More often than not, the need arises to measure the amount of energy being delivered by a solar panel, either indoors or outdoors. There is therefore a need to have efficient and reliable means of determining this energy. This paper reports in detail about the design, test and development procedures of an instrument that is capable of measuring the amount of D.C. energy delivered by a solar panel over a given period of time. It is noted that, D.C. energy meters are not yet available on the world. The instrument was developed using mostly discrete and integrated analog electronics, and it was to be incorporated into a photovoltaic system. Due to its applications, it was called a Photovoltaic Energy Recorder. In order to achieve its objectives, both the voltage and current signals from the solar panel were first multiplied to get power, then the power was integrated with respect to time so as to get energy, after which the resulting output was compared with some other preset signal. The output pulses coming out of the compared signal were then counted as fractions of energy. Each part of the circuit was tested separately so as to ascertain that it was working well before connecting the entire circuit of the instrument together. The instrument was expected to measure the instantaneous energy that the solar panels deliver. The peak power output measurement lies between 0 and 72W{sub}p. However, by changing one resistor element, it can measure any other power and energy ranges. Experimental tests have shown that it works with high accuracy of above 98% for power outputs above 5 watts. The same behavior was also noted on the amount of energy recorded by the instrument on its output device, which was an electronic counter. Test results obtained from the instrument and their analysis are given.
展开▼
