Can you explain the technical terms on your website?

We do our best to make sure our website is clear and jargon free, but sometimes we do have to use technical terms, so here’s a glossary that explains them.

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A B C D E F G H I J K I M N O P Q R S T U V W X Y Z 



What does it mean?


Anaerobic digestion

When organic waste like manure, sewage waste or agricultural waste breaks down, it creates a mixture of methane gas and carbon dioxide, used to make biogas.


Air heat pump

A central heating pump that changes cold air into warm. A unit outside your home absorbs air into a fluid, heats it, and pumps the warm fluid into radiators or heaters.



The practice of renewing an energy plan or other contract automatically without asking the customer’s permission, and probably taking a Direct Debit payment as well.


Better Energy plan

A 12-month fixed plan that gives you great service, with quick, efficient phone and email support from our friendly Bristol-based team. Find out more



Made from vegetable oil, animal fat and recycled grease (including used cooking oil). Can be used in most things that take regular diesel, such as cars or machinery. More about biofuels here.



Made by fermenting sugar and plants. Can be used as a fuel for vehicles – in particular high-performance cars – but usually blended with gasoline to help reduce emissions.



Greener, more environmentally-friendly alternatives to regular fuels such as petrol and oil, made from natural and renewable materials such as wood, grass and food scraps. More about biofuels here.



A by-product of anaerobic digestion. Waste is stirred in methane digesters at high temperatures to create and trap gas, which can be used for heating, cooking and so on.



Biomassis anything that grows – biological matter like wood, grass cuttings, plants, paper or food scraps. Biomass energy is a way of turning it into electricity.


Carbon credits


Businesses and individuals buy these to offset damaging carbon emissions.One credit represents a tonne of CO2 (carbon dioxide) removed or reduced from the atmosphere.


Carbon footprint

The total amount of greenhouse gas emissions created by an organisation, event, product or person.


Clean Energy Cashback Scheme

Now usually known as Feed-In Tariffs (FIT).


Climate change

A large-scale, long-term shift in the earth’s weather patterns or average temperatures, causing changes in rainfall, rising sea levels and melting ice caps. Read more



CO2 is the symbol for carbon dioxide – a colourless, odourless gas that’s essential to life on earth, but also a major greenhouse gas contributing to climate change.


Cold weather payment

A government payment to certain households claiming benefits. Currently £25 for each week of freezing weather between 1 November and 31 March. To find out more, click here


Cool Earth

A charity working with South American communities to protect rainforests at risk of destruction. OVO supports them in protecting 100,000 acres of rainforest. Click here to find out more about how we work with Cool Earth.


Cool-off/cooling-off period

The 14 days after your OVO contract starts (your supply start date). During this period you can cancel your contract at any time, by email or phone, without paying an exit fee.  


Credit balance

When you’ve paid us more than the value of the energy you’ve used. You’ll get our OVO Interest Reward on a credit balance up to the current maximum credit balance for the Interest Reward shown in our Energy Charges list.


Debit balance


When you’ve paid us less than the value of the energy you’ve used. If you’re worried that your payments might be too low, just log into My OVO to change them.


Dual fuel

A plan or tariff where you get both your gas and electricity from the same supplier, on the same contract. It can be more convenient and you might get a discount.

Find out more


Economy 7 and Economy 10


An energy plan that can help you pay less for your electricity, as you pay normal prices in the day but less at night (Economy 7) or during 10 set hours (Economy 10). Economy 7

Economy 10


Emergency credit

If you’re on PAYG and run out of credit on your meter, but can’t top up immediately, this lets you access an extra £5 for each fuel, which you pay back when you next top up. Find out more


Energy company obligation (ECO)

A government initiative encouraging energy suppliers to offer grants to low-income customers, so they can make their homes more energy efficient and cheaper to heat.


Energy debt

Being in debt to your energy supplier/s; struggling to meet gas and electricity bills and falling behind with energy payments, so that you’re in danger of being disconnected.

Energy Debt


Energy monitor

A device that shows how much energy you’re using at any time; some models will also let you measure how energy is being used by individual appliances in your home. Find out more


Energy Performance Certificate (EPC)

A list of statistics showing how energy efficient a property is, rating it for energy use and scoring its carbon dioxide emissions. EPCs


Energy Saving Trust

A UK organisation that promotes energy efficiency, energy conservation and sustainable energy use, in order to reduce carbon dioxide emissions and climate change.


Energy source

The fuel, or source, from which energy is generated. For example, traditional sources like coal, oil or natural gas, or renewables like wind, solar or hydroelectric power.

Energy sources


Erroneous transfer

When an energy supplier takes over a gas or electricity supply from the wrong address. The old and new suppliers will then work together to restore the original supply.


