Solar powered "root cellar"

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pengyou

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This is a hodge podge of topics, but one of the key aspects of this is the solar powered. I would like to be a very well insulated room on a 8'x14-16' flatbed trailer to serve as an above ground root cellar. Walls and floor will be r-30, ceiling r-50. It will very likely be pretty noise proof also. At first I was thinking of putting a chest freezer or two inside with a new thermostat set to 50 degrees. Option 2 is to not use chest freezers inside - unless it is actually to freeze something but to keep the entire room chilled to 50 degrees. Chilling would be done with 2 window a/c. One is probably enough for this size room, but the second one would serve as a backup. I have seen "thermostats" that make an a/c function as a freezer in a walk in unit. Basic, absolutely must requirement: to be able to power this thing from the sun. Do you think 72 sq. ft of solar panels can make this work? I would put batteries in for 2 days of operation, but really, when the sun doesn't shine, it is usually not so hot, so the a/c would not be in use. Any suggestions? A stupid idea? I will not be in a position to consider underground or in ground storage for the next 3 years, but I want to reach my food lts goals in about 3 years.
 
R 30 and r50 are allready really good insulation. Shading the area it’s parked in would help too. To answer your question on energy requirements you first need to find the cooling unit and see what it’s requirements are. There’s loads of refrigerated truck units out there. Try to get a look at one of those and then you design the solar setup for that.
 
I looked into refer units by accident some years ago - expensive because they are not run of the mill, and parts are even more expensive. Also many run on diesel or fossil fuels. I have seen some ads for a "thermostat" that can be used with a household air conditioner to make a walk in cooler. It is similar to the device that is used to make a chest freezer into a refrigerator. I need to learn a bit about heat transfer, etc...a little bit of physics.
 
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Nice! It is something to check out. I am guessing that he doesn't live off grid - he has R20 in his walls, but seems also, that his walk in fridge is contained within a building - maybe inside a garage?
 
This is a hodge podge of topics, but one of the key aspects of this is the solar powered. I would like to be a very well insulated room on a 8'x14-16' flatbed trailer to serve as an above ground root cellar. Walls and floor will be r-30, ceiling r-50. It will very likely be pretty noise proof also. At first I was thinking of putting a chest freezer or two inside with a new thermostat set to 50 degrees. Option 2 is to not use chest freezers inside - unless it is actually to freeze something but to keep the entire room chilled to 50 degrees. Chilling would be done with 2 window a/c. One is probably enough for this size room, but the second one would serve as a backup. I have seen "thermostats" that make an a/c function as a freezer in a walk in unit. Basic, absolutely must requirement: to be able to power this thing from the sun. Do you think 72 sq. ft of solar panels can make this work? I would put batteries in for 2 days of operation, but really, when the sun doesn't shine, it is usually not so hot, so the a/c would not be in use. Any suggestions? A stupid idea? I will not be in a position to consider underground or in ground storage for the next 3 years, but I want to reach my food lts goals in about 3 years.
...do u add a window AC to drop that ' start up' temp....hmmmm
 
Need a little advice from you root cellar people. In about 6-12 months my acreage should have everything ready for 2nd stage prepping to begin (root cellar, Garden, etc). Phase 1 is solar water, solar refrigeration, septic, fruit trees, large travel trailer, misc. fencing and catfish stocked ponds...

but I would like comments on what I plan for cool LT food storage. I plan on burying two Norwesco Bruiser Single Compartment septic tanks (11' x 4.5' x 5.5' high). Installing air vent hook pipes to promote air flow with insect screens and assist the flow with a little solar powered fan forcing hot air (high vent) out, thereby creating a vacuum effect in the tank bringing in cooler air. (As cool as it can get in Texas)

Do any of you with experience see any problems with this concept? I freely admit I am out of my depth on root cellars! or any other cooling methods that do not require heavy (A/C) techniques.

Any advice is appreciated
 
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Need a little advice from you root cellar people. In about 6-12 months my acreage should have everything ready for 2nd stage prepping to begin (root cellar, Garden, etc). Phase 1 is solar water, solar refrigeration, septic, fruit trees, large travel trailer, misc. fencing and catfish stocked ponds...

but I would like comments on what I plan for cool LT food storage. I plan on burying two Norwesco Bruiser Single Compartment septic tanks (11' x 4.5' x 5.5' high). Installing air vent hook pipes to promote air flow with insect screens and assist the flow with a little solar powered fan forcing hot air (high vent) out, thereby creating a vacuum effect in the tank bringing in cooler air. (As cool as it can get in Texas)

Do any of you with experience see any problems with this concept? I freely admit I am out of my depth on root cellars! or any other cooling methods that do not require heavy (A/C) techniques.

Any advice is appreciated

Through the years I’ve seen and used different root cellars. Never has there been a need for a fan, but never lived in Texas. How deep is your water table? If you can dig down where the bottom of your root cellar is 10 feet, you would have a very cool root cellar, even in Texas. How large is the opening on the septic tank? You need plenty of room to carry things in and out and an insulated door. You could pour a concrete bottom or my preference a gravel floor, and use cement blocks for the sides...well coated with water protection. Be sure to dig a trench around it with a hose to carry away water.

