Any cost advantage of central inverters might have?

The ramifications of DC arc fault protection in the newest NEC codes for P.V.? I would think that in using micro-inverters (under 70VDC and therefore not subject to DC arc fault protection guidelines) would be huge advantage to using centralized DC inverters, especially for residential installs. When and if they come up with suitable DC arc fault protection it will most likely be complex and expensive thereby negating any cost advantage central inverters might have?

I have installed both conventional and micro-inverters and for residential installs it is a 'no-brainer', micro-inverters win. Another advantage not mentioned: for ground mount systems, let's say a single axis tracker or a fixed rack that can be readily accessed from the ground, you would need fencing completely surrounding the array if you used a DC inverter, not the case with an AC micro-inverter.

According to NEC 2011, the new AFCI requirements are for DC systems above 80V and therefor N/A for micro inverters. The string inverter manufacturers are diligently working on compliance with the new standards - Gozuk included. In fact, we have several in testing around the US. While pricing is always a concern with PV systems, it is too early to tell what (if any) significant ROI impacts there will be. String inverters are typically much cheaper than micros anyway so I do not want to make any speculations on added costs.

Of course, if we all went to ungrounded PV arrays with transformerless inverters then we would significantly cut down on the chances of arc in PV systems with the built in Riso detection circuits. I am sure that will be addressed in future Code revisions.

They do have their place, they do have some advantages over string inverters but there is a lot of misinformation out there. In fact, during my webinar last week, which discussed our new SB2490 micro inverter, one gentleman sent an email asking why we are launching a new product and then trying to talk people out of buying one. Yikes! If you were not in attendance please send me your email address and I will send you the WebEx link to the seminar.

I would like some clarification on your opinion that micro inverter "win" as I am always interested in that perspective since we are launching our own this summer.