One of the fundamental aspects that must be taken care of the most in any type of air conditioning, heating, or DHW installation, are those that are directly related to safety. Any installation of solar panels must comply with current standards and regulations. It is a legal requirement that also guarantees that the equipment works in optimal conditions and does not suffer breakdowns in its components as a consequence of circumstances and eventual factors.
The main security elements contained in a “typical” installation of low-temperature solar panels thermal for ACS.
Every solar thermal installation needs a liquid to transport the heat. The “ideal” liquid should have a number of characteristics:
- Not toxic
- High heat capacity
- High heat transfer coefficient
- Prevent corrosion
- Do not lose its characteristics over time
Currently, glycol (Ethylene Glycol or Propylene Glycol) mixed with water is the compound that best meets these requirements. The concrete % of the mixture will depend on various factors: type of solar panels, minimum temperature of the place where the installation has been made …
As the temperature of the water increases, it increases in volume. Therefore, an element is needed to absorb the expansions of the water in domestic hot water installations. This is the function of the expansion vessels.
Important: It must be dimensioned in such a way that, even after an interruption in the power supply to the circulation pump, just when the solar panels radiation is maximum, the operation of the installation can be restored automatically when the supply is available again.
They are used to control the pressure in the primary circuit. When the calibration value is reached, the valve discharges liquid to prevent the installation pressure from reaching dangerous limits for the operation of the solar panels collectors and the installed devices.
To avoid dangerous increases in temperature in the primary circuit of the solar panels energy installation, it is necessary to have elements that dissipate this excess heat.
Heat sinks circulate superheated liquid through conduits to dissipate its heat into the air. In principle, they are activated when the liquid has reached a certain temperature prior to that considered dangerous (around 90 ºC).
Its function is to extract the air that may form inside the circuit and allow the mixture of cold water with that from the panel, to avoid the risk of burns at times when the solar panel reaches very high temperatures.
The more marked is the difference between the intensity of solar panels radiation that the panel receives in summer and winter, and the longer the periods in which hot water is hardly required (for example, for vacations or for not being in the home), the more important are the security elements that we have discussed. With them, maintenance costs are reduced, as well as the loss of efficiency and useful life of the installed system.
And as always, we end with our motto: “For hot and cold, renewable is the best.”
How does a hybrid solar panel work? Uniting solar photovoltaic and thermal energy in a single panel
Until recently, photovoltaic and thermal energy were not compatible, most of the time, you had to choose one of them for a single roof. These possibilities have led companies to experiment and that barrier has already been overcome. We are talking about a hybrid solar panel that allows you to obtain hot water and electrical energy in the same installation.
This panel is based on the two technologies mentioned above, so the photovoltaic cells (with their corresponding wiring) are installed in a solar thermal collector. Everything else (hydraulic circuit, casing, and transparent cover) remains as in any conventional collector.
When photovoltaic collectors obtain solar panels radiation, only a small part is transformed into electricity, between 8% and 15% depending on the material. The rest of the radiation is transformed into heat and the hybrid panel uses it to heat water. The built-in hydraulic circuit removes the water from the panel and stores it in a thermally insulated tank.
It is very important to emphasize that hybrid solar panels manage to improve the performance of photovoltaic solar panels. Under normal conditions, a panel can reach such high temperatures that its performance is seriously impaired. But in the hybrid solar panels, the thermal part keeps the solar panels cool, bringing them closer to their ideal temperature. Thus, the performance improves by at least 15%.
By getting the photovoltaic panel to work at its most optimal temperature, it is achieved that it degrades more slowly and works for more years, thus increasing its useful life. It is also noteworthy that a single installation reduces the cost of the two energies.
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