Hi,
I have a mppt smart solar 100/50 charge controller. I have 4-25watt hooked up in parallel. Im seeing my trend graph constantly fluctuate between 13 volts and back up to 19 volts. Nominal output voltage is near 22 volts. My amps hardly go above 3.5 amps. Nominal amps are 6.8 for specs. 
I really believe when you put this all your panels in series the result will be much better.
When you put all in series the PV voltage may not be more then 100 Volt.
When the voltage from the PV is higher, the MPPT will work much better.
The MPPT must see a PV voltage 5V high then the battery voltage.
So I think the graph you see is correct.
regards, Rob
