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Rest in Peace
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I've 520watts of solar & three 125AH batteries to store power. Goes threw a 30amp controller. Enough to power a 5cuft chest freezer & enough left over for some lighting & a small TV for monitoring weather.

The controller & inverter are in the conex storm shelter. Last summer I had two inverters fail from over temperature. Second one I had a 12VDC blowing directly on the controller but all the fan did was circulate 100+ air & the second controller failed.
So need some air conditioning to keep everything running. I would need atleast a 1KW solar system to be able to run the air conditioner off solar. Presently I'm running the air conditioner at 85F off commercial power.

Not a long term solution, but I think a small, 2,000watt generator would handle the air conditioner. The 2,000watt inverter will power the air conditioner.

Conex/storm shelter roof there is only enough space for another six panels or 600watts. Due to wiring & such, I would need to go ahead & do a separate system with the 600watts but according to my calculations it wouldn't be enough to power the air conditioner.

100F+ in the storm shelter would not be tolerable. Could use a small generator & just power the chaest freezer a few hours per day but that won't take care of the heat inside the storm shelter. So its a catch 22.
 

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I have heard about the "swamp coolers" used in the Southwest to cool houses. Water is pumped to the roof through a radiator and a fan directs the cooler air inside. At least that is how I understand it.

This might work for you, maybe your solar power might be able to run a small pump to move cold water to the roof?
 

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What you describe is a solar hot water heater. Wouldn't help at all. Infact, probably make it hotter inside the storm shelter.
 

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How many watts are lost to the controller? How are the heatsinks designed in it? By that I mean is there a way to provide liquid cooling to the heatsinks themselves? Most ICs can handle being at much higher than 100F temperatures. The problem is the 100F ambient air cannot remove heat fast enough for the ICs to maintain 100F junction temperature.

If you can research the IC P/Ns the data sheet will tell you the max junction temperature and the watts dissipated. Aavid, Wakefield, etc. are heatsink manufacturers and usually have charts in their datasheets to tell you the Linear feet per minute for a given temperature drop. At 100F ambient you could do it but I wouldn't doubt needing some velocity along the lines of a leaf blower!

As I mentioned in the first paragraph, some kind of liquid cooling would be able to remove the heat much faster and 100F water should be able to keep the chips alive. If you could rig up some geothermal unit to move the heat into the ground I think you would be quite pleased. If you can get deep enough, the earth is a great heatsink! This shouldn't require THAT much more wattage to run a small circulator pump.

If you are against plumbing, Peltier cooling MIGHT be useful. You will still need some healthy fans though.
 

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Discussion Starter #6
MorningStar controllers are suppose to handle the highest ambient temperatures but almost $200 for one.

And I can purchase a 2,500watt gas generator at Lowes for under $300. And can even elect to have it delivered to the house.
 

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I have heard about the "swamp coolers" used in the Southwest to cool houses. Water is pumped to the roof through a radiator and a fan directs the cooler air inside. At least that is how I understand it.
Your correct m1476251, they work great as long as the humidity is below 30% all the time. Here in Central New Mexico it gets down to 8-12% humidity every day, right now it's 88.3°F right now and feels like 84.0°F right now.


DI5
 

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Discussion Starter #8
And where I live in Florida 60-80% humidity is common in the summer.
 

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I think getting the controller that can handle the high temperatures is going to be the most reliable/cheapest solution. My only other suggestion would involve burying things underground or complete redesign of your shelter. Having to depend on mechanical cooling doesn't sound reliable either .
 

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Discussion Starter #10
Could do thermal & draw cool air out of the ground but having the pipe put in the ground wouldn't be cheap.

I do have a 5500watt generator that has a 30amp 240VAC plug for running my well pump. The thing is too heaving for me to be moving around much. Using gasoline, it would be easier to have a small generator out there at the storm shelter. Small generator just to run the air conditioner shouldn't use alot of fuel. Plus prefer keeping the inside of it from getting excessively hot to protect the food stores in there.
 

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In the gilded halls of Valhala
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get a large tank and submerge the units in silicon or mineral oil

hobbysts can do it with computers

if you can seal the container it should last for years

id go to a power company and buy an old single phase 50kva tank

seal the top bushimg holes and run your wires out the front bushimg holes.

a transformer repair facility will have old tanks they might sell.

weight wouldnt be a problem if you use a 25 kva that you buy stripped and use small diesel cans to move the oil.


have kitty litter for spills and make sure tank and oil is pcb free.
 

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Phonu, the problem is it removesheat from a specific place & assumes that hot air can be displaced. Room temperature 80 degrees & removing 100 degrees from the computer. If the inside of the conex is 100 degrees really can't remove 100 degrees from any point inside the conex. Would just be moving hot air doing little more then just a fan.
 

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HH a bit of shade goes a long way to help keep the temps down in a conex. Some camo netting in the short term with some fast growing trees for the long term. Of course the solar panels would have to stay in the sun.

We bought a couple of reefer conex (sans the reefer unit) put them under cover and stuck a 5 or 6000 btu window unit in each. The insulation is at least 10 inches thick. It doesn't take much the keep them cool. Even with the window units off it never gets over ambient. I don't remember how much those insulated conex cost but naturally it was more than the standard ones.

HH In previous post I believe you talked about insulating your conex, that couldn't hurt. However running any kind of traditional AC on solar is a tall order. Maybe a twist on geothermal would be feasible. The amperage required to run an AC makes running off of batteries mostly impractical. The best approach would be to have an array large enough to run the AC directly during the 5 peak solar hours (also the hottest) and still keep your batteries charged for incidental night time usage. During rainy and cloudy days not run the AC at all (which there would less of a need for cooling anyway).

During the peak part of the day my array produces 10kw we can run almost anything we need during that time. But even with 16 - 8D batteries (about 1200 Ah worth) I wouldn't dream of running an AC off my batteries at night.
 

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Thanks geek. That AC is marked at 9.2amps but I'm guessing that is only when the compressor is running.

By 10AM heat index here has been running 100 or more & by 7PM still around 95.

I only have space on the conex roof for another six 100watt panels & that will not be enough to run the AC. So I think a small gasoline generator is going to be the answer for now.

There is also the fact of possibly moving to Pensacola full time by the end of the year but keeping this place as a weekend retreat.
 

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more info

how about low tech,, small coleman cooler drilled for wires to run into& out of for inverter use and rotate those blue ice packs from freezer . cooler keeps outside temps out and blue ice keeps inside cooler temps down to moderate . if you are running small freezer or refridge keep extra blue packs and rotate them .
 

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Discussion Starter #17
Humidity from the condensation of the freezer packs would soon become an issue.
 

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Yes that would work. But would dread the rewiring of my solar system to allow wires to get to the cooler. Controller is 4-5ft up the wall & all the wiring is under osb sheeting.
 

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There will be a loss of efficiency going from metal to air to metal to air and the Peltier (Coleman cooler method) has to be up for the job. I don't know the specs for it but am pretty sure Peltier junctions are not known for efficiency. MAYBE if the transistors were mounted directly to the Peltier. MAYBE. Don't forget you are trying to move a hundred or so BTU. A cooler doesn't have to move nearly that much if the insulation is good.

If you are going to put heat into ambient air at 100F, you will need a very large heatsink with lots of surface area. More so if you expect to use convection to move the air.

Air has a very high specific heat but low mass. You have to move a lot of it to remove heat. A liquid (water) would have a decent specific heat and decent mass plus the ability to move (pump) to another location.

A SMALL Rule pump could move a LOT of heat if the liquid to air exchanger (car radiator with a small fan) for a given wattage used.

The physics are pretty simple. The question is cost.
 
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