To obtain low-cost solar radiation sensors with energy applications, small commercial photovoltaic cells have been adapted. With the purpose to evaluate the resulting thermal drifts, a temperature sensor has been connected to a small electronic circuit. The calibration curve provided by the cells supplier is not useful in this case because it is made for a constant 20ºC temperature. Besides, the additional circuit also affects the results. This work presents not only the design and implementation of the additional elements, together with the data acquisition system, but also the results of the calibration work, the fitting of new incident solar radiation functions regarding the temperature of the cell and the intensity of the resulting current, besides the validation of the results for four of these cells.

The potential of absorption machines to cool, in particular, in house air-conditioning systems is well-known. Using solar thermal energy helps decreasing air-conditioning systems CO 2 emissions. The purpose of this work is to prove the effectiveness of this kind of systems to cool an average house during summertime. The setting uses an unit heater for heat dissipation. The cooling coil decreases the COP setting because the dissipation depends on external temperature. Using another renewable source of energy, like geothermal energy (Ground Source Heat Pump, GSHP), would improve the performance of the setting because, from a certain depth, ground temperature is practically constant and it is lower. The goal of this article is to present the design of the system as well as some first results for several representative days in August 2009.