by Matt Johnson
Forecasts about the future of solar energy tend to be rosy and optimistic, but is the solar revolution really a nobody-loses scenario? A study lead by Aixue Hu (2017) titled “Impact of solar panels on global climate” addresses some infrequently mentioned concerns.
It turns out that solar energy systems have consideration-worthy regional consequences. But you may ask: why? Solar panels are not 100% efficient, they are actually fairly far from it. The most efficient solar panels on the market today run at around a 40% efficiency, with some new technologies promising around 60%, however most are much lower. A few issues arise in the conversion of solar energy into electricity. Firstly, a small percent of the solar radiation is reflected, as a result of solar panels’ glare. Then, another few percent are lost in the conversion of direct-current into alternating current and along the transmitting wires to centers of population. The authors estimate the mentioned causes to sum to about a 10% loss.
This 10% loss is part of the problem, but not all of it. Mainly, solar panels’ reflectivity as well as their solar absorption must be considered in relation to the geography they are planned to occupy. Obviously natural materials like sand and rock will have different reflectivity and absorption qualities than manmade silicon panels. Inherently, the installation of such man-made objects is going to change the characteristics in the region of installation. Interestingly enough, the article states that “In general, the changes in the reflected solar radiation do not directly affect the regional and global climate, but the changes in absorbed solar radiation do”. A decrease in overall solar absorption resulting from the addition of solar panels leads to a local cooling effect of around 2°C.
In other regional studies, the results varied. For an Egypt installation, precipitation would be reduced by over 20%, while installations in other regions would increase precipitation. A solar array installed in western North America could increase precipitation by a few inches, for instance. This affects plant life which affects leaf size and therefore transpiration: this in and of itself has effects on the temperature in an area.
The message gathered from this study is that solar arrays have consideration-worthy consequences in most regions of the globe. While solar arrays in some areas may provide consequential benefits, they may have repercussions in others. These consequences, good or bad, must be considered and acknowledged. Luckily, the authors report that overall, “the potential global mean climate changes induced by the use of solar panels are small in comparison to the expected climate change owing to fossil fuel consumption”.
Hu, A., Levis, S., Meehl, G.A., Han, W., Washington, W.M., Oleson, K.W., van Ruijven, B.J., He, M. and Strand, W.G., 2016. Impact of solar panels on global climate. Nature Climate Change, 6(3), pp.290-294.