Deall eich biliau nwy a thrydan

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Fideo o fanylion y biliau ynni

Mae eich defnydd o ynni yn ffactor mawr yn y pris a dalwch am nwy ac ynni a gall gwneud newidiadau i'ch defnydd o ynni helpu i leihau eich biliau. Mae ffactorau gwahanol hefyd yn effeithio ar ba mor fawr yw eich biliau nwy a thrydan.

Manylion eich bil ynni

Rydym wedi llunio enghraifft o fil nwy a thrydan, tanwydd deuol nodweddiadol fel y gallwch weld manylion y costau gwahanol o ran eich cyflenwad ynni.

Chart

Javascript is required to render chart Breakdown of a dual fuel bill.

Source: Companies’ consolidated segmental statements.

Information correct as of: August 2017

This chart shows an estimate of the different costs that make up an average dual fuel bill for a typical domestic customer of the six large suppliers. It is based on reported data from the six large suppliers’ annual Consolidated Segmental Statements.

Click the ‘more information’ tab above for information on our methodology.

For information on supplier prices and profits, please see our page Understanding the profits of the large energy suppliers.

Policy Areas:

  • Electricity - retail markets
  • Gas - retail markets

Data Table

Breakdown of a dual fuel bill

Annual costPercentage
Wholesale costs37.88%
Network costs26.03%
Environmental and social obligation costs8.11%
Other direct costs1.17%
Operating costs17.22%
Supplier pre-tax margin4.83%
VAT4.76%

More Information

Methodology

To estimate the breakdown of an average gas and electricity bill, we:

  1. Took the sum of each category of cost (e.g. wholesale, network etc) and the pre-tax supply margin reported by the suppliers for gas. Did the same for electricity.
  2. Divided the gas sum by the total number of customers and added VAT at 5%. Did the same for electricity.
  3. Added together the resulting two figures to get a combined estimate of the overall cost of a dual fuel bill.

Please note that chart calculations are drawn from suppliers’ reported total costs and total customer numbers, irrespective of tariff type. They will therefore reflect a mixture of the costs to supply dual fuel and single fuel customers. As such, the dual fuel breakdown is an approximation – values may differ, for example, if electricity-only customers use more electricity than those customers who are also supplied with gas.

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data in the suppliers externally published CSS. This is because we have made some adjustments to the way exceptional items are reported to improve comparability.

Figures relate to the suppliers’ financial years. Five of the companies (British Gas, EDF, E.ON, npower and ScottishPower) have financial years ending in December, whereas SSE’s financial year runs from April to March. 

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Chart

Javascript is required to render chart Breakdown of a gas bill.

Source: Companies’ consolidated segmental statements.

Information correct as of: August 2017

This chart shows an estimate of the different costs that make up an average gas bill for a typical domestic customer of the six large suppliers. It is based on reported data from the six large suppliers’ annual Consolidated Segmental Statements.

Click the ‘more information’ tab above for information on our methodology.

For information on supplier prices and profits, please see our page Understanding the profits of the large energy suppliers.

Policy Areas:

  • Electricity - retail markets
  • Gas - retail markets

Data Table

Breakdown of a gas bill

Annual costPercentage
Wholesale costs39.42%
Networks24.50%
Environmental and social obligation costs1.60%
Other direct costs1.16%
Operating costs17.95%
Supplier pre-tax margin10.60%
VAT4.76%

More information

Methodology

To estimate the breakdown of an average gas bill, we:

  1. Took the sum of each category of cost (e.g. wholesale, network etc) and the pre-tax supply margin reported by the suppliers for gas.
  2. Divided the gas sum by the total number of customers and added VAT at 5%.

Please note that chart calculations are drawn from suppliers’ reported total costs and total customer numbers, irrespective of tariff type. The chart will therefore reflect a mixture of the costs to supply dual fuel and single fuel customers. As such, the bill breakdown is an approximation – values may differ, for example, if gas-only customers use more gas than those customers who are also supplied with electricity.

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data in the suppliers externally published CSS. This is because we have made some adjustments to the way exceptional items are reported to improve comparability.

