In our second research webinar, we share our progress in the exciting novel area of solar cells for aerospace applications. Dr Wing Chung Tsoi, our Organic Photovoltaics and Perovskites Lead gives an overview of the work of his team. Dr Harrison Lee discusses the High Altitude Pseudo Satellites (HAPS) applications while PhD student Declan Hughes will cover space applications. Watch it to find out more…
But what else did you want to know? Here are the questions asked by webinar attendees, answered by Chung and the team.
1. What efficiency do AM0 have in the climb phase to the HAPS altitude?
The AM0 is mainly occur at high attitude. The state-of-the-art solar cells should have AM0 power conversion efficiency for HAPS of around 30%, but the cost of production is very expensive.
2. Do you have to consider repairability in space applications? Or is it just a case of replacing if anything breaks?
For real space applications, it is very unlikely the solar cells can be repaired. For HAPS, it could be possible to replace the non-functioning solar cells with fresh solar cells when the HAPS return to the ground level.
3. Have you performed simple system level calculations on a HAPS platform, e.g Zephyr, to determine the minimum required cell efficiency?
Not really. Our first step is to test its power conversion efficiency and stability under mimic HAPS environment to see if it’s feasible to go further. Now, it looks like it would be good to consider more practical issues.
4. In terms of materials used to manufacture the modules, have you considered if any of the components used are scarce or too expensive for commercial deployment? And how much will you need to reach that stage?
One of the main motivations for exploring perovskite solar cells for HAPS (and real space applications) is that it could be fabricated by low-cost mass manufacturing methods. The most expensive components should be the gold electrode, ITO electrode if they are used, and also the top electrode deposition need to be more scalable. We are not at the stage of calculating the cost requirement but believe it could be very low-cost compared with inorganic solar cells. At certain point, it would be good to calculate it.
5. Have you looked at CuSCN instead of Spiro-OMeTAD?
Early on in my research I looked at using CuSCN to replace Spiro-OMeTAD in my devices. However, due to ion migration from the CuSCN to the metal electrodes and the perovskite, capping layers are needed to improve performance and stability. This proved difficult to reproduce and results without them were lacking. But if good device performance was achieved, then it could be a good replacement for the Spiro HTL.
6. How flexible can photovoltaic (PV) solar cells be, from a structural aspect?
The other main motivation for perovskite solar cells for HAPS (particularly for real-space applications) is its ultra-high flexibility because they can be fabricated on flexible substrates and they themselves are also very flexible. It is found that they should be much more flexible than normal inorganic solar cells.
7. Do the PV substrates form part of the HAPS wing skin or are they attached to an existing skin?
They are attached to an existing skin.
8. Is the conventional encapsulation required at ground level for things like UV for example, are they likely to be the same demanding encapsulation requirements in a HAPS environment?
For ground level, oxygen and humidity should be more important issue. For high altitude, UV will be more important, as the UV level of AM0 is about double that on the ground level.
If you have any further questions, please get in touch, we’d love to hear from you.
We would like to thank Airbus Endeavr Wales for the financial support and Airbus technology for their contribution and support.