Example 2 The capacity of 5000 MW corresponds to the capacity of the “reference”-concept of “solar power satellites,” as proposed by the DOE and the NASA as study basis for research of extraterrestrial energy transducers. With this reference concept the following assumptions were taken: solar cell area: 52 km2 cell material: silicon efficiency of cells: 14% location: geostationary orbit (i.e., 36,000 km orbit) energy transmission: microwaves receiver antenna area: 100 km2 system efficiency: 7% Through these two examples, which are already of energy-economical importance due to their size, the problems of terrestrial and extraterrestrial use of solar cells will be briefly discussed. WHAT ARE THE EFFECTS OF TERRESTRIAL DECENTRAL APPLICATION OF PHOTOVOLTAIC SYSTEMS? An essential feature of the electricity supply is that the consumer and not the power utilities determine the amount of electric power supplied and — based on physical laws — generated in the same moment, as electric power cannot be stored. This is an essential difference between the power economy and all other branches. Effects of an Individual Facility The power requirements of individual consumers, such as households, trade, industry, etc., are very different during the course of the day, the week, and the year. Figure 1 shows the load curve of a 5-person-household with complete electrical equipment during a working day, i.e., a household with the usual electric appliances and electric hot water storage. Typical are the load peaks after getting up, during the cooking, and in the evening hours. The load curve of a normal household does show certain differences between a summer and a winter working day; these, however, have not been considered in order to simplify the following thoughts and as the principle evidence would not be altered. If one now compares this load curve with the generation of a 5 kWp solar generator the result would be different due to the seasonal amount of solar energy depending on the time of the year. In the course of an outstandingly nice summer day in July (Fig. 2) the generation of the photovoltaic roof exceeds the requirement during the time between 5 a.m. and 6 p.m. considerably and even the evening load peak will be reduced. If one now draws up the consumption and generation balance, the following result would be shown: requirement: 11.0 kWh (100%) generation: 29.7 kWh (270%)
RkJQdWJsaXNoZXIy MTU5NjU0Mg==