Energy efficiency and thermal solar energy: an indissoluble duo

In this article, we will explain what thermal solar energy is (a non-polluting energy source and, unlike other energy sources, not finite), the relationship between energy efficiency and thermal solar energy, what the advantages of harnessing this energy source are, its uses, and how the capture of thermal solar energy for domestic use works.

Energy efficiency and thermal solar energy

Also called solar thermal energy, thermal solar energy is the exploitation of solar energy to produce heat using thermal collectors or solar panels. Through these collectors or solar panels, water or any other fluid is passed, allowing a portion of the heat absorbed by the collector or solar panel to be transferred to the fluid. Once heated (the solar energy heats the fluids to reach temperatures between 40° and 50°, and should not exceed 80°), it can be used directly or stored for later use.

Uses of thermal solar energy in our homes

• Sanitary hot water (ACS). If the fluid that is heated by the collectors or panels is water, this resulting hot water can be used as domestic water for cooking, heating our homes, or for sanitary and hygienic use.

• Also to produce mechanical energy from which electric energy will be obtained.

• To support the conventional heating system (gas or electric boiler). It is estimated that thermal solar energy can represent between 10% and 20% of the energy demand needed for heating. For this, it is necessary for the installation or boiler to have a plate heat exchanger and a regulator (to prioritize the use of the resulting hot water for ACS).

The Technical Building Code (CTE), which dates back to September 2006, requires the installation of ACS systems with solar energy in new buildings, to comply with the requirements of the Kyoto protocol.

Since it is a clean and renewable energy (it does not emit greenhouse gases), the administration often subsidizes its installation, as its energy efficiency saves conventional energy.

CTE DB HE Energy savings. HE4 Minimum solar contribution of sanitary hot water

The regulation applies to new buildings as well as the rehabilitation of existing buildings, regardless of their use, where there is a demand for ACS and/or for heating covered pools.
The document establishes that the minimum annual solar contribution must be the quotient between the annual value of solar energy demanded by the regulation and the annual energy demand, based on monthly calculations. The CTE establishes a minimum solar contribution percentage depending on the climate zone and the supporting energy source (general for diesel, natural gas, or propane, and Joule effect for the supporting energy source is electric through Joule effect).
When the actual solar contribution exceeds 110% of the energy demand or exceeds 100% for more than 3 consecutive months, it is mandatory to adopt the following measures:

• The installation must be able to dissipate the energy surplus.
• Partially cover the collectors.
• Partially empty the collectors.
• Reuse the excess energy for other applications.