Flex Energy for UK Businesses: How Flexible Energy Contracts Work
Flex energy allows businesses to buy gas and electricity in stages, locking in portions of their expected usage as wholesale prices change. It offers greater purchasing flexibility but exposes unpurchased energy to price rises. This guide explains how flexible contracts work, their risks, and whether they suit your business.
Is flex energy right for my business? A quick check
Note: Flexible energy tends to be worth assessing if most of the following apply. If they mostly don’t, a fixed contract is usually the simpler and safer route.
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| Question | Points towards flexible | Points towards fixed |
|---|---|---|
How much energy do you use? | High consumption; often multi-site or half-hourly metered | Lower or moderate consumption |
| How important is a predictable budget?s | You can absorb some price variation | Certainty matters more than a possible saving |
Who will make buying decisions? (opinion) | A finance or energy lead, or an adviser, who reviews the market regularly | Nobody has the time to monitor prices |
Do you have a purchasing policy? | Agreed limits on risk and sign-off | No formal policy |
How would a price spike affect you? | Manageable within margins or cashflow | Would cause serious financial strain |
What is flex energy?
Flex energy, or a flexible energy contract, is a business energy agreement that lets you buy your gas or electricity in several purchases (tranches or “clips”) over the life of the contract, instead of agreeing one fixed price at the start.
In a standard fixed contract, you agree a single price per unit (usually in pence per kilowatt hour, p/kWh) for a set term, and the supplier carries the risk of the market moving. In a flexible contract, the supplier gives you access to the wholesale market through a framework, and you decide when to fix portions of your expected volume. The price for each portion reflects the wholesale market at that moment, plus the supplier’s margin and costs.
Flexible, variable and deemed: three different things
Flexible contract
A managed purchasing strategy, usually on a defined term, where you choose when to fix volume.
Variable tariff
A rate that can change at the supplier's discretion, typically on notice. See our guide to fixed vs variable business electricity
Deemed or out-of-contract rates
Default rates charged when you have no agreed contract, often higher than contracted rates. See deemed rates
Some suppliers and brokers also use “Flex” as a product or brand name, and the term is used for other things too, such as on-site power generation or demand-side flexibility. On this page, flex energy means a flexible way of buying business energy.
How does flexible business energy work?
Under a flexible contract, your expected usage is forecast, a supplier framework is agreed, and you then fix portions of that volume at times you choose within agreed limits. Volume you haven’t yet fixed is exposed to wholesale price movements until it is.
Assess your usage
Your consumption history, meter type (including half-hourly meters), sites and seasonality are used to forecast volume for each fuel.
Set a strategy and risk limits
Decide how much volume to fix, over what period and with what approval process. This is often written down as a purchasing or risk policy.
Choose a supplier and product
Suppliers offer different flexible products, minimum volumes, credit requirements and ways of handling non-energy costs.
Buy in tranches
Within the contract window, you instruct purchases of set volumes (for example a percentage of annual volume) at the then-current market price.
Monitor and adjust
Market movements, forecast changes and business plans are reviewed regularly. Some products also allow you to "unfix" or resell volume; others do not.
Complete the position
By the deadline set in the contract, any remaining volume must be fixed, or it is priced as the contract states.
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WHAT YOU MAY NEED
Recent bill. MPAN . Annual usage. Contract end date
The Switching Timeline:
Because flexible contracts follow market movements, the energy price you pay across the term is an average of when you bought, not a single announced rate. That is the main reason it can be better or worse than fixing, and why it needs oversight. For wider context, see our overview of energy procurement
What are you actually buying? Commodity and non-commodity costs
Your business energy bill has two parts: the commodity (the gas or electricity itself) and non-commodity costs (network, policy and other charges). In many flexible contracts, you fix the commodity in tranches while some non-commodity costs are passed through at actual cost.