Figures relate to the suppliers’ financial years. Five of the companies (British Gas, EDF, E.ON, npower and ScottishPower) have financial years ending in December, whereas SSE’s financial year runs from April to March. 

close

Chart

Javascript is required to render chart Breakdown of an electricity bill.

Source: Companies’ consolidated segmental statements.

Information correct as of: August 2017

This chart shows an estimate of the different costs that make up an average electricity bill for a typical domestic customer of the six large suppliers. It is based on reported data from the six large suppliers’ annual Consolidated Segmental Statements.

Click the ‘more information’ tab above for information on our methodology.

For information on supplier prices and profits, please see our page Understanding the profits of the large energy suppliers.

Policy Areas:

  • Electricity - retail markets

Data Table

Breakdown of an electricity bill

Annual costPercentage
Wholesale costs36.30%
Network costs27.59%
Environmental and social obligation costs14.79%
Other direct costs1.19%
Operating costs16.46%
Supplier pre-tax margin-1.09%
VAT4.76%

More Information

Methodology

To estimate the breakdown of an average electricity bill, we:

  1. Took the sum of each category of cost (e.g. wholesale, network etc) and the pre-tax supply margin reported by the suppliers for electricity.
  2. Divided the electricity sum by the total number of customers and added VAT at 5%.

Please note that chart calculations are drawn from suppliers’ reported total costs and total customer numbers, irrespective of tariff type. The chart will therefore reflect a mixture of the costs to supply dual fuel and single fuel customers. As such, the bill breakdown is an approximation – values may differ, for example, if electricity-only customers use more electricity than those customers who are also supplied with gas.

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data in the suppliers externally published CSS. This is because we have made some adjustments to the way exceptional items are reported to improve comparability.

Figures relate to the suppliers’ financial years. Five of the companies (British Gas, EDF, E.ON, npower and ScottishPower) have financial years ending in December, whereas SSE’s financial year runs from April to March. 

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Pam mae biliau nwy a thrydan yn newid?

Cliciwch ar derm yn ein rhestr termau biliau ynni i gael esboniad o'r ffactorau cost sy'n effeithio ar y pris a dalwch a pham maent yn newid.

Cystadleuaeth

Nid yw Ofgem na'r llywodraeth yn pennu prisiau ynni. Yn hytrach, mae cyflenwyr yn cystadlu â'i gilydd am gwsmeriaid ac mae'r gystadleuaeth hon yn rhoi pwysau arnyn nhw i leihau eu prisiau, neu fod mewn perygl o golli cwsmeriaid.

Costau cyfanwerthol 

Y rhain yw'r rhan fwyaf o'ch bil. Gall newidiadau yn y costau hyn, mewn marchnad gystadleuol, achosi i gyflenwyr godi neu ostwng prisiau.

Costau cyfanwerthol yw faint mae eich cyflenwr yn gorfod ei dalu i gael y nwy a'r trydan i gyflenwi ynni i chi. Gall prynu ynni drwy gyfnewidfa, neu lunio contract â chynhyrchydd trydan neu nwy. Mae rhai cyflenwyr hefyd yn rhan o gwmnïau sy'n cynhyrchu eu trydan eu hunain.

Gan fod mewnforion yn rhan bwysig o gymysgedd ynni Prydain, rydyn ni'n cystadlu â gwledydd eraill amdanyn nhw. Mae hyn yn golygu bod argaeledd byd-eang a'r galw am ynni yn effeithio ar brisiau.

Pan fydd argaeledd yn uchel a'r galw yn isel, mae prisiau yn gyffredinol yn is hefyd. Pe bai'r gwrthwyneb yn wir – y galw yn uwch a'r argaeledd yn is – byddai costau cyfanwerthol yn codi.

Mae pris Nwy Naturiol Hylifedig - LNG - a nwy o rai o wledydd Ewrop yn gysylltiedig â phrisiau olew. Felly, pan fydd prisiau olew yn newid, mae'n effeithio ar brisiau Nwy Naturiol Hylifedig a rhai prisiau nwy Ewropeaidd. 

