This software development was conducted using an overarching systems engineering approach from design and architecture through to verification and validation.
We overcome this issue by using a mathematical method based on the concept of equivalent time. Such model is based on empirical equations obtained from accelerated tests in laboratory.
One difficulty in applying our model to outdoor conditions arises from the fact that stress levels vary continuously according to the meteorological conditions, while our model was developed from indoor testing at constant stress conditions.
This framework is developed for grid connected systems operating in the UK climate, but it could readily be adapted for other climates with appropriate weather data.
In summary, this thesis proposes a combination of accelerated test sequence and simulations that allow to predict, for a given location, the effect of PID on the module power output.
We are confident that this methodology could be applied in general to other degradation mechanisms, thereby allowing an improvement of the prediction of photovoltaic modules reliability in different climate conditions.
In Chapter 5, this model is applied to predict the evolution of PID for devices operating outdoors, considering four locations with different climates.
Financial optimisation is identified as a challenge because current software tools facilitate optimising for maximum output or minimum cost, but do not readily optimise for minimum levelised cost of energy which is the primary objective in striving for grid parity.
In Chapter 4 we develop a lifetime model for PID. A novel method for the calculation of shaded irradiance on each cell of an array with high computational efficiency is presented.
Moreover, suitable thresholds on the weather conditions are set to properly simulate the different phases of PID. The result is a set of equations that describe the main phases of the evolution of PID as a function of the stress parameters.
Final verification of the over-arching SolaSIM framework found that it satisfied the requirements which were identified and actioned.