For solar energy in the past, achieving as low a ‘cost per watt peak’ as possible was important. Solar cells and panels were optimised to generate as much power as possible at as low a cost as possible under ideal conditions (i.e. under standardised light tests).
Now, as we move towards a smart electricity grid, we are also seeing a major shift in attitude: the cost per watt peak is no longer the central issue; instead it is the actual cost per kilowatt hour. In other words, our solar cells and panels must be able to produce as much energy as possible under real, local conditions.
In response to this trend, we realised a simulation environment this year that makes it possible to predict and optimise the energy yield from solar cells and panels.
The model is made up of two components. On the one hand, we are able to predict the energy yield under variable weather conditions. The light incidence, average temperature and wind speed passing over a solar panel vary from location to location, as well as from country to country, and from moment to moment.
Our model enables us to predict very accurately and in the very short term (hours, minutes, even seconds) exactly how much electricity a certain type of solar cell will produce under particular circumstances (wind direction, wind speed, temperature, clouds, etc.). Being able to forecast the actual production of electricity is one of the major factors for keeping the energy network stable.
Another component of the model enables us to carry out technology optimisation loops, or ‘what if’ analyses. By ‘playing’ with various technology parameters, we are able to make the right technology choices. For example: what is the effect on the energy yield if I apply thinner glass to the front of my solar cell? What happens if I incorporate a different or a thinner encapsulation layer?
We can only maximise the energy yield if we work with the best solar cells. Which is why it remains important to continue increasing the performance of individual solar cell technologies (Si PV, organic PV, etc.) in the ‘classic’ manner.
For example, by producing solar cells whose efficiency exceeds the limits of crystalline Si solar cells. Imec also achieved record efficiencies in 2015, both for n-PERT solar cells (recording as much as 22.5% for a 6-inch solar cell) and for perovskite solar cell modules (13% conversion efficiency).
We also combine the best of both worlds, by stacking perovskite-based solar cells on top of a conventional Si solar cell. Efficiencies in excess of 30% should be possible with this tandem configuration.