Regarding the Davis:
There are two separate CRC checks on the data before it hits WD making data corruption in transit extremely unlikely.
Solar is only present in 1/24 of the total data packets and yet solar is the only parameter affected. Statistically unlikely in a data corruption situation.
The spikes are very close to the full scale reading from the solar sensor that would result from the sensor output being equal to the supply voltage.
The sensor/ISS hardware has not been changed.
My conclusion is that there is a hardware problem either with the sensor, the sensor cable/connector, or in the solar measurement circuitry on the ISS.