EXISTING INSTALLATION

The present installation for the production of SHW consists of a fuel oil C heat generator, a heat exchanger and two vertical storage tanks with a capacity of 1500 litres each, which service the en suite bathrooms and the kitchen.

DESCRIPTION OF THE SOLAR ENERGY INSTALLATION

The solar capture field is composed of 18 APOLO brand high-performance flat-plate AP2 model solar panels of 2m² each, thus forming a capture area of 36m². With this solar capture field energy savings are obtained in HSW production in excess of the 75% envisaged initially in the project and an annual efficiency of close on 50%.

The primary circuit between the collector field and the heat exchanger is executed with a copper tube and the heat-carrying fluid is glycolated. This circuit has a system for collection of the heat-carrying fluid in case of safety valve draining or discharge, as well as an automatic filling system for replacing fluid losses, so that the concentration is maintained within the parameters established initially. It also has a buffer tank with the main function in this case of protecting the expansion tank diaphragm, thereby extending its useful life. To prevent inverse flows on account of natural circulation assisted by the fact of the storage tank being at a level lower than the solar collector field and to prevent thereby the energy losses to which it would give rise, a check valve is installed both in the circuit outgoing and return section.

The energy produced by the collection field is transferred to the heat exchanger and from this to the solar storage tank with a capacity of 1500 litres, which means that the water can be stored at a temperature of 60ºC. A second storage tank is provided, series-connected to the solar tank, also with a capacity of 1500 litres, which is supplied by the heat exchanger and fuel oil boiler. The conventional system completes the SHW preparation needed on days when there is not sufficient insolation. This second tank may also be heated with the solar collector field on days when sufficient solar radiation is received. For this purpose, a three-way valve located in the SHW return circuit is actuated, so that storage is increased and the backup of conventional energy is not required, so that the energy saving is thereby increased.


The solar installation is monitored and regulated with the general control system for the building heating installations. This control system ensures the proper working of the installation so that maximum benefit is obtained from solar energy. To this end, it compares the temperature of the upper or outlet part of the solar collector field with the lower part of the solar storage tank, so that the electric circulation pump is not in operation when this temperature difference is less than 2ºC and is not stopped when it is higher than 7ºC. The system also acts as a means of protection against overheating or frosts, on the one hand preventing temperatures being reached higher than the maximums withstood by the component parts of the installation and, on the other, stopping the heat-carrying fluid from dropping below its freezing temperature.