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| Component | What it covers | How it is usually treated in a flex contract |
|---|---|---|
Commodity (wholesale energy) | The cost of the energy itself, plus supplier margin | Fixed in tranches at the market price when you buy |
| Network charges | Costs of transporting energy across the transmission and distribution networks | Often passed through; may change during the contract |
Balancing and system costs | Costs of keeping the grid balanced | Often passed through |
Policy and environmental costs | Government-backed schemes and levies | Often passed through or set by rule |
Climate Change Levy (CCL) and VAT | Taxes on business energy use (some users receive discounts or exemptions) | Added to the bill as applicable |
Standing charges | Fixed daily charges for supply and metering | Depends on the contract |
The split varies by contract, supplier, meter type and site. Ask for a written breakdown of which costs are fixed and which are passed through before you sign. Pass-through means your total cost can move even when your energy price is fixed. Note that, unlike household tariffs, business energy is not subject to the Ofgem price cap, so there is no capped fallback rate.
Flexible vs fixed business energy: what is the difference?
A fixed contract locks one unit rate for the whole term, giving budget certainty. A flexible contract lets you buy in stages, which can capture lower prices but exposes you to higher ones. Fixed shifts price risk to the supplier; flexible shifts more of it to you.
| Fixed contract | Flexible contract | |
|---|---|---|
Price set | Once, at signing | In tranches, at times you choose |
| Budget certainty | High for the energy price | Lower until all volume is fixed |
Price risk | Mostly with the supplier (priced in) | Mostly with you |
Benefit if prices fall | Limited; you stay at the agreed rate | Possible, if you buy after falls |
Exposure if prices rise | Protected for the term | Exposed on unfixed volume |
Effort required | Low | Moderate to high; needs oversight |
Typical users | Most SMEs and many larger businesses | Larger, higher-consumption users with support |
Non-commodity costs | Often fixed, but varies | Often passed through |
A fixed rate includes a premium for the risk the supplier takes. Flexible buying avoids paying that premium on every unit but means you take the market risk yourself. Neither is better in all conditions. For more on contract types, see business energy tariffs explained
Is flexible energy cheaper?
Not automatically. Flexible energy can cost less than fixed if you buy during price dips, but it can cost more if prices rise before you buy. There is no guarantee of savings, and results depend on the market, your purchasing decisions and your consumption.
Anyone who promises a fixed percentage saving from flexible energy cannot know what the market will do. Reasons it might be cheaper: you avoid the risk premium in a fixed price, and you can spread purchases to reduce the chance of buying everything at a peak. Reasons it might not be: poorly timed purchases, high unfixed exposure during a price spike, and pass-through cost changes. Comparing outcomes also needs care, because fixed and flexible contracts are rarely compared fairly after the event.
Benefits of flexible energy
Potential to avoid fixing at a peak
Spreading purchases reduces the impact of one badly timed decision.
Possible lower average cost
you avoid paying a full fixed-price risk premium on all volume.
More control
you decide timing and proportions, within contract limits.
Strategy tailored to your business
purchasing can reflect production, seasonality and budget cycles
Visibility of the market
you see how wholesale movements feed into your costs, which supports better planning.
Fits some multi-site and complex portfolios
one framework can cover several sites.
These are potential benefits, not guarantees, and they depend on how the contract is managed.
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Risks and How to Manage Them
The main risks of flexible energy are exposure to price rises on unfixed volume, less budget certainty, pass-through cost changes, and the time and expertise needed to manage it properly.
Market risk:
prices can rise sharply, especially during periods of volatility.
Budget uncertainty:
your final average price is not known until all volume is fixed.
Pass-through costs:
non-commodity charges can change during the term.
Management burden:
flexible contracts are not "set and forget"; someone must review and decide.
Contract rules(terms & conditions of contact):
minimum volumes, deadlines for fixing, credit requirements and penalties for volume variation differ by supplier. Check these closely.
Behavioural risk:
waiting for a better price can mean missing a good one. A written policy helps remove emotion from decisions.
Who is flexible energy suitable for?
