Re: [hreg] Appliance Conversion
- Yesterday, Katherine Hannah wrote:
> Is it possible to convert an AC appliance to DC?Technically possible, sure. But probably not worth it for most things.
> Just curious.
> Kathy Hannah
Pretty much any motors are going to be AC. You'd have to replace them to
Heating elements don't care. They'll run on DC as easily as AC. But that
doesn't mean the control electrics/electronics will.
Electronics run on DC. But the problem there is supplying the right voltage.
A lot of things run on multiple voltages, and need power supplies to convert
from 120V AC to the several voltages they use internally. For example, a
computer runs on +12V, +5V, and -12V (or is it -5V?). (See PS for more.)
Another issue is that DC is typically 12-48V (say, from a bank of batteries
being charged by a PV system). And the lower the voltage (DC or AC), the
larger the wires have to be to carry the current.
You're better off buying high-efficiency appliances, and trying to reduce
your usage (turn up the thermostat--or turn it down, now that it's cold). If
this isn't about efficiency, and you just need to run an appliance off of
DC, you can get 12VDC to 120VAC inverters for cheap. Or you can go to an RV
store, and find some small appliances (say, blenders and small fans) that
are designed to run off the DC system in an RV.
PS There was an interesting story recently about Google trying to convince
computer manufacturers to build motherboards that only need one voltage in.
It would save them on power, since they'd be able to use large AC to DC
recifiers outside of their data center (which they wouldn't have to cool),
and it'd be more efficient.
I went to a seminar Wed about power and cooling in data centers (a data
center being the central room where companies keep all their computers). A
guy who does data center infrastructure for HP was there, and shared some
interesting numbers. They have about 600,000 s.f. of data center space
total. One 200,000 s.f. facility they have costs them almost $1 million a
year in electricity. And cooling is a big part of that. For a 20,000 s.f.
facility, if they try to lower the temperature in the room by 1 degree, it
costs them $200 an hour!
Most large data centers like that have 20-ton A/Cs (or air handlers,
technically, since they're usually chilled-water units) scattered around
all over the place. Our data center (I work for the Human Genome
Sequencing Center) is only 800 s.f., but we've got two 20-ton units (and
we're running out of cooling capacity). For comparison, your home A/C is
probably a 4-6 ton unit.
- I didn't look at the cost of such units charged by its manufacturer, but based upon equivalent system, it was an estimated cost. Moreover, although such a system occupies less space, yet it may not be suitable for all people. The first thing oone has to to do is the "Citing Analysis," (location, availability of space for placing Solar PV modules, and affordability).Bashir A. Syed----- Original Message -----From: Paul ArcherTo: Michael K EwertSent: Saturday, December 09, 2006 7:35 AMSubject: Re: [hreg] SunBall evaluation from the photograph and dimensions provided on the Website.
Yesterday, Bashir Syed wrote:
> I looked at the photograph of this device called Sun Ball, with dimensions
> of 0.95-m X 0.95-m X 0.24-m, and claiming to provide 600 kWh per year,
> with dual axis tracking mechanism. Considering a peak Sunlight-hours of 6
> hours per day in Australia, it amounts to an equivalent of Peak 273-Watts
> of power. This translates to a peak efficiency of approximately 27 %, and
> with all modification to increase this efficiency Plastic Fresnel Lenses,
> internal reflectors, and dual-axis tracking it would cost about 5 to 6
> times the price of 100-Watt PV Module.
Out of curiosity, are you guessing that it would cost 5-6 times the price of
a 100w PV module, based on what you think it would cost to make--or are you
looking at what the company is saying they cost?
- Thank you. That was right on target. My son had told me that he knew of people living off the grid in mobile homes who were doing AC to DC conversions (inside every AC appliance lives a DC appliance just waiting to get out). I thought it was more complicated than that.Kathy Hannah