I purchased 2 Fronius Primo 10.0-1 grid-tie inverters for my residential solar project. I plan to deliver 3 strings of 7 panels each (Sunpower 435W, 5.97A, 72.9Vmp, 85.6Voc) to one inverter, and 4 strings of 7 panels to the other inverter. Each inverter will then receive maximum 673V (calculation based on Voc + temperature correction for the coldest date on record in my area) with one inverter receiving roughly 18A and the other roughly 24A of DC current. The Primo inverters are rated up to 1000V so that shouldn't be a problem... The Primo inverter installation manuals state that they can be wired in parallel, but it doesn't go into details on how one would actually make the connections. From my inverters I will run the 240V output wires to an AC disconnect box, and from there to the meter (the local utility company will be replacing my current meter with one that is capable of metering both directions). If I were going with a smaller system and just one inverter, my understanding is that I would just wire directly from the inverter to the AC disconnect. Pretty simple. But with 2 inverters, I have been told that I need to run each set of inverter outputs to a subpanel/load center with 2 60A breakers first, and then on to the AC disconnect. Does this sound correct? And if so, won't the distribution be wired "backward" from the normal flow pattern? meaning, I would have to wire each inverter into the "load" side of the breakers, then the single "output" from that load center would be going "out" the top 2 hot L1/L2 lines and from there over to the AC disconnect? Is that a problem with electricity "flow" going backwards thru a breaker? I am planning to have a licensed electrician do this work for me just for safety, but I enjoy learning about this stuff so I am trying to understand what all is involved beforehand.... I know the Fronius manual says that the inverters need to be "linked" to each other with a shielded Cat5 cable - it sounds like this is how they communicate with each other, and it looks pretty straightforward to make that connection.
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