Solar Thermal vs Solar PV and Heat Pumps Guide UK

Key Takeaways

• Solar thermal systems collect solar heat to generate domestic hot water, whereas solar PV generates versatile electrical energy.
• Pairing solar PV with an air source or ground source heat pump provides whole-home space heating alongside hot water and appliance power.
• The Boiler Upgrade Scheme (BUS) provides £7,500 capital grants to replace fossil fuel heating systems with heat pumps.
• BUS funding supports air source and ground source heat pumps up to 45kWth individual capacity across England and Wales.
• Hybrid gas-heat pump systems are excluded, with grants limited to one per property.
• System compliance is measured against Building Regulations Approved Document L energy performance standards.

Technology Comparison: Solar Thermal vs PV and Heat Pump

Choosing between solar thermal and solar PV paired with heat pumps involves evaluating system versatility and operational scope:

• Solar Thermal Collectors: Utilize flat-plate or evacuated-tube fluid collectors to heat domestic water cylinders directly. While solar thermal achieves high per-square-meter thermal efficiency in summer, it contributes zero power for space heating during cold winter months.
• Solar PV with Heat Pump: Generates electricity to power heat pump compressors. Because modern heat pumps deliver 3 to 4 units of thermal heat per unit of electricity (COP 3.0 to 4.0), 1kWh of solar electricity yields 3kWh to 4kWh of thermal heat for central heating and hot water.

Boiler Upgrade Scheme: Capital Incentives

Property owners replacing inefficient fossil fuel systems can access significant grant funding:

• Scheme Core Mandate: Through the Boiler Upgrade Scheme, you could get a grant to cover part of the cost of replacing fossil fuel heating systems with a heat pump or biomass boiler.
• Premises Eligibility: You can use the grant to replace a heating system in your home or a building used for your business.
• Territorial Reach: This scheme is open to people in England and Wales.
• Property Limit: You can get one grant per property.

Technology Grant Values and Constraints

Capital grants are categorized across supported heating equipment:

• Air Source Heat Pumps: Provides £7,500 towards an air source heat pump (sometimes called an air-to-water heat pump).
• Ground Source Heat Pumps: Allocates £7,500 towards a ground source heat pump (including water source heat pumps and those on shared ground loops).
• Biomass Boilers: Offers £5,000 towards a biomass boiler.
• Air-to-Air Systems: Delivers £2,500 towards an air-to-air heat pump.
• Individual Capacity Limit: The maximum capacity is 45kWth for individual systems.
• Hybrid Exclusion: You cannot get a grant for a hybrid heat pump system (for example a combination of gas boiler and air source heat pump).

Regulatory Compliance: Building Regulations Part L

Energy conservation across both technology pathways is regulated under statutory standards:

• Statutory Definition: Building regulation in England setting standards for the energy performance of new and existing buildings.
• Residential Standards: Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments.