Solar powered AC air conditioning, a bummer or a challenge?

[K7ABE]

Solar-PV will be one of the first casualties from any sort of EMP event. Long wire runs and large inductive loops.



In general "building your own" solar panels and batteries isn't going to do much, will take forever, will cost you far more than buying commercial and won't teach you much about solar. It would be like trying to build your own car, and starting out by planting a rubber tree for the tires. Sure, you will learn a lot about rubber trees, but not much about modern cars.

If you really want to learn about solar there are plenty of components out there you can bolt together and play with. You can quite easily build a small system to (for example) run some yard lights at night. You'll learn about battery charging, hours of effective sun, the role panel azimuth and elevation play, battery temperature compensation etc. And if you burn through a pair of GC2's in your first month you're only out about $300.

Solar panels are semiconductors much like a diode, transistor, or IC chip. They start with a thin slice of quartz that is masked, then an etchant is used and they are built up in the same way any semiconductor is. They are very sensitive to EMP, even RF radiation. Solar panels stored inside metal buildings may work after a large EMP.
Abe

[K7ABE]

Still being funny - you have no idea what you are posting - pure baloney!

This is not a duct tape site where one is encouraged to cobble stuff together.

The original poster stated he does not have a few thousand dollars to work with. A cheap high frequency inverter will not handle the inrush of an air conditioner. I have a 2500 5000 that went into default and has not worked since I try to it. The low-frequency heart 2k does handle the inrush of the air conditioner. There is a heart 2.5k on ebay for about $600. A new low frequency inverter that will handle his air conditioner will cost two or three thousand dollars. I hope this is not a site where you discourage people or run them off if they cannot buy your new products.
Abe

[K7ABE]

200 AH is meaningless without a voltage. So I can only assume you are talking about 6 volt 200 AH golf cart batteries wired in series to make 12 volts. 12 volts x 200 AH = 2400 watt hours. For an off-grid battery system you size the battery to give you 5 days run time. In reality this only gives you 2.5 days as you never want to discharge the batteries more than 50%. Put another way you only discharge your batteries 20% each day.

Battery cycle life and Depth of Discharge is directly related. The deeper you discharge them, the fewer cycles you will get out of them. Here is a chart to display:



Discharge 20% each day and you get about 5 years, 50%just over a year, 100% just a couple of months. In your case using a 12 volt 200 AH is 2400 watt hours and you want to drain 600 watts x 7 hours = 4200 watt hours. Not going to work.

So your air conditioner uses 600 watts and you want to run it 7 hours per day. 600 watts x 7 hours = 4200 watt hours. That means you need a minimum of 4200 watt hours x 5 days = 21,000 watt hours or 21 Kwh. To find the battery AH capacity is easy Amp Hours = Watt Hours / Battery Voltage. So you get:

1750 AH @ 12 volts
875 AH @ 24 volts
438 AH @ 48 volts

To determine cost a good 5 year battery will cost you $220/Kwh and weighs roughly 55 pounds per Kwh. So for a 21 Kwh battery will cost around 21 x $220 = $4620 and weigh in around 21 x 55 pounds = 1155 pounds.

Compare the life cycle charge between Interstate golf cart batteries, Trojan batteries, And rolls-royce batteries. The ratings look close at first but the golf cart batteries are rated at 20% discharge, The Trojans are rated at 50 percent discharge, And the rolls-royce at 80% discharge. If you treat a better batteries like the cheap batteries they will last 15 or 20 years. If you treat the cheap batteries like the better batteries they only last 1 or 2 years. The manufacturers numbers are deceptive at first look.
Abe

[russ]

Try crunching those numbers with a $5 or $10 AGM battery. Cell towers keep their battery topped off and cycled them out every one or two years. The battery still may last five to eight years after that. This will drop your battery cost down to the penny or two per kilowatt.
Abe

Still being funny - you have no idea what you are posting - pure baloney!

This is not a duct tape site where one is encouraged to cobble stuff together.

[K7ABE]

I had an idea for my camper trailer build that May or may not work for it.
I saw a 12v air conditioner add on kit made for a truck that mounts under the dash. 7000 btu (I think).
Saws it on eBay. It would have to hang from a wall cabinet or something. I haven't found any info on weather someone has tried something like that in their home.
That would be cool if I could do that, but there would be many hurdles to overcome.

A refrigerator and freezer are available with 12 volt compressor that will run off of a solar panel with no batteries. The compressors are available by there self. Using them for AC units is an idea I have on the back burner.
Abe

[K7ABE]

Factual figures from one of my products.
$300 AGM Battery...
216WH daily use...
X 365 = 78840WH annually...
X 5years = 394200WH
/1000 = 394.2KWH of service life
$300 / 394.2 = 76¢ per KWH

^^^ and that doesn't include the cost of the panels, charge controllers, wiring and hardware.

Also, consider the battery may last only 3 years,,, raising the ¢ per kwh figure.

Try crunching those numbers with a $5 or $10 AGM battery. Cell towers keep their battery topped off and cycled them out every one or two years. The battery still may last five to eight years after that. This will drop your battery cost down to the penny or two per kilowatt.
Abe

[billvon]

I'm not one of those geeky prepers who keeps a bug out vehicle, and a cabin in the woods with 1000 pounds of canned food. But if the US dollar ever collapsed, or I there is a super virus outbreak, or Iran takes us back to the Stone Age when they develop an EMP device, then I'd rather not be one of those who died immediately because I didn't have a plan B.

