Solar simulation
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Systems for the use of solar energy , i.e. photovoltaic systems as well as solar thermal systems , work in complex contexts. Many factors have an influence on the technical functionality and profitability .
Simulation of the efficiency of solar systems on the computer using calculation models
Calculation methods and computer programs for determining the efficiency of energy generation with solar systems accompany the development of solar technology from the development and construction phase to the installation of the system. They help you find answers to questions such as the following:
- How disadvantageous is a plant location in the north compared to the south?
- What influence does the alignment of the solar modules or collectors have ?
- Which slope is optimal?
- How does the shadow cast by parts of the building, trees, etc. Ä. out? ( Shading analysis )
A solar system must be designed from the outset so that it works as economically as possible and provides the required performance. A critical analysis of the efficiency and effectiveness of the individual system components is of great importance for manufacturers, system builders and users.
Solar simulation programs work with time step simulation; d. In other words, they calculate the system status and energy sums at intervals of a few minutes.
For a correct simulation calculation, the data of the solar radiation and the outside temperature, formulas for the calculation of the position of the sun and information on the efficiency of the individual system components, e.g. B. Collector or solar module, heat exchanger or inverter necessary. Furthermore, in solar thermal simulation programs, the simulation of the solar heat storage tank is of central importance: Since warm water is lighter than cold water, it rises in the solar storage tank (typical temperature values in a solar storage tank range from 10 ° C (below) to over 90 ° C (above) )). If the storage tank is not precisely reproduced using simulation technology, the collector yields cannot be calculated precisely either, since the collector yield is heavily dependent on the collector operating temperature. The collector operating temperature, in turn, is very much dependent on the temperature of the water that is pumped from the solar storage tank into the collector.
The achievable degrees of efficiency depend on the intensity of solar radiation and the system temperatures (also with photovoltaics) and are specified as "SFi" (solar coverage). In the case of solar thermal systems, the efficiency levels can fluctuate greatly over the year, as a collector has to be hotter than the storage tank or consumer before it can even deliver energy to it. System states in which a collector has to switch to "stagnation mode" because the heat storage tank has reached the maximum temperature must be taken into account.
In the case of stand- alone photovoltaic systems (with energy storage ), simulation programs can calculate the charging and discharging processes in advance in a similar way and thus help to dimension the PV modules and the accumulator correctly.
The problem of excess solar energy does not exist for grid-connected photovoltaic systems. The efficiency of the components depends practically only on the irradiation and temperature data. With regard to the feed-in tariffs that can be achieved (in Germany according to the Renewable Energy Sources Act ) and the associated returns, precise yield forecasts are also of interest for this type of system.
Simulation of solar radiation by means of a test arrangement with artificial light and heat sources
The term “solar simulation” is also used in connection with the simulation of solar radiation through artificial light and heat sources. These simulations are used for measuring stands in closed rooms, for determining the efficiency of solar collectors or PV modules , but also for testing materials for aging under UV and temperature influences.