Limitations of simulations
Simulations are powerful tools for process design offering a number of advantages as outlined in the previous sections. However, there are limits to their use. For example, it is easy to make mistakes, such as, assume erroneous constants and neglect factors, which may be important. Like other engineering calculations, a high level of skill and scientific judgement is required in order to produce correct and useful results.
It is possible to model a system to a high degree of accuracy in order to extract the required information. In practice, however, it may be difficult to represent in detail some of the phenomena occurring in real systems. Additionally, physical world problems such as, leaks, plugged or restricted pipes, scale on heat exchangers, failure of controllers, poor installation of collectors and other equipment, poor insulation, etc. cannot be easily modelled or accounted for. Simulation programs are dealing only with thermal processes but mechanical and other considerations can also affect the thermal performance of solar systems.
There is no substitute to carefully executed experiments. A combination of simulation and physical experiments can lead to better systems and better understanding of how processes work. These can reveal whether or not theory is
adequate and where difficulties are present in the design and/or operation of the systems. As a conclusion, simulations are powerful tools for the modelling, design, prediction of performance and research and development. They must, however, be used with care and skill.
No study of solar systems is complete unless an economic analysis is carried out. For this purpose a life cycle analysis is usually performed as explained briefly in the following section.