peggyb, it all comes down to power. A solar panel that's 52" x 21" good for 50 watts costs about $300.

http://www.solarpanelstore.com/solar-power.large-solar-panels.solarworld_sw.sw_50.info.1.html

where as a very small window a/c good for one room (5500 BTu/hr) will require 490 watts or so, for example:

http://www.sears.com/shc/s/p_10153_12605_04275051000P

So if you buy ten of these panels for $3000, you can run your ac. But you'll need an inverter, because they're 12 volt. Also, you'll probably want to go to batteries first, to smooth-out the power and AC a little after dark.

It's just not cost effective. My whole elec bill won't equal that is three summers, and that's just for the one-room ac.

Maybe you could power a laptop from the 50 watt $300 panel. Then at least you'd feel 'green.' You can buy any of these from the 'solarpanelstore' website, or many others. good luck.

Running a refrigerated air conditioner pulls about 20 amps at 220vac or 4,400 watts. So a solar cell system would cost quite a chunk of change. However, if you live in a region where you can use evaporative cooling (swamp cooler), those units only use 110vac at 5 amps or 550 watts; only 25% of the power.

Solar cells are available at 200 watts per panel for about $800 each, so it would take about 3 panels, a 12v car battery, a 1/2 farad capacitor (increases the life of the battery), and a 12v/120v inverter. Be sure the inverter has a low input voltage shutdown circuit so that electronic parts won't smoke when clouds get in the way or dusk shuts down your system.

You'll also need a method of keeping the cells pointed towards the Sun. Lots of circuits and mechnisms are out there on the internet for downloading.

As a result you could run your house air conditioning during daylight hours on solar energy.

$125 12v/120v Inverter

Assorted Solar Cells for sale

Also, when this subject comes up, many people speak negatively of the engineers that comment with facts and rain on the parade.

http://www.whynot.net/ideas/4093

http://www.whynot.net/ideas/347

I want to say that I (and probably the other engineers) support the future of solar energy, but as a pragmatist, I don't count on a "Moore's Law" or some incredible breakthrough, especially in photo-voltaic cells.

I do think that using a power-plant mentality, the future will find ways to use waves, geothermal, the jet-stream or any other number of natural enegy sources to capture 'solar' energy.

I just think that since solar cells don't even replace their energy fabrication costs at this point, we should wait. The market is a great decision maker.

And firewood is a capture of solar energy too. I use it now for supplemental heating. Self replicating and self-energy storing.

You are thinking in the wron box, or at least the wrong side of it.

For PhotoVoltaic panels, you don't necessarily use one to directly power a particular appliance (unless the appliance would work well with solar derived electricity).

The popular approach (if you are on grid) is to sell the electricity generated by the panels to the utility in the day, and your loads would take what they need. You (or they) essentially pay the difference in what you produce and what you draw.

Outside of the box (or if you are off grid), you design your house not to heat up, or naturally cool with no need for an A/C anyways.

If one is considering solar to be green as a whole, yes, one would have to consider the pollution produced/energy spent in manufacturing, transportation, and installation of the units and companion equipment. For purely economic, self sustainability, or "localized" green reasons, you can probably ignore the overall footprint the units have already created.

As for firewood, I don't think it sustains itself too much, plus there is fuel spent in collecting and processing it, not to mention the labor involved.FWIW, we burn wood here primarily, obtained as cast off pieces from hardwood, or already dead trees.