Hybrid Car – More Fun with Less Gas

PV Panels $.98/Watt? - Page 3

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Posted by vaughn on September 24, 2009, 12:59 am

That's pretty impressive.  We do about the same in the Palm Beach area, (no
pool pump, gas hot water) but we do it by only using our whole-house AC a
few hours per day.  At night we run a little mini-split in the bedroom, and
during the heat of the day we run a single high-efficiency window unit to
cool only the den.

Some day we will replace our central unit with inverter technology, but
probably not until the system we have dies a natural death.  (At 4 hours per
day, 5-6 months per year, that may be a while) The mini-split is brand new.
It has efficiency that trumps any present window unit, but is not inverter
technology since I didn't get to choose.  (It was a nearly-free
"brother-in-law" deal, so it has its own type of cost effectiveness)


Posted by Mark F on September 25, 2009, 5:03 pm

On Wed, 23 Sep 2009 20:59:17 -0400, "vaughn"

The page:
  "Variable speed air compressor"
says that  
 "A Variable Speed Drive (VSD) Air Compressor is an air compressor
 that takes advantage of variable-speed drive technology."
 "The most common form of VSD technology in the Air Compressor
 Industry is a variable-frequency drive, which converts the incoming
 AC power to DC & then back to a quasi-sinusoidal AC power using an
 inverter switching circuit."

Are there any commercially available "inverter" systems that
can run directly from DC so as to eliminate the inefficiency
added using another inverter first to go from Solar or battery
DC to AC before feeding the compressor unit?

Posted by Bob F on September 27, 2009, 12:24 am

Mark F wrote:

It may be that the efficiencies of the AC motor make up for the losses in the
inverter. Reading about electric car conversions, the AC seems to win
significantly over DC for miles per charge.

Posted by Mark F on September 27, 2009, 1:49 pm

wrote in part:

The point is that the compressor unit typically changes AC to DC then
uses its built-in special purpose inverter to run the motor.  The home
power systems discussed in this group typically have DC available to
begin with, which is then fed to an inverter to get the AC; my
question asked if there were any commercially available units that
could be powered directly from DC, thereby eliminating the extra
inverter when powering the compressor unit.

Even with a 97.5% efficient main inverter, eliminating the extra
main inverter from the compressor power path saves is a 2.5%
and might lead to further system savings on the initial system cost
by allowing a smaller main inverter.

Posted by Bob F on September 28, 2009, 7:40 am

Mark F wrote:

My misunderstanding.

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