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 2016

This chart provides an estimate of the proportion of different costs in the dual fuel bill of an average domestic customer of the large suppliers in 2015. It is based on information reported by the large suppliers in their annual Consolidated Segmental Statements. For more information, 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 costs43.43%
Network costs23.98%
Environmental and social obligation costs7.35%
Other direct costs0.63%
Operating costs15.80%
Supplier pre-tax margin4.04%
VAT4.76%

More Information

Methodology

To estimate the breakdown of an average gas and electricity bill, we took the sum of each category of costs and pre-tax supply margins as reported by the suppliers for each fuel and then divided by the total number of customers for that fuel. We then added VAT at 5% and summed the implied bill components for gas and electricity together to derive an estimate of the overall costs making up a dual fuel bill.

Note that because it is based on the total costs and customer numbers reported by suppliers irrespective of their tariff type, the bill breakdown for gas will reflect a mixture of the costs of serving gas to dual fuel and single fuel customers – and the same also applies to electricity. As such, the dual fuel breakdown should be considered an approximation in that it will reflect a combination of the costs incurred in serving gas and electricity to both dual fuel and single fuel customers (which may differ if, for example, electricity-only customers consume more electricity than those customers that are also supplied with gas).

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data that can be found in the supplier’s externally published CSS. This is because we have made some adjustments to the way in which exceptional items are reported among suppliers 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 2016

This chart provides an estimate of the proportion of different costs in the gas bill of an average domestic customer of the large suppliers in 2015. It is based on information reported by the large suppliers in their annual Consolidated Segmental Statements.  For more information, 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 costs46.53%
Networks22.88%
Environmental and social obligation costs2.10%
Other direct costs0.62%
Operating costs16.17%
Supplier pre-tax margin6.93%
VAT4.76%

More information

Methodology

To estimate the breakdown of an average gas bill, we took the sum of each category of costs and pre-tax supply margins as reported by the suppliers for each fuel and then divided by the total number of customers for that fuel. We then added VAT at 5% and summed the implied bill components for gas and electricity together to derive an estimate of the overall costs making up a dual fuel bill.

Note that because it is based on the total costs and customer numbers reported by suppliers irrespective of their tariff type, the bill breakdown for gas will reflect a mixture of the costs of serving gas to dual fuel and single fuel customers – and the same also applies to electricity. As such, the dual fuel breakdown should be considered an approximation in that it will reflect a combination of the costs incurred in serving gas and electricity to both dual fuel and single fuel customers (which may differ if, for example, electricity-only customers consume more electricity than those customers that are also supplied with gas).

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data that can be found in the supplier’s externally published CSS. This is because we have made some adjustments to the way in which exceptional items are reported among suppliers 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 2016

This chart provides an estimate of the proportion of different costs in the electricity bill of an average domestic customer of the large suppliers. It is based on information reported by the large suppliers in their annual Consolidated Segmental Statements.  For more information, 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 costs40.09%
Network costs25.16%
Environmental and social obligation costs12.99%
Other direct costs0.65%
Operating costs15.40%
Supplier pre-tax margin0.94%
VAT4.76%

More Information

Methodology

To estimate the breakdown of an average electricity bill, we took the sum of each category of costs and pre-tax supply margins as reported by the suppliers for each fuel and then divided by the total number of customers for that fuel. We then added VAT at 5% and summed the implied bill components for gas and electricity together to derive an estimate of the overall costs making up a dual fuel bill.

Note that because it is based on the total costs and customer numbers reported by suppliers irrespective of their tariff type, the bill breakdown for gas will reflect a mixture of the costs of serving gas to dual fuel and single fuel customers – and the same also applies to electricity. As such, the dual fuel breakdown should be considered an approximation in that it will reflect a combination of the costs incurred in serving gas and electricity to both dual fuel and single fuel customers (which may differ if, for example, electricity-only customers consume more electricity than those customers that are also supplied with gas).

The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data that can be found in the supplier’s externally published CSS. This is because we have made some adjustments to the way in which exceptional items are reported among suppliers 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