When it comes to renewable energy solutions for buildings, solar energy is often the first technology that comes to mind. However, under the broad label “solar” there are two very different solutions: solar thermal and photovoltaic solar.
Both harness energy from the sun, but they do so in different ways and for different purposes. Understanding these differences is essential to choosing the most suitable solution, especially when planning a new building or a renovation.
What is solar thermal?
Solar thermal systems use solar energy to produce heat. Solar collectors absorb solar radiation and transfer it to a heat transfer fluid, which is mainly used for:
- domestic hot water (DHW) production
- heating integration
- support for industrial processes or centralised systems
The heat produced is stored in a tank (storage cylinder) and used when needed.
Pros
- High efficiency in heat production
- Proven and reliable technology
- Excellent integration with boilers, heat pumps and hybrid systems
- Significant reduction in gas or electricity consumption
Cons
- Limited to heat production only
- Less flexible than photovoltaic systems
- Requires space for storage tanks
- Performance varies depending on seasonality and solar radiation
What is photovoltaic solar?
Photovoltaic solar systems convert sunlight directly into electricity, thanks to the photovoltaic effect of silicon cells. The electricity generated can be:
- used immediately for self-consumption
- stored in energy storage systems
- fed into the grid
Today, photovoltaic technology is one of the main tools for reducing the energy dependence of buildings.
Pros
- Electricity generation for multiple uses
- Possibility of self-consumption and storage
- Integration with heat pumps, electric vehicle charging and home automation systems
- Reduction in electricity bills and emissions
Cons
- Does not produce heat directly
- Efficiency affected by orientation, shading and climate conditions
- Higher initial investment, especially with battery systems
- Variable production throughout the day
Solar thermal or photovoltaic: which one to choose?
The choice between solar thermal and photovoltaic depends on several factors:
- Type of building (residential, commercial, industrial)
- Energy needs (more heat or more electricity?)
- Existing systems (boiler, heat pump, hybrid systems)
- Available space (roof area, technical rooms)
In many cases, the best solution is not an “either/or” choice, but a combined approach.
Integrating the two technologies
Solar thermal and photovoltaic systems can coexist within the same building, working in a complementary way:
- solar thermal covers a significant share of domestic hot water demand
- photovoltaic systems supply electricity to electrical installations and heat pumps
- thermoregulation systems optimise the use of the energy produced
This integration makes it possible to maximise self-consumption, improve overall system efficiency and further reduce emissions.
Solar thermal and photovoltaic solar are two different technologies, but both play a key role in the transition towards more efficient and sustainable buildings.
Solar thermal excels in heat production, while photovoltaic systems offer great flexibility in electricity generation. Properly assessing the advantages and limitations of each solution, together with careful system design and energy management, makes it possible to achieve maximum long-term benefits.
IMIT is committed to supporting the energy transition through informed and responsible choices. Understanding the differences between technologies is the first step towards better investments, which is why we support professionals and end users in achieving maximum comfort with a strong focus on energy efficiency and reduced consumption.