STC means laboratory test conditions that are repeatable and verifyable. PTC would be "real world" conditions. California used to publish a comparison of the two, but the link there from this page is dead.
http://www.gosolarcalifornia.ca.gov/equipment/pvmodule.phpSTC is 70F I think. Most panels output goes up if it's colder and falls when it's warmer. If you use thin film in very cold conditions you better watch the voltage carefully esp. if you use a MPPT. Don't connect more panels than 75% of the MPPT max voltage rating in a cold climate, 2/3's if you live where it might hit -40, esp if there is snow. With reflected light and cold from snow you might just push your panel's output so high you fry the controller.
In your case, with an MPPT that's rated 150v max, you couldn't string more than 3 panels anyway.. If the panels are thin film they fade worse in the heat and may not be intended for series connection. Poly and Mono panels can be stacked to give higher voltages. Over 60 volts and the NEC rules apply for wiring, 60+ is considered 'high' voltage.
Higher voltages mean lower impedance losses for a given wire size. Copper costs money, so the trend is as high a voltage as possible in commercial use. BUT, dc has a nasty arc that a/c doesn't. Breaker and disconnects for dc are different. Enphase makes a dc to ac micro converter that can be paralleled as a workaround if high voltage dc is undesirable, but the Enphase inverter costs as much as some panels, so it's a lot of extra money upfront.
If you got full rated power for 5 hours you would get 5 x 235 = 1175 watt-hours [ 1.175kwh of electricity] per day per panel. That's worth about 6.7 cents worth of grid power. You aren't going to get rich selling it back that way without the govt giving you the panel through tax cuts or forcing the utility to pay you more that they would charge you for the same electricity.
48 volt inverters do a pretty good job making 120vac if that's what you want to do with the power. But the bigger inverters have larger idle power draws so you might consider 2 inverters, one for the largest load you have and a small one for other uses. I have 2 sine inverters, a 300 watt and a 1000 watt.