[RE-wrenches] Micro-Inverter Challenge Winners Declared. Interesting details to follow.

[Ryan J LeBlanc]

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

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