For the generator the most important characteristics are efficiency, cost and weight. A generator with an efficiency over 80% is needed. The generator must also be able to have a constant voltage output to charge the batteries during fluctuations in solar thermal power.
One solution would be to use several car alternators. These are very inexpensive used but only produce a maximum of 1000 watts but the biggest problem with Alternators are their low efficiency between 50-70%. For the solar car at least two if not 3 alternators would be needed. Alternators are very useful because the torque need to rotate them can be changed by applying less power to the magnet coils. In this way the same voltage can always be produced at the same speed and only the amps will drop with reduced solar thermal power. This feature can also be used to run at the steam turbine speed with the highest efficiency.
I am still searching for a Generator that is over 80% efficiency and can be used to charge my battery bank. The power output would have to be between 1000-3000 watts.