Nice article. Shocking BBC photo - if the panels were powering one computer. It would seem that they're not, and in fact most of the energy is for use in heating, cooking, etc.
The SOLO was an excellent project, and I'd still love to see it succeed. Given the fact that PC laptop hardware seems to be more energy-efficient than any ARM-based RISC OS hardware, perhaps SOLO should move away from RISC OS entirely? Unless, of course, RISCOS Ltd &/or Castle want to get involved.