The correct design of a solar thermal installation involves anticipating all the circumstances that may damage it and applying strategies to avoid it. One of the factors that can render a solar thermal installation useless is the excess heat captured. Here we explain strategies used to dissipate, reduce or divert excess heat in solar thermal installations.
High Collector Angle of Inclination
This is a measure that does not solve the problem, it only alleviates it and that cannot always be applied depending on other energy needs that are intended to be satisfied with the solar system (such as sanitary hot water). It consists of placing the collectors with a high angle of inclination to capture solar radiation preferably in winter. With this, it is achieved that the more perpendicular rays of the summer fall with greater inclination on the collector and are used less.
Excess Heat Discharged into the Pool
The excess heat produced in the solar thermal system in summer is dumped into a pool / pool. In this way, on the one hand, excess heat in the installation is relieved while achieving a pleasant water temperature for the bathroom. Swimming pools, especially those uncovered when heated, are elements by which large amounts of heat are lost to the atmosphere. This a priori negative factor is helpful when it comes to dissipating excess heat.
Cover the Collectors with Covers
Another option to avoid overheating is to cover the collectors with covers to prevent them from capturing solar radiation. This requires that the collector area be safely and conveniently accessible for donning the covers. An advantage is that you can put the covers only on some of the collectors, while letting the rest work to be able to continue obtaining solar heat without putting the installation at risk and can get help from hot water service Newcastle. In the moments of absence for vacations, perhaps the best option is to cover all the collectors with covers.
Aleros
Through the provision of strategically arranged eaves it is possible to reduce the solar radiation that falls on the solar collectors in summer. This system seeks to take advantage of the greater perpendicularity of the summer sun rays to project the shadow of the eaves on the collectors, allowing only a small part of them to work. During the winter months, due to the greater inclination of the solar rays, the eaves loses its ability to cast shade on the collectors and it can operate at full capacity. This system has the downside that it is very difficult, if not impossible, to apply in buildings already built, since it will be difficult to find ailerons that fit correctly, if they exist. Usually it will be necessary for the architect to take this factor into account when designing and building the house.
Heat Sinks
There are also so-called heat sinks. These devices circulate the superheated liquid through ducts so that its heat dissipates into the air. In principle, they are activated when the heat transfer fluid has reached a certain temperature prior to that considered dangerous (around 90 ºC).
There are dissipators of various models and designs. There are those that direct all the superheated flow from the primary circuit to a unit where the heat is dissipated with the help of fans.
Others instead are structures that are placed in each solar collector and that dissipate only the heat generated by the unit on which they are. This type works by gravity without electronic components and is activated by means of thermostatic valves. It has the advantage that its activation is automatic and does not require surveillance
Seasonal Storage Systems
There are large communal installations carried out in northern European countries that prevent overheating by storing excess summer heat in large tanks to recover part of the heat in winter. However, these systems are complex due to the large accumulation volume required and due to the technical problems that this fact entails.
Overheating in Thermophonic Solar Systems
This type of equipment will tend as a general rule to suffer less variation in radiation levels between summer and winter since they are only profitable, when not possible to use, in intertropical and subtropical climatic zones where the solar radiation is more uniform throughout. year. Furthermore, the very configuration of the system, with a single circuit in which the drinking water passes through the solar collectors, prevents the pressure from rising and causing great damage.
However, when the equipment is not to be used for a while (due to absences, vacations, etc.), to prevent fouling in the primary circuit and unnecessary aging of the equipment caused by high temperatures, it will be advisable to drain the water from the same through the drain cock and / or cover the collector with a cover to prevent solar radiation from entering.