Flexible energy is generally suitable for larger energy users with the time, resources or adviser support to manage purchasing, and who can accept some price uncertainty. It is not suitable for every business. (Specific EC 175000Kwh 300000kwh)
Often a good fit
• Businesses with high annual consumption, often multi-site and half-hourly metered
• Organisations with a finance or energy lead and a clear purchasing policy
• Businesses whose margins can absorb some price variation
• Businesses working with a broker or consultant who can support ongoing decisions
Often not a good fit
• Small and micro businesses that need predictable monthly costs
• Businesses without time to monitor energy markets or approve purchases quickly
• Organisations where a price spike would cause serious financial strain
• Businesses below the minimum volume or spend that suppliers set for flexible products
Minimum thresholds vary:
Published criteria range from around 1 GWh or £1m annual spend at some suppliers to much higher volumes at others, and they change over time. Some smaller businesses can access flexible-style buying through aggregated "basket" arrangements. We can check what is open to you based on your usage.
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Flexible electricity and gas contracts
Flexible purchasing can apply to electricity, gas or both, but the markets, products and eligibility differ by fuel, so many businesses use a separate strategy for each.
Flexible electricity
Often tied to half-hourly metering, and non-commodity costs can be a large and changing part of the bill. See business electricity
Flexible gas
Typically driven by seasonal demand and the gas wholesale market. See business gas
Renewable options
Some flexible products can be combined with renewable electricity or green gas. See renewable and sustainable energy
Wholesale prices for gas and electricity are linked but don’t move identically, so aligning the two into one strategy needs care.
Flexible energy for larger and multi-site businesses
Larger businesses often use flexible purchasing as part of a wider risk management strategy rather than a single decision. Common approaches include:
Product names and features vary by supplier, so we compare actual terms rather than labels. Where relevant, we also consider contract alignment across sites, forecast accuracy and how purchasing is signed off internally.
Layered (tranche) buying
Fixing a set percentage of volume at regular intervals to average out market timing.
Block and index
Fixing a block of volume while the remainder follows an index price, with rules on when it must be fixed.
Full flexible purchasing
Greater freedom over how much to fix, and sometimes the ability to unfix, with the highest management requirement.
Baskets or aggregated contracts
Pooling several businesses' volume to access flexible purchasing at smaller scale.
When flexible energy may not be suitable
A fixed contract is usually the better choice when you need a known cost for budgeting or lender reporting, you cannot monitor the market regularly, your consumption is below typical flexible minimums, or you have no spare capacity to absorb a price spike. Choosing fixed is a sound decision, not a lesser one. Our guide to fixed vs variable business electricity explains how fixed contracts work in more detail.
How to choose between fixed and flexible energy
Define your priority
Certainty, lowest possible average cost, or a balance
Check your consumption and meter type
Against supplier eligibility
Test your tolerance
what price increase could you absorb without harm?
Decide who owns the decisions
And how quickly they can act
Look at the whole contract
Not just the headline rate: fixed vs passed-through costs, deadlines, volume rules, credit terms and exit terms
Compare options side by side
From more than one supplier, and ask any adviser how they are paid
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How Energy Solutions approaches flexible energy
We are a UK business energy consultancy, founded in 2016, and we give transparent, no-pressure advice. For flexible energy, that means:
2016
Founded
30+
UK suppliers compared
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We do not guarantee savings or prices, and we do not use pressure tactics
We start with whether flexible suits you
If a fixed contract is the better choice, we say so.
We compare options from multiple UK suppliers
30+ rather than promoting one.
We explain the contract in plain English
What is fixed, what is passed through, key dates and volume rules.
We are open about how we are paid
Suppliers pay us commission, which is built into the tariff you pay. We will explain this before you commit.
We support you after the decision,
We compare options from a range of UK energy suppliers to help businesses find the most suitable energy contract, rather than promoting a single supplier.
Our process
Share your details
Upload a recent bill or tell us about your sites and usage.
Free review
We assess your consumption, risk tolerance and budget needs.
Options explained
We compare fixed and flexible routes from suppliers who can quote for your profile.
You decide
No obligation, no pressure
Set-up and support
We help with the switch or contract set-up and stay available for questions as your contract runs.
