Hello all, Jay Ruzicka of Occidental Power (CA) was the first to submit a design that I could not find a reasonable solution that would work as smartly with available string inverters as they would with a micro-inverter design. Allan Sindelar of Positive Energy (NM), gets a runner up win, for a value equaling a case of good stout. Having been in the large commercial space for a while, it was nice of these guys to submit designs and have the discussions.
My guess would've been that folks were going to be submitting a typical 3kW residential system design with multiple planes, or shading issues, and arguments of MPPT, or reliability, or that putting a bunch of inverters behind the modules would be fine because "they" said it was ok, but what I found was definite lack of efficient, cec listed, small power inverters for these sub 2kw, and sub 1kw systems, and designers just have a lack of options in this smaller territory. Good lesson to String Inverter Manufacturers to continue to develop higher efficiency single string inverters to compete, meanwhile some seem to be bailing from this space, regarding smaller listed inverters and lower input voltages. There are literally no sub-1000's or 1100's listed with competitive efficiencies. Kaco has the 1500 at 95.5% the same as Enphase's best number. After that, there's a few other 1500's and 2000's that post 95%, 94.5% and worse. For projects in this system size territory, that is sub-2kw, where one could reason that only a few inverters behind the modules may be ok, there is a lack of alternatives. So, some of the things that would be good for string inverter manufacturers to work on to combat the micro-inverter craze, seems to be continuing in the race to bring up the efficiency of smaller units, perhaps working on multiple MPPT units, perhaps with power stages like the larger fronius units but at lower or wider voltage ranges and smaller power ratings, perhaps offering units with lower input voltage windows to accommodate shorter strings, integrating better/cheaper monitoring, or letting more people know about their existing monitoring solutions, keeping cost down, and getting them listed and approved soon. In a podcast recently @ http://www.renewableenergyworld.com/rea/news/podcast/2010/02/micro-inverters -vs-central-inverters-is-there-a-clear-winner, Raghu said that a couple hundred thousand units have been sold since 08, for the sake of discussion let's say they're 200W each and $1/Watt. That's 200,000 (x) 200 (x) $1 = $40 Million in sales... Guess I should listen to the podcast again to make sure he said that many, but if so, that's quite a chunk of change these other guys should be working for. If micro-inverter efficiency were to hold up, and installation speed could be dramatically increased, a string inverter that would compete will have to be able to accommodate shorter strings, at better efficiencies. Obviously, not ground breaking work, we've all already known that sub 2kw systems were viable candidates for micro-, but I was very disappointed to see such a lack of competition on the CEC list for those of us looking to keep our inverters out from underneath the array. Ryan ********************** _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
