Aussie240 found the reason for the voltage.
They did make a list of all common (and not so common) types of equipment and appliances only to find that none will work. This wasn't enough to deter them. The authors believe that going from 230VAC to 350VDC will be easier than from 230VAC to 230VDC simply because more and more equipment contain switch mode power supplies.
About the only thing they found to be tested for this use were wires and fuses.