Gan fod prisiau yn newid yn aml, mae cyflenwyr yn aml yn prynu eu hynni ymlaen llaw, sy'n lleihau'r anwadalrwydd. Mae gan wahanol gyflenwyr wahanol ddulliau gweithredu o reoli'r risgiau hyn.

Er enghraifft, mae'n bosibl bod rhai cyflenwyr yn prynu eu hynni am dariffau safonol gymaint â dwy neu dair blynedd ymlaen llaw.

I gwsmeriaid ar gytundebau tymor penodol, mae cyflenwyr fel arfer yn prynu ynni yn agosach at yr amser y caiff y tariff ei lansio. Mae'r gwahaniaethau hyn yn golygu na fydd newidiadau mewn prisiau cyfanwerthol yn effeithio ar bob cyflenwr a phob tariff yn yr un ffordd ar yr un pryd.

Costau rhwydwaith a chydbwyso

Mae'r rhain yn ymwneud â'r gwifrau â'r pibellau sy'n trosglwyddo ynni drwy'r rhwydwaith a ledled y wlad i'ch cartref.

Codir tâl ar gyflenwyr am gostau cynnal a chadw a defnyddio'r rhwydweithiau hyn, a chaiff y costau hyn wedyn eu trosglwyddo o gyflenwyr i gwsmeriaid drwy filiau. 

Rydym yn pennu rheolaethau prisiau ar gyfer y cwmnïau sy'n berchen ar y gwifrau a'r pibellau hyn gan eu bod yn fonopolïau.  Mae'r rhain yn rhoi terfyn ar y cyfanswm y gallant ei ennill.

Mae'n bosibl y bydd costau rhwydwaith yn amrywio o flwyddyn i flwyddyn, er enghraifft o ganlyniad i newidiadau yn lefelau'r defnydd, a'r modd y dyrennir costau rhwng gwahanol ddefnyddwyr y rhwydwaith.

Hefyd, mae costau cydbwyso cyflenwad a galw. Caiff hyn ei wneud fesul eiliad ar gyfer trydan, ac yn ddyddiol ar gyfer nwy. Mae'r taliadau cydbwyso hyn hefyd yn amrywio dros amser yn dibynnu ar faint mae'n ei gostio i gydbwyso'r system mewn gwirionedd.

Costau rhwymedigaethau i'r Llywodraeth

Mae cyflenwyr hefyd yn cynnwys costau yn ymwneud â rhaglenni'r llywodraeth i arbed ynni, lleihau allyriadau ac annog y defnydd o ynni adnewyddadwy.

Mae'r rhaglenni hyn hefyd yn effeithio ar filiau cwsmeriaid yn fwy anuniongyrchol, drwy eu heffaith ar ddefnydd o ynni mewn cartrefi sydd wedi cael budd o gynlluniau effeithlonrwydd ynni, a phrisiau trydan cyfanwerthol, er enghraifft.

Costau ac elw cyflenwyr

Mae cyflenwyr yn mynd i gostau wrth redeg eu busnes eu hunain (er enghraifft, costau yn ymwneud â gwerthiannau, mesuryddion a bilio). Pan fyddan nhw'n pennu'r prisiau, byddan nhw hefyd yn ceisio cwmpasu'r costau hyn, yn ogystal â gwneud elw.

Costau uniongyrchol eraill

Mae costau uniongyrchol eraill yn cyfeirio at gostau cyfranogiad yn y farchnad, yn cynnwys costau Elexon/Xoserve, costau broceriaid a chomisiynau gwerthiannau cyrff cyswllt ac unrhyw gostau rhaglen mesuryddion deallus 'ehangach' (e.e. costau sy'n gysylltiedig â Chwmni Trosglwyddo Data).

TAW

Telir treth ar werth ar filiau ynni cartrefi.

Sut i leihau eich biliau nwy a thrydan

Gall siopa am gynnig ynni gwell a newid tariff neu gyflenwr ynni wneud gwahaniaeth mawr i'ch biliau - tua £300. Mae'r tudalennau canlynol yn egluro sut y gallwch arbed arian a chael y cynnig gorau i chi:

Mwy o ganllawiau ar filiau ynni