DC kWh meter [RE-wrenches]

[John Berdner]

Randy:
 
You could capture the DC voltage and current with Sunny Data and then
post process the data in Excel to get dc energy (kWh).  From there you
can estimate the inverter efficiency.  The problem with this is that the
dc current is a calculated value in the inverter so you have to consider
the error stack which might make your number essentially meaningless,
i.e. 93.326% +/- 5%.    Inverter efficiency is difficult to measure
under any conditions and usually requires and AC power analyzer to get
any real accuracy.   Trying to estimate it using kWh on both sides will
probably lead to bogus results.  
 
Best REgards,
 
John Berdner


>>> jay at asis.com 2/2/2004 05:51:14 PM >>>
Hi Randy,

Well if its a utility then they have the money to make it work.

Talk to john Berdner at SMA, heck the SMA already has an meter in it,
maybe
that can be the base for the info with their software??

jay


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