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Sweden is testing a semi-truck trailer covered in 100 square meters of solar panels
(www.popsci.com)
This is a most excellent place for technology news and articles.
I would not put too much weight on that. The number of solar roadway projects and similar tech that when you run the numbers shows it being a complete waste of time - only for many different cities to invest in running a test (at their own expense) only for the project to fail later on for being too costly and not giving the benefits they were promised. Solar solutions seem to be the modern day monorail grift from the Simpsons...
This is the type of thing we should be investing in first IMO. A solar truck might make sense some day when solar is cheaper and more efficient - but we currently have a lot of static infrastructure around solar we could be building instead of these less efficient trucks (that is in terms of use of the solar cells, rather than the trust itself).