expanding grid tied PV array

[oxide23]

I am expanding my 1.1 kW system to a 2.0 kW system. I found exact matching panels and my inverter checked out to go to 2.0kW.

My existing panels are in series. I was planning (DIY) on adding the new ones to that chain and just increasing the voltage. From what I understand, I can just rack them and add them to the string. Does anyone out there have any advice or some common mistakes people make when doing this? i.e. Do you have to change a setting on the inverter or does the inverter just handle it? Is it this simple or am I missing something?

thank you

[Mike90250]

You need to go to the inverters mfg page, and use the "String Sizer Caculator" tool, and make sure you don't over voltage the inverter.
you will either A) add panels in series, and be very close to the max voltage or B) have to break the existing string, and wire 2 parallel strings to the inverter, being sure you are above the minimum MPPT voltage in hot weather.

And get several thick blankets or tarps. Or work at night. You will have HIGH VOLTAGE DC at the wires, and no way to turn it off, except throw a blanket over it.

You may need the MC disconnect tool for the connectors.

[oxide23]

Thanks Mike. My inverter is a Selectria PV 1800, from the manual, it references my exact panels and says you can connect 11 modules for optimal performance based on average temperatures here in New England. So my plan is to add the panels in series. I'm hoping that the contractor that help me set the original array used a large enough gauge wire from the junction box from the roof to the DC shutoff on the board in the basement. I have to get the racks up there first, so the panels are going up another weekend. I'm definitely going to be covering these things up during install, I hadn't thought of that, thanks. -Jonathan

[Mike90250]

Since you are wireing in series, the amps, and the wire gauge, will stay the same, the voltage will increase. Be sure the voltage of 11 panels in series, in COLD weather, is below the kill voltage of your inverter.