The solar panel generates a nominal 60 watts of electricity but does not produce high voltage. The maximum output possible is 27 volts and maximum current of 3.6 Amps. This is under optimal conditions.
Voltage is generated when the solar panel is exposed to sunlight the output wire maybe energized even after the vehicle is shut off and the 12 volt auxiliary battery is disconnected. Current will only flow if the solar ventilation blower fan circuit is turned on.
The solar panel is located on the roof above the rear passenger space above. The solar panel output wire is not electrically connected to the 12 volt auxiliary battery, SRS airbags, or the High Voltage battery pack. The solar panel output will not back feed power to these circuits.
Breaking or cutting the solar panel is generally not a hazard except for injury that may occur from material fragments.
The Solar Panel Ventilation System only powers the fan but the Remote Air Conditioning System activates the A/C compressor is powered by the high voltage system. This is important to remember. However, the Remote Air Conditioning System only operates for 3 minutes and then the high voltage battery cables are de-energized because the high voltage flow from the HV battery pack stops.
For more information read pages 13 & 14 in the 2010 Toyota Prius (3rd generation) Emergency Response Guide.