I'm currently designing solar panels for a lunar rover MSc project. Two options of the solar panel are being considered, 1) The solar cells are directly mounted to the rover body however the maximum space available is around 0.66m2, constraining power production but less mass of mounting/structure supports 2) A panel made up of solar cells is mounted slightly away from the body but in the same orientation, this would allow for a bigger size however increased mass for the construction of the panel and the mount structure. I'm asking for opinions on how to trade these methods off and the typical masses to expect, currently the bare solar masses is below 1kg for sizes around 1m2 and under. Thanks!
Dear Shannon Mutch
welcome,
wish you success in designing and constructing you panel.
I think you can use the a hybrid solution. That is to mount the solar cells on the body of the rover and make an extension aluminum plate which is oxidized to mount on it the rest of required solar cell array.
Since there is no rain then you must can construct the encapsulation from sheets of glass covering the solar cells without cementing them to the cells.
The most important thing that you support the cells protecting them from the environment with the minimum weight and highest strength.
I think you you can satisfy the weight budget of the PV array.
I would like to introduce the encapsulation ideas for terrestrial panels but they will be mounted in desert.
You may find some inspiration in them: Article A.A. Elshazly, A. Zekry , M.A. El-Koosy and M.s. Farid, “Thr...
and
Article M.S. Farid, A Zekry, A.A. El-Shazly, and M.A. El-Koosy, “Eva...
Best wishes
Dear Shannon Mutch
welcome,
wish you success in designing and constructing you panel.
I think you can use the a hybrid solution. That is to mount the solar cells on the body of the rover and make an extension aluminum plate which is oxidized to mount on it the rest of required solar cell array.
Since there is no rain then you must can construct the encapsulation from sheets of glass covering the solar cells without cementing them to the cells.
The most important thing that you support the cells protecting them from the environment with the minimum weight and highest strength.
I think you you can satisfy the weight budget of the PV array.
I would like to introduce the encapsulation ideas for terrestrial panels but they will be mounted in desert.
You may find some inspiration in them: Article A.A. Elshazly, A. Zekry , M.A. El-Koosy and M.s. Farid, “Thr...
and
Article M.S. Farid, A Zekry, A.A. El-Shazly, and M.A. El-Koosy, “Eva...
Best wishes
Abdelhalim abdelnaby Zekry Thank you very much for your useful response.
Dear Shannon,
Best of luck for your design. I think you should design your solar panel like an umbrella which can extend its arms (panels) to flat and there should be a solar tracker so that it can move accordingly for getting maximum power. Hope you understand.
Hi Gourab Das , thank you for your response. The problem we face is going to the poles puts constraints on the sun position as it only rises 1.5 degrees over the horizon and so its likely that the optimum position for solar panels is on the side of the rover to catch the low solar rays. What is the orientation of the umbrella shape you are suggesting?
Can i also ask if people are aware of the likely decrease in efficiency of Spectrolab 29.5% XTJ cells as the temperature fluctuates from the optimum operating range? I have read that for most mono and poly types is is around -0.5% per 1 degree, does this likely apply for space rated cells?
Dear Shannon,
Spectrolab’s XTJ cells are well used for space applications and there is very less amount of temperature induced degradation reported. But yes mono and poly crystalline Si solar cell degrades with the rise of temperature at the range you have mentioned.
Dear Shannon,
I’m not convinced that Sun rise only 1.5 degree over the horizon in the moon. However you can design the umbrella like solar panel which can move its position in 3D according to the Sun’s position. If it is not possible to design like that as it is quite complicated you go with the flat panel but mount it on carbon fibre for weight management and there should be a setup so that panel can go both the side of the rover. Of course this setup also need an solar tracker to get maximum power of it.
Hello Shannon,
One thing to keep in mind is that multijunction cells like the XTJ have a solar angle of indigence dependence which can reduce your efficiency if the incidence light is not normal to the front surface. The subcell thicknesses are designed for incident light, so off-angle incidence will increase the light's path length through the cells, resulting in inefficient photon extraction. It is not a huge loss, as noted by Spectrolab in the attached, but if you are designing you system to power your rover precisely, it may be of substantial consideration.
For this reason, and especially if you are near the poles (where sunlight will move 360° daily), I would recommend a tracking mount. If you are near the poles, you would really only need one rotational axis and should not need to adjust pitch much.
https://www.spectrolab.com/pv/support/Energy_Production_from_High-Efficiency_5-Junction_Concentrator_Solar_Cells.PDF
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