Estimated meter reading

If your gas or electricity supplier has not received an up-to-date meter reading showing what you’ve used, they have to base your bill on an estimated meter reading.


Ethernet port

An Ethernet port and cable can connect your computer to another computer, a local network, or a Smart Gateway. The port looks like a phone socket but slightly wider.

Smart technology


Exit fees

Aka cancellation fees or termination fees. Can be charged by companies if you leave before the end of your fixed term contract. Read more about our position on exit fees here.


Feed-In Tariff (FIT)


This is a government scheme for homes with solar panels: if you generate more electricity than you need, you can sell what’s left back to your energy supplier. Find out how to apply


Fixed plan or fixed tariff

A plan or tariff where your energy unit prices and standing charges stay the same for the length of your contract. Your monthly payments may change, however. To find out more about what tariffs we offer, click here


Geothermal energy


Energy from the natural heat in the earth’s core, in the form of direct geothermal energy, generated by a geothermal power plant, or collected via a ground source heat pump. More details here.


Geothermal power plant

A power plant that accesses heat from the Earth by drilling water or steam wells in a process like drilling for oil.


Greener Energy plan

A 12-month fixed plan, this is our best deal if you want 100% renewable electricity*, plus full service from our Bristol-based team.

Find out more


Greenhouse effect

The natural process by which the atmosphere traps the sun's energy and warms the Earth. Scientists believe humans are increasing the effect artificially.


Greenhouse gases

Gases that occur naturally in the environment, but human activity is increasing their concentrations. Scientists are particularly concerned about the impact of carbon dioxide. Find out more.



An interconnected network that delivers electricity from generating stations along high-voltage transmission lines to demand centres, and then on to individual customers.


Ground source heat pump or geothermal heat pump

A heating system that uses pipes buried in the garden to extract heat from the ground. This heat is then used to heat radiators, underfloor heating and hot water.


In-Home Display (IHD)


A small screened device that comes with your smart meter. It lets you check how much energy you’re using, and what you’re paying, hourly, daily, monthly and yearly.

Find out how to get one here.



The most effective way to make your home more energy efficient and reduce your heating bills. You can insulate your loft, floors and walls, and double-glaze windows. [link to in-depth energy-saving tips article]


Interest Reward (OVO Interest reward)

A 3% reward (rising to 5% in year 3) that we offer Direct Debit customers when they have credit balances. It's our way of giving back the interest we earn when a customer’s account is in credit.

Find out more


Kilowatt hours (kWh)


A unit of measurement that equals the amount of energy you would use if you kept a 1,000 watt appliance running for an hour – or a 100 watt device going for 10 hours. 

Find out more


Meter reading


A meter reading is a group of numbers taken from a gas or electricity meter. These monitor how much energy you’ve used during a period of time.


MPAN number

The number that identifies your electricity supply. You’ll need to know it if you change suppliers – look for it on your energy statements.

Find out more


MPRN number

The number that identifies your gas supply.You’ll need to know it if you change suppliers – look for it on your energy statements. Find out more



Our online account management portal, designed to help you look after your OVO account online. You can use it to check your statement, set up reminders and much more. Find out more


National grid


The organisation that carries energy from power sources to homes and businesses, via a network of overhead lines, underground cables, substations, pipelines and pylons.


Off grid


When your home is not served by the national grid network, so you can’t get mains gas or electricity and need to use other sources such as bottled gas or wind power.



The Office of Gas and Electricity Markets. It was set up to regulate energy companies and protect the interests of present and future electricity and gas customers.


Online management discount

A discount for managing your account online through My OVO. You can save up to £5 (£2.50 per fuel type) a month on any of our plans** – just opt in when you join OVO. Find out more


Paperless billing


Receiving bills and statements by email instead of by post. You might get your bill as an attachment, or receive an email telling you to view and download your bill online.


Pay as you go (PAYG)

When you have a prepayment meter installed in your home, and top up your electricity and/or gas with regular or as-and-when payments instead of paying a monthly bill. Find out more



A service provided at a network of shops and other outlets where you can pay bills, transfer money, top up your mobile, pick up a mail order delivery or pay for parking.


Personal projection

How much we think your energy will cost you for a whole year, based on your OVO plan and how much you’re using. Useful for comparing prices with other energy providers. Find out more


Photovoltaic solar panels

Panels, usually installed on roofs, that capture the sun’s energy by converting sunlight into electricity, which is then fed into the building. Find out more



An online portal, or web portal, is a website that acts as a single entry point or gateway, giving you access to a range of information, services, tools, and links.