Be sure to put in 2 vents. One toward the bottom to bring in air, the other out the top to expel the ethylene gas. These should be 3 to 4 inch pipes.
 
Water table is no issue. I was planning on 10' depth. The tanks have 2 manways for maintenance each but food would have to be lowered down these manways as this would not be a walk in cooler but a buried tank, I am trying to avoid massive costs in trying to build an concrete cellar. yes two air vents per tank, one high one low. One of my unanswered questions is if the ambient temperature of the air is warmer than the temp at 10' depth would a vent system just warm up the food storage? I am wondering if the ventilation might work against me in the summer time. I told you I was less than ignorant :)
 
This is a hodge podge of topics, but one of the key aspects of this is the solar powered. I would like to be a very well insulated room on a 8'x14-16' flatbed trailer to serve as an above ground root cellar. Walls and floor will be r-30, ceiling r-50. It will very likely be pretty noise proof also. At first I was thinking of putting a chest freezer or two inside with a new thermostat set to 50 degrees. Option 2 is to not use chest freezers inside - unless it is actually to freeze something but to keep the entire room chilled to 50 degrees. Chilling would be done with 2 window a/c. One is probably enough for this size room, but the second one would serve as a backup. I have seen "thermostats" that make an a/c function as a freezer in a walk in unit. Basic, absolutely must requirement: to be able to power this thing from the sun. Do you think 72 sq. ft of solar panels can make this work? I would put batteries in for 2 days of operation, but really, when the sun doesn't shine, it is usually not so hot, so the a/c would not be in use. Any suggestions? A stupid idea? I will not be in a position to consider underground or in ground storage for the next 3 years, but I want to reach my food lts goals in about 3 years.


In researching solar applications I have found the following two links very helpful. Remember when sizing solar always take into consideration your start up (cranking) Amps on all motor driven items.

https://www.altestore.com/store/calculators/off_grid_calculator/
https://rimstar.org/renewnrg/sizing_select_batteries_for_off_grid_solar_system.htm
 
I wouldn't be investing that $$$ into some temporary half-azz cooler unit >>> if you have space on your property for that unit - you can construct a building that has a full-time usage package besides being a cooler ....
 
Water table is no issue. I was planning on 10' depth. The tanks have 2 manways for maintenance each but food would have to be lowered down these manways as this would not be a walk in cooler but a buried tank, I am trying to avoid massive costs in trying to build an concrete cellar. yes two air vents per tank, one high one low. One of my unanswered questions is if the ambient temperature of the air is warmer than the temp at 10' depth would a vent system just warm up the food storage? I am wondering if the ventilation might work against me in the summer time. I told you I was less than ignorant :)

You are far from ignorant! With enough earth mounded over the majority of your roots cellar, there would be no problem. Not being able to walk into a root cellar is a problem. Did I get that wrong? Do you have a hillside you can put it in to?
 
not enough of a hill, more just s shallow slope grade(1':30'+/-)... good thing about advance planning is you get to "measure twice, cut once"... trying to hold this down to under $4K..just bouncing the ideas around now
 
David,

I'm also in central Texas. Our ground temps are in the mid-60's year round. But you will want to exchange air to avoid mold/moisture. You also need to make sure these will not fill with water. Some questions.

1) I assume you are not in hill country rock? So... east of I-35 by 'enough'?
2) Why 10 ft down? trying to avoid ___? (what?)
3) How much sq ft or cubic feet of space do you need?
4) What are you storing (generally speaking)? How often will you need access?
5) Would you see staying down there for hours/days/weeks?

Some thoughts. Not fond of septic tanks. Heavy duty, yes. But keeping water out is not their strong point. And access sucks bigtime. For ventilation, run a PVC pipe from the surface about 4 ft down and across maybe 100 ft. Have a fan that blows air downward into it (solar?). The 100 ft horizontal run will drop the air temperature to the soil's 65F temperature. More importantly it will reduce mold/moisture issues. Second pipe coming up for exhaust (or combine with your human-access point). Sloped walkway or staircase down will be worth it's weight in gold if you have to come/go often. Put this under a building or something for concealment. Have a way for moisture to get pumped out (if you know about sump pumps for houses with basements). If you need more room, consider burying a shipping container. But you will need to do cement poured walls around it (steel reinforced) to handle the ground pressure. Just my initial thoughts.
 
Water table is no issue. I was planning on 10' depth. The tanks have 2 manways for maintenance each but food would have to be lowered down these manways as this would not be a walk in cooler but a buried tank, I am trying to avoid massive costs in trying to build an concrete cellar. yes two air vents per tank, one high one low. One of my unanswered questions is if the ambient temperature of the air is warmer than the temp at 10' depth would a vent system just warm up the food storage? I am wondering if the ventilation might work against me in the summer time. I told you I was less than ignorant :)
The air flow will loose some of the cooler air but without the flow you will have too much moisture buildup and as GP said ethylene has too.
 
In researching solar applications I have found the following two links very helpful. Remember when sizing solar always take into consideration your start up (cranking) Amps on all motor driven items.

https://www.altestore.com/store/calculators/off_grid_calculator/
https://rimstar.org/renewnrg/sizing_select_batteries_for_off_grid_solar_system.htm
A small fan with a solar panel would be enough to move air. You don’t need a big setup. I just use natural airflow in mine With a low and high ven.
 

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