If you want a cheaper electric bill each month the answer is simple, abstain.
But since we all know that will never happen...
On your AC units there will be a tag or sticker showing the voltage, and the amperage that is required for the machine to function properly. It may only show a maximum or minimum breaker or fuse size. Go with the maximum for these calculations. Once you find them quickly multiply them. Now you know the wattage they(you) need. Now you will need to know the number of hours you will need the machine to operate. Once you have that, quickly multiply the number of hours times the wattage. Ok its about time for an example here. Lets say one of your AC units requires a 30 amp circuit at 240 vac.. That would be 7200 watts, now pick a PV module, any module... go ahead just pick any one... good choice,
A Kyocera KC175GT with a price tag of $885.00 U.S.
Of course the more one purchases the less they cost each which is a good thing because you will need at the very least 42 of them at $37,000.00 U.S. in order to stay cool for about 6 hours or so. Maybe ten if the home is well insulated and the doors do not get opened much. This would also depend on the number of hours of equivilent full rated charge you could get from a PV module in your region.
I got those number by taking the 7200 watts and dividing it by 175 and rounding up. If you need the AC at night then just double the PV array size and add a bank of batteries. Lets see here that would be 7200 watts for 10 hours? or 72,000 watthours (72kWh) divided by a nominal voltage dc of 48 which is 1500 amphours at 48 vdc. Of course the batteries would be dead every morning so we should make the bank a little bigger. Its always best to shallow cycle deep cycle batteries because they live longer and will not have to be replaced as often. So shall we say 5 times for a battery bank of 7500 amp hours at 48 volts.
Now pick a battery... go ahead... Ahh! the Surrette 2KS-33PS, 2 Volt single cell, 1766 AH @ 20 hour rate. $590.00 U.S. each.
It will take 24 of them in series to make a 48 volt bank at 1766 amp hours and at least 4 of those banks to make 7064 amp hours. close enough. For a cost of $56640.00 U.S.
Lets add the PV array $70,000.00 and now we have $127,000.00 Then there is the inverters... huhh?... hello!... Where did he go?...We didnt even get to talk about how much the power company would pay him for his electricity! If you see him tell him to check out
www.dsireusa.org Thanks.
Once upon time PV was looking good. The quality was going up and the prices down. But then all of a sudden new manufactures are poping up like weeds all over the world and now there is this "shortage" in the raw material stock (silicon) for making PV cells and the quality has started on a decline while the prices are going up. Progress?