solvärme

Solvärme, or solar heating, refers to technologies that capture sunlight to produce heat for buildings, hot water, or industrial processes. It is a key category within solar energy, distinct from solar photovoltaic electricity.

Active solar heating uses collectors to heat a circulating fluid (water or glycol) that transfers heat to a storage tank or directly to a building’s heating system. Passive solar design relies on building orientation, insulation, thermal mass, and daylighting to collect and store heat with minimal mechanical intervention.

Collectors are typically flat-plate or evacuated-tube types. Heat is stored in domestic hot water tanks, radiant floors, or other thermal storage media. Some systems include seasonal storage to hold heat for winter use.

Applications include domestic hot water, space heating, swimming pool heating, and certain industrial processes. In colder climates these systems are usually paired with auxiliary boilers or heat pumps. The amount of heat provided by solvärme is described as the solar fraction and depends on climate, system size, and storage capacity.

Performance and economics: efficiency is influenced by collector type, orientation, and insulation. In temperate regions solar fraction for hot-water systems often ranges from about 20% to 60%, with higher shares in well-insulated homes and with larger storage. Upfront costs vary; operating costs are low, and many countries offer incentives or subsidies for solar thermal installations.

Environmental impact: solar heating reduces fossil fuel consumption and greenhouse gas emissions when it displaces conventional heating. Lifecycle impacts depend on manufacturing, transport, and end-of-life recycling.

History: solar heating dates to early 20th century experiments and saw broad adoption after mid-century energy crises. In Northern Europe, solvärme remains common in new construction and retrofit projects due to favorable sun exposure and cold climates.