i just recently got my system up and going and was testing the output from the sell option. I noticed the utility meter would fluctuate fast then slow and the inverters would increase amp output and lower amp output. that led me to think that i needed to smooth out the output the only way i know how to smooth out a surge like that is to use capacitors heres a link from xantrex about using pfc caps
http://www.xantrex.com/web/id/343/DocServe.aspx
and here
http://www.xantrex.com/web/id/344/DocServe.aspx
also
http://www.xantrex.com/web/id/341/DocServe.aspx
I hope this helps some people

I am not sure that adding PFC capacitors would change your meter's behavior...

If you have a lot of motors (many multiple horse power like large A/C, lots of pumping, etc.) running much of the day--adding PFC capacitors to the motors themselves (so that the caps are switched on and off with the motor) may help your Power Factor (and if your utility charges your energy rates based on poor power factors--typically only used for large factories/oil refineries and such) can reduce the current flowing through your wiring.

However, no matter your current Power Factor--the standard utility meter will not behave any different to your loads, with or without PFC caps. The utility meter only measures the "real power" used by your home/site. It does not spin any faster (and charge you any additional money) if you have poor power factor (again, unless the utility installs a PF logging meter).

Not sure why you are seeing fluctuation in your meter's disk speed--assuming that the SW is changing its output--I would suspect that this is normal (based on the SW's evaluation of the battery bank's state of charge+current solar charging conditions) and would probably not always be stable/predictable.

Otherwise, if the SW's output is way off--you may have some problems that can use Xantrex Tech support (configuration or hardware problem?).

-Bill