.

Worked example: a microbusiness uses 18,000 kWh. Blended offer: 26p/kWh and 65p/day gives 18,000 x 0.26 = £4,680 + (365 x 0.65 = £237.25) = £4,917.25. A pass-through offer shows energy at 15p plus network and other costs of 9p today, plus 65p/day: 18,000 x 0.24 = £4,320 + £237.25 = £4,557.25, but if the pass-through element rose to 12p the cost becomes 18,000 x 0.27 = £4,860 + £237.25 = £5,097.25, which is above the blended price. The cheaper headline is not always cheaper over a year. Read pass-through vs fixed charges.

How size affects your rights

Ofgem's size tests apply whatever a supplier calls you. You are a microbusiness if you have fewer than 10 employees and turnover or balance sheet up to €2 million, or use under 100,000 kWh of electricity or 293,000 kWh of gas a year. That brings limits on rollovers and notice, and a ban on back-billing for energy used more than 12 months earlier. Small businesses (up to 200,000 kWh electricity or 500,000 kWh gas, or under 50 staff with turnover up to £6.5 million) can also use the Energy Ombudsman. See what extra protections microbusinesses get.

Complaints

SmartestEnergy's complaints page says a complex complaint can take up to eight weeks and names the Energy Ombudsman as a next step, with Citizens Advice as support. The Ombudsman usually requires a deadlock letter or eight weeks first, and then you have 12 months. Larger customers above the Ombudsman size limits would rely on their contract's dispute terms. See energy disputes and the Ombudsman.

Switching

As with every business supplier there is no cooling-off period. Check the end date, then follow the switching guide.

Before you sign or renew

• Which company? Check whether the contract is with SmartestEnergy Limited or SmartestEnergy Business Limited, and use that company's contact route.
• Which price basis? Ask whether network and policy charges are fixed for the term or passed through.
• What is the broker cost? If a broker arranged the deal, the cost paid through your bills should appear in the Principal Terms as a total in pounds and pence.
• When does it end? Note the end date and any notice deadline. For microbusinesses, a supplier cannot require notice more than 30 days before a fixed term ends.
• What if you leave early? Get the termination fee, and how it is worked out, in writing.

Meters, settlement and why they matter for larger users

Half-hourly metering

Larger users are charged using half-hourly readings, which record consumption every 30 minutes. A growing number of smaller sites are being moved onto this basis as the market-wide half-hourly settlement programme rolls out, with migrations underway since October 2025 and full implementation expected by May 2027. Read market-wide half-hourly settlement and whether it changes your bill.

Profile classes

If you are not half-hourly, your meter is assigned a profile class, which estimates how your usage is spread across the day for settlement. See which profile class is my business.

Why it affects price

Half-hourly sites can sometimes lower costs by shifting load away from peak times, and their bills may show separate charges. Check for TNUoS and DUoS lines.

Worked example

A workshop uses 90,000 kWh a year, 10% in a peak band. At a flat 25p it costs £22,500. If a time-banded price is 22p off-peak and 38p peak: (81,000 x 0.22) + (9,000 x 0.38) = £17,820 + £3,420 = £21,240, a £1,260 gap, before standing charges. If peak use were 25% the cost would be (67,500 x 0.22) + (22,500 x 0.38) = £14,850 + £8,550 = £23,400, worse than flat. Always test your own profile.

Next steps

• Identify the legal entity on your bill.
• Check whether you are micro, small or larger by kWh.
• Check how your price is built before comparing.
• Browse the supplier overview.