What Is the Cheapest Form of Energy for UK Homes? Comparing Gas, Electricity, Heat Pumps, Biomass and Solar

“Cheapest” energy in the UK isn’t one-size-fits-all. It depends on your home, tariff, insulation, and how much energy you use and when. Below, we compare gas, electricity, heat pumps, biomass and solar so you can understand real running costs, upfront spend, grants and practical next steps. We’ll also show how switching suppliers and choosing the right tariff can cut bills fast.

How to decide what “cheap” means for you

• Running cost per kWh of heat or power — includes your unit rate, appliance efficiency and, for electricity, heat pump performance (COP/SCOP).
• Standing charges — daily fees can be significant and vary by region and meter type. Always include them in comparisons.
• Upfront cost — boilers, heat pumps, stoves and solar have very different capital costs.
• Grants and VAT — the Boiler Upgrade Scheme (BUS) can reduce heat pump or, in limited rural cases, biomass costs; some energy-saving measures attract 0% VAT.
• Home suitability — insulation, radiator size, available space for fuel or panels, planning constraints.
• Usage pattern — daytime vs evening use, ability to shift loads to off-peak tariffs.

Not sure how to read your bill? Start here: How to Read Gas and Electricity Prices in the UK — Understand Unit Rates, Standing Charges & Calculate Your Bill.

Quick cost comparison at a glance (typical UK ranges)

• Mains gas (condensing boiler): Often around 6–10p per kWh of heat delivered (depends on unit rate and 85–92% boiler efficiency), plus a daily gas standing charge.
• Direct electric heating: Typically the same as your electricity unit rate per kWh heat (e.g., ~20–30p), unless you use off-peak/storage tariffs.
• Heat pumps (air/ground source): Effective heat cost = electricity unit rate ÷ COP. With electricity at 24p/kWh and a seasonal COP of 3, heat ≈ 8p/kWh; with COP 4, ≈ 6p/kWh.
• Biomass (wood pellets): Roughly 7–12p/kWh heat depending on pellet price, boiler efficiency and delivery costs; best suited to off-gas rural homes.
• Solar PV: Lowest-cost electricity when self-consumed; think of a long-term “levelised” cost potentially in the single digits p/kWh after payback. Works best alongside smart tariffs, batteries or a hot water diverter.

Note: Prices and standing charges change regularly; always check today’s tariffs and your regional rates.

Gas vs electricity: which is cheaper day to day?

Mains gas: pros, cons and when it’s cheapest

• Pros: Low unit rate per kWh, familiar systems, quick hot water and heating, wide installer base.
• Cons: Carbon emissions, reliance on a fossil fuel, gas standing charge applies even in low-use months, boiler servicing required.
• Cheapest when: You’re on a competitive tariff, your boiler is efficient, your home is reasonably insulated, and you have consistent winter demand.

Electricity: standard, off-peak and smart time-of-use

• Standard rate: Simple but can make direct electric heating expensive in winter.
• Economy 7/Time-of-use: Cheaper night rates can make storage heaters, hot-water cylinders and EV charging far cheaper. Aligning appliances to off-peak periods is key.
• With heat pumps: Smart tariffs + good COP can beat gas on running costs, especially in well-insulated homes.

Before changing tariffs or suppliers, learn to break down your bill accurately: How to Read Gas and Electricity Prices in the UK — Understand Unit Rates, Standing Charges & Calculate Your Bill.

Heat pumps: when do they beat gas on cost?

How heat pumps save

Heat pumps move heat rather than generate it. Their efficiency is expressed as COP (Coefficient of Performance). Seasonal COPs of 2.5–4 are common in suitable UK homes.

• Effective heat price (p/kWh heat) = electricity unit rate (p/kWh) ÷ COP.
• Example: 26p electricity ÷ COP 3.2 ≈ 8.1p/kWh heat — often comparable to or lower than gas.

When are heat pumps the cheapest choice?

• Well-insulated homes with low-temperature radiators or underfloor heating.
• Households able to use smart/off-peak tariffs for space and water heating.
• Where the Boiler Upgrade Scheme (BUS) grant (up to £7,500 for heat pumps, subject to eligibility) reduces upfront cost significantly.