Solar-PV will be one of the first casualties from any sort of EMP event. Long wire runs and large inductive loops.

If a low cost solution IS viable, then maybe I'll start looking into ways to make it more viable.
EG building my own solar panels, and batteries, improving circuit designs and building the components myself, etc. I am trying to start small but I really have a grand vision if it works out.

In general "building your own" solar panels and batteries isn't going to do much, will take forever, will cost you far more than buying commercial and won't teach you much about solar. It would be like trying to build your own car, and starting out by planting a rubber tree for the tires. Sure, you will learn a lot about rubber trees, but not much about modern cars.

If you really want to learn about solar there are plenty of components out there you can bolt together and play with. You can quite easily build a small system to (for example) run some yard lights at night. You'll learn about battery charging, hours of effective sun, the role panel azimuth and elevation play, battery temperature compensation etc. And if you burn through a pair of GC2's in your first month you're only out about $300.

[russ]

Whatcha mean Russ? There are many prepers out there. You should know better than most because you lived through the Cuban missile crisis and whatnot.

Yep, I remember that - all a bunch of hokum - tempest in a tea cup.

[PhillyTitan]

Preppers? I have been hearing that BS as long as I can remember - I am 69 so that goes back a ways.

Whatcha mean Russ? There are many prepers out there. You should know better than most because you lived through the Cuban missile crisis and whatnot.

[PhillyTitan]

I had an idea for my camper trailer build that May or may not work for it.
I saw a 12v air conditioner add on kit made for a truck that mounts under the dash. 7000 btu (I think).
Saws it on eBay. It would have to hang from a wall cabinet or something. I haven't found any info on weather someone has tried something like that in their home.
That would be cool if I could do that, but there would be many hurdles to overcome.

[russ]

Preppers? I have been hearing that BS as long as I can remember - I am 69 so that goes back a ways.

[PhillyTitan]

I build many 12 volt swamp coolers to stay cool here in california, humidity rarely gets over 50 so they work great. I always look at youtube among other areas to learn ways to improve on the design of the swamp coolers I make.
There was a design I saw on youtube of someone using a heater core radiator with hoses going into a ice chest filled with cold water, he had a fan blowing on the radiator. the pump circulated the cold water through the radiator. He had a thermometer showing a drop in temperature. This is a very primitive A/C. The only downfall I saw was feeding ice to the ice chest to keep it cold. In my mind I had and idea, what if you just filled a 12 volt fridge full of water and ran hoses from there instead of an ice chest. You would always have cold water without needing ice.
12 volt fridge only uses 4 to 5 amps when its running. Water pump uses 1 amp, you can use a endless breeze fantastic fan that produces 900 cfm of airflow at less that 3 amps as the air source. I know something like that would easily run off my 240 watt solar panel.
Your idea to get AC on solar/batteries is possible but you need to think outside the box and maybe build something on your own.
If I really needed AC, I would definitely build something like the above. For me it would be a challenge that I could not refuse, I would not give up too easily.
But also dont overlook swamp coolers, growing up in texas with high humidity and temperatures in the 100's, and giant mosquitos we never had an AC, all we had was a giant swamp cooler in the living room and that kept the whole house cool. You can build your own 12 volt one cheaply and they are very solar friendly.

I wish swamp coolers would do the trick, but they can't even cool my 11x4' laundry room (converted storage room). That primitive AC sounds like a neat idea though.

[PhillyTitan]

For your standby/emergency system you want a generator - not solar

That's not really what I'm going for either (oil dependence)

[jony101]

I build many 12 volt swamp coolers to stay cool here in california, humidity rarely gets over 50 so they work great. I always look at youtube among other areas to learn ways to improve on the design of the swamp coolers I make.
There was a design I saw on youtube of someone using a heater core radiator with hoses going into a ice chest filled with cold water, he had a fan blowing on the radiator. the pump circulated the cold water through the radiator. He had a thermometer showing a drop in temperature. This is a very primitive A/C. The only downfall I saw was feeding ice to the ice chest to keep it cold. In my mind I had and idea, what if you just filled a 12 volt fridge full of water and ran hoses from there instead of an ice chest. You would always have cold water without needing ice.
12 volt fridge only uses 4 to 5 amps when its running. Water pump uses 1 amp, you can use a endless breeze fantastic fan that produces 900 cfm of airflow at less that 3 amps as the air source. I know something like that would easily run off my 240 watt solar panel.
Your idea to get AC on solar/batteries is possible but you need to think outside the box and maybe build something on your own.
If I really needed AC, I would definitely build something like the above. For me it would be a challenge that I could not refuse, I would not give up too easily.
But also dont overlook swamp coolers, growing up in texas with high humidity and temperatures in the 100's, and giant mosquitos we never had an AC, all we had was a giant swamp cooler in the living room and that kept the whole house cool. You can build your own 12 volt one cheaply and they are very solar friendly.

[russ]

For your standby/emergency system you want a generator - not solar