The sun is a permanent source of energy. It reaches the earth in the form of solar radiation, only three quarters of which penetrates the atmosphere. In order to harness this energy source, it must first be captured.
Depending on how this energy is going to be used, there are different catchment systems, and proper harnessing depends on the amount of solar radiation received, which varies depends on the season of the year and time of day.
Solar power can be used for different purposes, such as for generating electricity, for heating and for passive energy harnessing.
The various systems of solar energy help reduce the use of conventional energy for obtaining heat and electricity.
Energy is of course used to manufacture the solar panels, but the amount involved is less than the amount the panels produce, without causing pollution.
Solar power is therefore:
Solar thermal power is used mainly to obtain hot water, to heat swimming pools and for use in home heating. Mixed systems are solar facilities which allow hot water to be obtained whenever there is available sunlight. They are combined with conventional systems, such as natural gas boilers, so that the service can be run as normal when the solar system on its own cannot handle the demand.
Solar collectors are sealed boxes which capture the solar radiation through a glass surface. The solar radiation passes through to internal pipes where it heats the water inside. A supplementary accumulation system allows this type of energy to be used whenever there is a demand for it.
Solar electrical energy is harnessed through the photovoltaic effect: when the sunlight hits the solar cells, it produces an electric current.
Solar cells are normally made of silicon. Silicon is a semiconductor which is capable of generating an electric current through the effect of sunlight.
It therefore produces electricity as a result of the inherent physical properties of the material used (silicon) which reacts to sunlight. These cells are grouped together to form a solar module. Various modules joined together form a solar panel.
The energy output depends on the sunlight, and this energy can be consumed when it is produced at the moment of production or be stored for use later:
In isolated photovoltaic installations where access to the power grid is difficult, batteries - normally of lead-acid - are used to store the power and ensure the power supply.
The most commonly-used photovoltaic systems are those that are connected directly to the power grid. If these systems are used, batteries are not required.
Solar power can also be harnessed using passive systems such as bioclimatic architecture, in other words, by using the architectural design of the buildings to harness the sun's light and heat better.
In this case, the sun's energy is used directly, without any kind of intermediary mechanism, simply by using, for example, the orientation of the building, suitable insulating materials, light apertures in areas of maximum sunlight, eaves, etc.Passive solar architecture can thus help to achieve very significant savings in conventional energy, with less expenditure on electricity and heating.
Winter: In winter the sun is low and the eaves let the light and heat past.
Summer: In summer the sun is high in the sky and the eaves do not let light or heat past.
This is the attention service of the Basque Energy Agency.
