Interconnection info request [RE-wrenches]

Matt Lafferty mlafferty at universalenergies.com
Thu Mar 11 08:29:07 PST 2004


Allan S wrote:

> The issue I want to protest is a requirement that "the qualifying
> facility to be designed by an engineer licensed in NM." Nobody
> else requires this, and it would add several hundred bucks to the
> system cost.

Allan:

I would request clarification of the requirement... Do they mean Civil,
Structural, or Electrical engineering?  The language sounds eerily
familiar... Traditional "utility speak".... "Qualifying facility".... It
sounds to me that they are "broad-brushing" all interconnected
generation with the same requirements for a larger generator, generally
interconnected at 4.6kV or above.  Most of these generators also utilize
"rotating machinery", which adds a whole layer of design and protection
considerations.  The complexities of larger generation facilities,
including not only the Power side, but the Protection and Construction
sides as well, deserve to be engineered.  Also, look out for language
that refers to telemetry, remote monitoring or control, "dedicated phone
line", etc.  If they are just "copy-pasting" from their standard
Generator Interconnection Guidelines, they will more than likely just
copy-paste the whole danged thing and put a new title and date on the
cover!

They don't get it that these are very small systems by their standards,
and are interconnected at service voltage.  These are inverter based,
operating at unity power factor, with listed protection systems built
in.  Much if not all of the power produced is consumed on-site, as
opposed to being a 100MW CoGen plant sitting out in a field with no
significant site loads.



Back to our "little systems".  Civil or Structural engineering may seem
reasonable, situation dependent... Civil for ground-mounts, Structural
evaluation of roof-structure for roof-mounted, etc.  Electrical
engineering is an entirely different thing.  I would argue for a
"size-dependent" exemption for PV or Wind systems that is defined
something like this:

1) Inverters / PCS equipment must be listed for their application...
i.e. UL 1741
2) Inverters / PCS equipment must be IEEE 929 compliant
3) Interconnection voltage is <600 Volts
4) Line amperage is <800 Amps
5) System voltage is <600 Volts (AC & DC)
6) System amperage is <800 Amps (AC & DC)
7) Entire system must be permitted, inspected, and approved by the local
AHJ prior to interconnection.
8) Utility Disconnect is "Approved" and located per the most flexible
guidelines you can negotiate!  (Hey, it's not unreasonable to install it
in the neighbor's back pasture or across the road, is it?  LOL)

These requirements are consistent with widely accepted practices, here
in California anyway.  The premise is that a Contractor is deemed
"qualified" to design and install electrical systems that do not exceed
600 Volts or 800 Amps without an engineer's stamp.  Building inspectors
are deemed "qualified" to inspect such systems without referring to an
engineered set of drawings. 

I would support my argument with a nice stack of sample 1-line drawings,
equipment specs & installation manuals (with "protection setpoints and
specs" highlighted), and DONUTS!  1-lines should indicate equipment
brands & models, system voltages, amperages and kW (AC & DC).  A couple
of examples of multi-inverter systems is recommended.  Donuts should be
mixed... 25% Jelly minimum!  Don't forget to smile!  

Your message is: "These are safe, simple, small.  Our equipment has all
the built-in safety stuff you require for large generators, just scaled
down to fit in this little box here.  Would you care for another donut?"

The thing they are "concerned about" really boils down to "what happens
at the interconnection and what does it look like?".  Power quality,
hi-lo voltage & frequency protection, operating amperage, short-circuit
amperages, anti-islanding protection, "where is "our" switch?", etc.
Between the inverter specs and 1-lines, this should be satisfactory to a
reasonable person.....   Errrrrr.... Did I say "reasonable"?  It might
be prudent to haul an inverter or two over there with with you so they
can see "what's under the hood" for themselves.  If there is a local
site with a system operating, maybe you could take them over there and
demonstrate the anti-islanding by putting a Voltmeter on the breaker
then turning the breaker off.  
   
Remember: To the utilities, we're like little pimples all over their
hind end!  Do not forget the donuts!

Best of luck.  I hope some of this helps.

Matt Lafferty
Universal Energies Institute
mlafferty at universalenergies.com
(916) 422-9772
(916) 628-7694 Cell
(916) 914-2247 Fax
www.universalenergies.com

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