Frequently asked questions
Flex Energy FAQs
Still unsure where to start?
Request a review and let the team identify the most relevant next step. There is no requirement to switch.
What is flex energy?
Flex energy (flexible business energy) is a contract structure where you buy your gas or electricity in stages – often called tranches or clips – instead of fixing your whole unit rate on one day. You agree the supplier and contract up front, then choose when to lock in portions of your expected usage as wholesale prices move. Anything you haven’t locked in is exposed to market movements.
Is flexible energy cheaper than fixed?
Not automatically. A flexible contract can work out cheaper if you buy during price dips and avoid fixing at a peak, but it can cost more if prices rise before you have bought. Fixed contracts include a premium for the supplier carrying that risk; flexible contracts move the risk to you. The outcome depends on market movements, your buying decisions and your consumption.
What is the difference between flexible and variable energy tariffs?
A flexible contract is a managed purchasing strategy: you decide when to fix portions of your volume, usually on a defined contract term. A variable tariff simply moves with the supplier’s pricing, which they can change, often on notice. “Flexible” is also not the same as deemed or out-of-contract rates, which apply by default when no contract is in place and are often expensive.
How does buying energy in tranches work?
Your annual or contract-term usage is forecast, then divided into portions (tranches or clips) that you fix at different times. For example, a business might fix part of its volume now, more in spring and the balance in autumn. Each tranche is priced at the wholesale market at that moment, plus the supplier’s margin and costs. Any volume left unfixed is typically priced at the market rate when it is used or when the supplier’s terms say it must be fixed.
What size of business can use a flexible energy contract?
Flexible purchasing is mainly offered to larger energy users. Published minimum thresholds differ widely between suppliers, from roughly 1 GWh a year or £1m annual spend at the lower end to well over 10 GWh at others. Smaller businesses sometimes access flexible-style buying through aggregated “basket” arrangements. Whether you qualify depends on the supplier and your meter type and usage.
What are the main risks of a flexible energy contract?
The main risks are exposure to price rises on volume you haven’t yet fixed, less budget certainty, and the time or expertise needed to manage purchasing. Non-energy costs, such as network and policy charges, may also be passed through and can change. A clear purchasing policy with limits on how much volume stays unfixed helps manage these risks.
What are pass-through costs in a flexible contract?
Pass-through means certain non-commodity costs – such as network charges, balancing costs and policy levies – are charged to you at the actual cost rather than being fixed in your unit rate. Many flexible contracts are structured this way, so your total bill can change even when your energy price is fixed. Always check which costs are fixed and which are passed through.
Can I use flexible energy for both electricity and gas?
Yes, in many cases. Flexible purchasing is available for electricity, gas, or both, but products, minimum thresholds and available suppliers vary by fuel. Electricity and gas wholesale markets move differently, so many businesses use different strategies for each. Half-hourly electricity metering is common among flexible customers.
When should a business consider a flexible energy contract?
Consider it if you are a larger energy user, can tolerate some price uncertainty, and have the time, expertise or adviser support to manage purchasing regularly. It is more likely to suit businesses with a defined risk policy, finance-team sign-off and a view over several contract periods. If your priority is a predictable budget, a fixed contract is often the simpler choice.
When is a fixed contract better than a flexible one?
A fixed contract is usually better when budget certainty matters most, when you have limited time to monitor the market, or when you use less energy than flexible products normally require. It gives you a known unit rate for the whole term, so you are protected if wholesale prices rise, though you won’t benefit if they fall.
Does Energy Solutions charge for a flexible energy review?
Energy Solutions doesn’t charge you a separate fee for an energy review. As with our other services, we are paid commission by suppliers when you take out a contract, which is built into the tariff price. We will explain this before you commit.
How do I choose between fixed and flexible energy?
Start with four questions: how much budget certainty do you need, how much price risk can you absorb, how much energy do you use, and who will manage purchasing decisions? If certainty and simplicity matter most, fixed is usually better. If you use a lot of energy, can accept variability and have the support to act on market movements, flexible is worth assessing. A broker should explain both without pushing either.