direct utilization: 6.4 kWh (58%) power to utility: 23.3 kWh (212%) power from utility: 4.6 kWh (42%) (percentage values related to the requirement). As expected the result is not as positive when drawing up the balance for an average winter day (Fig. 3): requirement: 11.0 kWh (100%) generation: 1.1 kWh (10%) direct utilization: 1.0 kWh (9%) power to utility: 0.1 kWh (1%) power from utility: 10.0 kWh (91%) The midday load peak may be reduced due to the utilization of the diffuse share of the radiation; the evening load peak, however, does not change. If one now draws up the balance for a whole year, with an hourly simulation, the following values would be achieved (related to 5 kWp, 10% total efficiency of the system) (Fig. 4): requirement: 4000 kWh/« (100%) generation: 5000 kWh/u (125%) direct utilization: 1500 kWh/u (38%) power to utility: 3500 kWh/« (87%) power from utility: 2500 kWh/« (62%) Taking into account these values concerning power consumption, solar cell area, and total efficiency, the consumer could generate nearly 40% of his power requirement and furthermore still feed an amount of energy corresponding to nearly 90% of his power requirement into the grid. Effec ts on the Power Generating System Up to now only an example of one normal household was considered. In fact there is within a supply area a mixture of power requirements comprising industry, trade, agricultural businesses and households. How do the changed load curves of the households equipped with photovoltaic plants influence the load duration curve of the total supply area? Figure 5 shows the grid load in the Federal Republic of Germany on the day of the peak load divided into base-, medium-, and peak-load range. If we remain with our example that 1 million single- and two-family houses in the Federal Republic of Germany are equipped with a 5 kWp photovoltaic system each, the two most important questions are 1. Is it possible to avoid through such systems the additional construction of conventional power plant capacity? 2. To which extent does the generation based on the remaining amount change? Figure 6 illustrates the results of a simulation on an hourly basis with solar radiation data of the particularly favourable solar year 1976 and load data of the Federal Republic of Germany from 1980. For each month load peaks and energy quantities for the original curve and for the
RkJQdWJsaXNoZXIy MTU5NjU0Mg==