US versus DE installation costs [RE-wrenches]

[John Berdner]

Wrenches:

I sent an email to Germany asking for some more information from the
guys at Photon. A few things to note about installation costs in
Germany.  They have much lower installation costs for several reasons,
including:

- No "really expensive and totally unnecessary" dc disconnect switch
required. Just use the MC connectors on the inverter which are not
allowed here because somehow having them on the inverter is different
than having them on the back of the array. Hmmm....

- No conduit required between array and inverter. Just use the same
double insulated, sunlight resistant, wire you use on the back of
modules but that you can't use here because ?? (see above)

- No ridiculously oversized dc grounding electrode conductors because
they don't ground the PV negative to compensate for a problem that does
not exist anymore and even if it did still exist they have ground fault
detectors that will find it at personnel protection levels instead of
the "fire protection levels" we use here in the US which are not defined
anywhere but certainly WILL kill you deader than a doornail and then
after you're dead unground the array because we all know that ungrounded
PV is safer in the first place. 

- No "really expensive and totally unnecessary" ac disconnect switch
only required to avoid a turf war between utility meter readers and
troublemen.  In Germany they just use the circuit breaker in the sub
panel, or the main breaker at the house.  Yes, Scarlet, these are the
same circuit breakers that are rated as disconnects and we depend on
every day to provide the fundamental level of electrical protection but
somehow won't work in the incredibly unlikely event the inverter's
anti-islanding circuitry does not work.  Assuming all the other stuff
miraculously fails simultaneously (which has about the same likelihood
as being hit by lightning three times in one day) you can just pull the
meter which probably wont even inconvenience anyone because, when you
think about it, the utility is down and that is why the linemen wants to
disconnect the system in the first place.  Of course if you ask any
lineman they will tell you they have procedures that make the disconnect
unnecessary (like not ASS U ME ing the line is dead and shorting the
line before they work on it) and then they will tell you they would
never take the time to go around and throw the switches during an outage
presuming they even knew where these switches were located, which they
don't.

- No conduits required between the inverter and the ac panel. Just use
the watertight connector that plugs into the inverter and the sunlight
resistant jacketed cable to wire directly into the sub panel.   

Now a disclaimer: 
I have just come back from a Standards meeting where otherwise
intelligent people will tell you all day long that these requirements
make perfect sense because that is how we have always done it.  Perhaps
my reasoning is a bit clouded as a result of my recent extended exposure
into this way of thinking.  I gotta go.  

Happy holidays to all!
 
Best Regards,

John Berdner



-----Original Message-----
From: Joel Davidson [mailto:joeldavidson at earthlink.net] 
Sent: Friday, April 18, 2003 02:42 PM
To: RE-wrenches at topica.com
Subject: Turnkey PV for $7/W DC or AC? [RE-wrenches]

March 2003 Photon International magazine reported $6 per watt or less
for a turnkey PV system in Germany. The April issue reports the results
of a survey of 87 German installers and 232 PV system packages. A
completely installed 2 kW system, including modules, inverter, mounting
hardware and wiring, costs on average $14,040 after a 16% value-added
tax. 70% of the turnkey systems cost $5.40 to $7.02 per watt.
Installation costs range between $0.255 to $1.80 per watt. The survey
only included up to 5 kW system because residential rooftop PV systems
rarely exceed this size in Germany.

Two questions:
1) Are these system ratings DC STC watts or AC watts?
2) If AC watts, how are AC watts calculated?

Thanks in advance for any feedback from wrenches in Europe.

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