Prepayment meter

A gas or electricity meter, fitted in your home, where you pay in advance for your energy by topping up the meter, with a card, or key, or remotely if it’s a smart meter. Find out more


Priority Services Register

A register of vulnerable (e.g. elderly or disabled) people who are entitled to a range of free or priority services from their energy company. OVO customers can register here.Find out more


Renewable Energy Guarantee of Origin certificate


A certificate issued by Ofgem to energy suppliers, showing how much renewable electricity they've bought and sold to their customers. Find out more


Renewable Heat Incentive (RHI)

A government grant towards renewable heating costs in your home. You could claim for biomass boilers, solar water heating, and some kinds of heat pumps. Find out more



Energy from sources that should never run out, such as wind, solar, geothermal, wave, tidal, hydro, biomass, landfill gas, sewage treatment plant gas and biogas. Find out more


Seasonal adjustment


If your current Direct Debit payment won’t be enough to cover the extra energy you use in winter, we may increase your Direct Debit to make sure you stay in credit. Find out more


Simpler Energy plan

Our variable rate plan, with 33% renewable electricity*. Your standing charge and energy unit price can change, but you’re not tied into a fixed contract. Find out more


Smart Gateway

A gadget that plugs into your broadband router and links your smart meter to your My OVO account so you can track your energy use anytime, anywhere. OVO no longer supply these. Find out more


Smart meter

A gas or electricity meter that records how much energy you use and sends the data to your energy supplier, who can monitor it and use it to bill you with total accuracy. Find out more


Smart PAYG+

Our prepayment plan where you can manage your account online and pay for your energy at any PayPoint, online in My OVO, by text or through the OVO Energy app. Find out more


Smart PAYG Standard

Our prepayment plan where you pay for your energy at any PayPoint. We’ll give you an In-Home Display device so you can set alerts and keep tabs on your energy use. Find out more


Smart Thermostat

A thermostat that lets you control your heating and hot water remotely with your smartphone, tablet or computer. Save money as your heating is only on when you need it. Find out more


Solar thermal panels

Panels, usually installed on the roof, that use the sun’s energy to heat water, which is stored in a hot water cylinder and used for baths, showers, laundry and heating. Find out more


Standing charges

Simple, transparent charges that cover the cost of supplying services to your address through the pipes and power lines that carry gas and electricity. Find out more


Switch-over date

A date agreed between your old energy supplier and your new supplier, who will let you know when the new company starts supplying your energy and billing you.




Another name for an energy plan, so with OVO you can choose from: Better, Greener and Simpler, Smart PAYG Standard and Smart PAYG+. 


Tariff information label

Enables you to understand the plan you’re on and compare prices. Find them on suppliers’ websites; your current supplier should print one in your annual statement. Find out more


Termination fee

Aka cancellation fees or exit fees. Can be charged by companies if you leave before the end of your fixed term contract. Find out more



A unit of heat energy that is the energy equivalent of burning 100 cubic feet (often referred to as 1 CCF) of natural gas.


Traditional meter

A traditional gas or electricity meter, from which an energy customer (or engineer) needs to take readings in person. These are gradually being replaced by smart meters. Find out more



A machine for producing continuous power. A wheel or rotor, usually fitted with vanes, is turned by a fast-moving flow of water, steam, gas, air, or other fluid.


Unit rates


The amount your energy supplier will charge you for each unit (one kilowatt for one hour) of electricity or gas you use.


Variable rate plan or tariff


A plan where your unit rates can change as gas or electricity wholesale prices rise and fall, so we can’t guarantee your prices for a year as we do with fixed plans.


Warm Home Discount scheme


A government initiative that can give you a one-off discount on your energy bill, or a voucher if you have a prepayment meter, sometime between October and March.


Watt hours

A unit of measurement equal to the energy you would use if you kept a one-watt appliance running for an hour. Energy suppliers are more likely to use kilowatt hours. Find out more


Wave power

Power generated by harnessing the power of the waves at sea. This is very difficult, so wave power stations are quite rare.


Which? Recommended Provider

A company that has passed all of Which?’s thorough assessments on policy, practices and pricing. OVO is the first and so far only energy company to achieve this.


Wind turbine

A wind turbine works like a windmill. Its blades, or vanes, are turned by the wind, creating energy that’s passed down the shaft of the turbine into an electricity generator.


Winter fuel payment

A tax-free heating allowance, designed to help vulnerable pensioners living in the UK stay warm over the winter. In 2016 it should be between £100 and £300.




*Renewable electricity is generated from wind, solar, geothermal, wave, tidal, hydro, biomass, landfill gas, sewage treatment plant gas and biogas.

**Online Discount – £30.00 per year per fuel added to your account on a daily basis as £0.0822 per day. You can lose your online discount if you do not follow the terms and conditions: Find our full set of Terms and Conditions here.

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