How best to run AC directly off solar?

 I plan on moving to a hot desert climate soon. Due to the amount of
sunny days, I got curious about solar PV options. After reading a bit, I
gathered that using batteries to store power on-site would not be
economical, and grid-tying likely would not be either.

The main use of household eletricity in that region is for air
conditioning. Disregarding the cost of the PV panels themselves, what's
the lowest-priced way to get home air-conditioning to run directly off
of the electricity produced by solar panels?

I am aware of the RV 12-volt units, and I'd guess to run them you'd need
at least one RV battery and a charge controller.... but then the
question is that I'd want the RV air conditioner to switch off
automatically whenever the battery dropped to a certain level. To they
have this function already built in? Or is there any easy way to do it?

Please note that only heat-pump air conditioning units are acceptable
for this purpose--swamp and ice coolers are not useful options.

Also we could assume that this would be in addition to the existing
house cooling system. The solar air conditioner would only ever be run
"directly" off PV power, and the rest of the time, the usual AC system
would run off grip power.
~

  DougC wrote:

Economics depends on your circumstances. :)

If you have grid power already then it's going to be cheaper than
installing solar PV. If price is your only consideration then don't
install solar PV at all and run the air conditioners off grid power.

If you don't have grid power already then solar PV can be cheaper
than getting the power company to install power lines. There is
also less noise, fumes and headaches compared to running your own
generator.


You can't. You need a battery to handle the surges and to store the
expensive solar PV electricity when the air-conditioning isn't running.


With the appropriate charge controller/load manager, it'll include a
low voltage shutoff that turns off everything when the battery gets low.

You might want to consider other, more affordable, options first.
Stuff like adding insulation, weather stripping, sun-blocking overhangs
or shutters outside the windows, geothermal heat exchangers or heat
pumps. Perhaps you could super-insulate just one room and only cool
that room during hot weather.

In some desert climates the temps drop at night. If this is the case
then a whole house fan could be used to cool the house.

Then there is the option of an ice-maker or heat pump that is directly
powered by the suns heat. These could be cheaper and more efficient
than using PV and electric heat pumps. I have heard of desiccant based
coolers that use water and a source of heat. Perhaps one of those
designs could be adapted for solar air conditioning. You won't find
these as off the shelf packages (at least, not cheaply) so you would
have to be willing to tinker some.

Anthony

 david.williams@bayman.org (David Williams) wrote in


I don't think that it would scale up that well.  
I did read an article once about a fellow who had bags full of water
on his flat roof. (WARNING: make sure that your roof is strong enough
for this before you proceed).  He would let them cool at night by
radiating to the sky.  Then in the morning, insulated panals would
cover the water.  The cooled water would keep the house cool by
conducting the cold through the roof.

 Williams) writes:

bt,dt,gtts. A similar technique is to wrap
a towel around the pot and place it all into
a slightly larger water filled tub.

The water gets sucked up the towel by capillary
action and gives you the same cooling.

--
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 DougC a écrit :

Except that in hot and dry climates, swamp coolers are a nice, generally =

economical way to cool... and I though heat pump air con used less
electricity than normal air con, wouldn't this be more interesting.