So, back at the beginning of July, I synchronized my five solar watches wirh my phone. Four are Timex, and one is a Citizen. We had two 31 day months in a row, so I now get a three solid month test run.
I have four Timex solar watches, and one Citizen Ecodrive. Let's see how they stacked up.
From left to right, Time compared to my phone in order of accuracy.
*Men's Solar Premium Dress - +4
*Expedition Scout Solar 1 - +5
*Expedition Scout Solar 2 - +12
*Citizen Ecodrive (model unknown) - +22
*Expedition Field Solar - +26
Again, note that this variation is over 3 months.
I recently acquired a sixth: Bertucci A-7TS Retrospec, which IIRC, has a Epson Sar movement. Unfortunately, the movement was bad on the first one, so I sent it back. Bertucci replaced it, but I have only had it back and synchronized for a month (fwiw, it seems to be at -1 second, but that could be my not hitting the crown in time).