Blair,

I'm seeing a lot of efficiency numbers being thrown around lately and it
concerns me. What are you using to come up with the efficiency numbers you
have shown for the SW and GC-1000? It sounds to me you are starting with
some module spec and working back. The only way to do this is with accurate
(expensive) dc and ac measurements that are beyond the capability of most
installers. I grant you that the efficiencies my not be anywhere near the
published numbers for the SW (95% number is in stand-alone mode going into a
resistor), but it definitely not 75% on average. A good average number is
85% with peak efficiencies around 88% with the new software. The GC-1000 is
in the high 80s for average efficiency. Not sure of ST, but understand it is
similar to GC-1000.

There is no standard protocol for measuring power from an inverter. Our
company is working with Sandia on this very problem. It is a very important
issue especially given the misunderstandings generated by the manufacturers
numbers that are posted by the CEC.

Bill.