Other considerations

• Upfront cost: Higher than a gas boiler, but BUS support and 0% VAT on some measures help.
• Design matters: Properly sized units, good emitters, and weather-compensation maximise COP.
• Noise/space: Outdoor unit location and planning constraints may apply.

Biomass boilers and stoves: niche but effective off-grid

Modern pellet boilers can offer stable running costs where mains gas isn’t available. Fuel prices vary by region, delivery and certification. You’ll need dry storage and regular maintenance (ash removal, chimney sweeping).

• Typical running costs: Around 7–12p/kWh heat, depending on pellet price and boiler efficiency.
• Best for: Rural, off-gas homes with space for bulk delivery and where local supply is reliable.
• Grants: Limited BUS support may be available for certain off-gas rural properties, subject to strict criteria and sustainability rules.

Solar PV (and solar thermal): cutting electricity and hot water costs

Solar PV economics

• Self-consumption is king: every kWh you use directly avoids buying at the retail rate.
• Smart Export Guarantee (SEG): Get paid for exported power; rates vary by supplier.
• Add-ons: Battery storage and hot-water diverters increase self-use; pairing with a heat pump can maximise value.

While PV doesn’t directly heat your home, it can power a heat pump cheaply in spring/autumn, and a diverter can heat hot water on sunny days, reducing gas or grid-electricity use.

Solar thermal

• Efficient for hot water rather than space heating.
• Lower running costs but limited seasonal output; pairs well with combi alternatives or cylinders.

Practical steps to find your cheapest option

1. Fix the fabric first: Insulate loft, walls and floors; draught-proof; upgrade glazing. See The Ultimate Guide To Energy Efficiency – How To Reduce Costs At Home.
2. Understand your current costs: Check unit rates and standing charges and calculate annualised costs from your meter reads. Use our guide: How to Read Gas and Electricity Prices in the UK — Understand Unit Rates, Standing Charges & Calculate Your Bill.
3. Model heat pump vs gas: Estimate a realistic COP (ask installers for heat-loss and emitter checks). Compare electricity ÷ COP with gas per kWh including efficiencies.
4. Consider off-peak tariffs: If you can shift loads (EV, immersion heater, heat pump pre-heat), time-of-use tariffs can slash costs.
5. Check grants and planning: BUS eligibility, local rules, and any requirements for listed buildings or conservation areas.
6. Get multiple quotes: For boilers, heat pumps, biomass or solar. Compare like-for-like, including warranties and servicing.
7. Reduce usage now: Quick wins add up. Try 10 Proven Tips To Slash Your Home Energy Bills And Save Money and Simple Ways To Save Money At Home – Cutting Energy Costs Made Easy. Also see Sure! Here Are 10 Evergreen Blog Headlines Related To Saving Money At Home, Cutting The Cost Of Energy, And Finding Cheap Energy Options –.

Switching suppliers: don’t overpay for the same kWh

Even without changing your heating system, you can often pay less simply by being on the right tariff. Differences in unit rates, standing charges, exit fees and SEG export rates can be significant across regions and meters (credit vs prepayment). Fixed deals may protect against rises; variable tariffs can suit if prices fall. Smart tariffs reward flexibility.

• Compare regularly — prices change frequently.
• Match tariff to usage — daytime-heavy vs night-heavy households benefit from different structures.
• Bundle thinking — if you’re all-electric with a heat pump or EV, optimise electricity first; gas-light homes might focus on low standing charges.

So, what’s the cheapest form of energy?

For many UK homes today, gas remains cheap per kWh of heat on a simple like-for-like basis, but heat pumps can match or beat gas where COPs are solid and smart tariffs are used. Biomass can be competitive off-gas, while solar PV offers some of the lowest lifetime-cost electricity when you self-consume. The true winner depends on your home and tariff. The quickest saving for most households is to improve efficiency and switch to a sharper energy deal.

Ready to cut your bills? Use Cheapest Utility Provider to compare live gas and electricity tariffs, find smart/off-peak options, and see if switching supplier could save you money today. Then plan your next step — whether that’s a better boiler, a heat pump, biomass or solar — from a position of knowledge.

Compare energy deals now on Cheapest Utility Provider and start saving.