I am considering an addition to my present system. Now I have 1800 watts and Sunny Boy inverter. Grid tie. Working good and on a tracker.

I wish to increase my array. Thinking about Evergreen panels, removing my present panels from the tracker and put Evergreens on the tracker, say about 2880 watts. 16-180 watts. I wish to put the present 1800 watts on a fixed pole or ground and then the 2880 on the tracker, and preplace the Sonny Boy with a larger inverter.
My question, is this the best idea? or should I simply add another inverter of sufficient size(2880) and run two inverters to the grid?
I wouls appreciate your differing ideas.
Thanks,
Dave O

Dave,

It is probably a wash technically... You can put panels sets (say 10x32 volt panels) on an east roof, and another 10x32 on a west roof, and then parallel the two strings together into one inverter and as long as all of the inverter ratings are met--will work very nicely and only a point or two off of optimum efficiency.

Just to be clear--you want the entire string of 10 panels that share a roof direction to be connected in series together... You do not want to have 5 panels from the west in series with 5 panels on the east roof in one series string--that will dramatically reduce power output (basically, the panel Vmp voltage is similar on east/west roof lines (once the panels have sun)--but the current is directly proportional to amount of sun light..). So the reduced sunlight on one plane will reduce the overall current of the whole string.

From what I have seen, 3kW GT inverters (and above) seem to be pretty competitively priced (close to $0.50 per watt or a bit more, the smaller inverters can be $1.00 per watt).

So, I would go back and ask some other questions... Like, do you want to monitor the inverter's power output? Getting a new, larger unit, or a compatible smaller unit with the first inverter--which give you the monitoring functions you want. (Xantrex, GT family, for example, can daisy chain multiple inverters together and all be read with one computer interface--IIRC).

The other option would be--are you interested in off-grid for backups/emergencies? Perhaps you can backup or redo your system with an Xantrex XW GT/Off-Grid compatible system...

(Personally, I use a small Honda eu2000i generator for my emergency backup--power is very stable where I live and the batteries are, currently, just not worth the investment for a once in 50 year five-day-grid-failure).

In the end, probably just run the costs out for the several options and see which gives you the best bang for the buck and meets your requirements.

-Bill

Thanks Bill, You give me good food for thought.
Dave