First Off-Grid Solar Freezer (for Dummies)

Login or register to post comments Last Post 110661 reads   41 posts
Viewing 10 posts - 31 through 40 (of 41 total)
  • Tue, Aug 12, 2014 - 04:53am

    #31
    TechGuy

    TechGuy

    Status Bronze Member (Offline)

    Joined: Oct 13 2008

    Posts: 308

    count placeholder0

    Putting them at ground level

Putting them at ground level instead of the roof is a much better in my opinion. In the event that you need to take them inside, ie a hail storm, hurracane, etc. its far easier to move them. I would sugguest some sort or easy remove fastners to the frame so you can remove them quickly and with out aggravation. That said you need to mount them to a reboust frame so that can't blow away in a windstorm, as well as two legged predictors that may spot your panels from a distance.

FWIW: I would consider mounting them on a fulcrum frame (ie like a teeter totter) so that you can set up a sun tracker that would track the sun as it rises and sets in the day so you can maximize output for more of the day. The pole could be actulated using a motor(s) attached to a screw drive(s). Its probably not possible to get a full 180 degree travel, but even a modest 60 degress of travel would do a lot. That said you probably need some basic metal working skills and welding to make it right.

Another consideration is thermal panels for Domestic hot water as perhaps using extra hot water to extend temperatures in greenhouses.

  • Tue, Aug 12, 2014 - 05:25am

    #32
    TechGuy

    TechGuy

    Status Bronze Member (Offline)

    Joined: Oct 13 2008

    Posts: 308

    count placeholder0

    “You mentioned how does one

"You mentioned how does one use supercaps to help a compressor motor get over the large startup current pulse: Such electric motors already have a "starting capacitor" attached to their surface to help them start."

Starting Caps are using in AC motors improve starting torque. However these have tiny capacitors and are not useful when the input voltage is low or the power source is unable to supply sufficient current. An AC motor cap will have ~70uf to ~200uf (or 7x 10^ -6 Farads) The are intended to increase the draw of power from the power source because motors have large inductances can have high impedances preventing sufficient current to start up the motor.A SuperCap will work more like a battery and has a charge storage measured in Farads, or about a half million times more than an AC motor cap. 

I was presuming the person asking about avoiding batteries was because batteries don't last very long when they have a large number of discharge cycles. A typical lead-acid battery probably will last 300 to 700 cycles, depending on the depth of discharge. Often oversized battery banks are used to limit the depth of discharge so they can last a longer number of cycles but this gets expensive and large banks costs lots of $$$. A SuperCap has an extremely larger number of cycles (100K to 1M). so would last essentially forever, but they don't have any where near the capacity of batteries. A 10F SuperCap bank would probably only be able to run the motor for a few seconds where as a battery can run a motor for 30 minutes or longer. The idea is to use the Supercaps to supply sufficient startup current to get the motor running when the solar cells can't supply enough power for startup. (ie low angle, shadows, partial overcast, etc).

Alternativatly Super caps can also be used with Battery banks to extend the life of the batteries. The Super-Cap will reduce the stresses on the batteries by providing the power for sudden surges when a device is turned on (ie compressor motor). Super caps have a much lower internal resistance the bulk of the inital current will be drawn down from the supercaps before drawing from the batteries. 

 

  • Tue, Aug 12, 2014 - 05:37am

    #33
    TechGuy

    TechGuy

    Status Bronze Member (Offline)

    Joined: Oct 13 2008

    Posts: 308

    count placeholder0

    DIY Refigeration

"I have built the freezer into the house and am not using the built in condenser. This saves floor space, allows for an external condenser to heat water and dissipate waste heat outside the house and triple the insulation around the freezer. To minimize cost, voltage drop and copper cable I have used a ring circuit. "

Yes, this is a better design than a off-the-shelf commerical unit. Replacing the gas with propane you can get much lower tempertures too (-40C or -40F for propane). This would be usefully for long cycles when the system can't be run at night. Ideally you could set it for a very low temperature so that you have sufficient low temperature carry through a long period. Another idea is to use set of  tanks that could store excess compressed refrigerant that is bleed to provide cooling when the compress isn't running or can't be run. it doesn't take much power to toggle a solenoid value compared to the compressor. Although you would need two tanks, One for the compressed refrigerant and another as an expansion take to hold the expanded refrigerant.

FYI: a source of DIY refrigeration parts can be found at http://www.rparts.com/

 

  • Sat, Nov 28, 2015 - 11:39pm

    #34
    sdorey1222

    sdorey1222

    Status Member (Offline)

    Joined: Nov 28 2015

    Posts: 1

    count placeholder0

    Solar Freezer

I read all the instructions for the freezer, what type, what to buy, etc. I have an upright freezer right now I was hoping to figure out how to hook up to solar. It is a 14 CF Sears. I wanted to try and use it for a very selfish reason. I suffer from very bad migraines (daily) and require ice bags and gel packs nightly. At times all day. Is there a way to use my Sears freezer or do I need to purchase a new smaller one?

  • Wed, Dec 30, 2015 - 10:01am

    #35

    KhaledElsheref

    Status Member (Offline)

    Joined: Dec 30 2015

    Posts: 1

    count placeholder0

    Off the Grid Power

Off the Grid Power Systems

When you talk about off the grid power systems, alternative energy and living in off the grid houses, most immediately think that they will have to abandon most of their up to date gadgets in order to survive in such a way. Many more believe that off grid solar power is only used by green hippies, whose modest ways coincide with fewer technologies such as TVs, ACs, etc.

Realistically though, living off the grid can be achieved by everyone who wants to. Admittedly, you may have to spend more money if you are powering three chest freezers as well as lots of other high-energy appliances, but then you would require a larger system. http://www.altairsolar.com/home The increased demand for renewable energy systems has speeded up the development of more efficient and simple to use components to make off the grid power systems a reasonable option for anyone wants to be mindful of their energy usage.

Using renewable energy sources to produce power is a fairly simple process. You need a source of power – sun, wind or water – from which you will collect a low voltage DC (direct current) that is then converted, using an inverter, to AC (Alternating Current) which can be used in the home. Extra current the system generates is stored in banks of batteries from where it is retrieved when there is a high demand or times when the direct power supply is cut off. Off grid power living using renewable power resources can be almost totally automated too.

Except for the maintenance of your batteries, there is almost no extra attention required, except to monitor your energy usage to ensure that you do not exceed your supply with your demand. The main thing that you must do is making certain the size of the system is sufficient to meet your needs. Off the grid power systems are an exhilarating way of life. The feeling of energy freedom is like no other and you can be proud of your attempt to combat global warming and most importantly, you will never have to worry about an energy outage again.

It is important to conduct your research and find out which renewable energy sources is going to work the best for you where you live, but it is certainly worth knowing how to manage off the grid and experience the freedom living off the grid can give.

  • Tue, Mar 29, 2016 - 11:09am

    #36
    Voodoosunday

    Voodoosunday

    Status Member (Offline)

    Joined: Mar 29 2016

    Posts: 1

    count placeholder0

    Insulation

Correct.

Technically, the only reason why a chest freezer requires ANY energy input at all is to make up for the losses across  the insulation boundary ( excluding the  addition of warmer contents, of course)

An effective, although enormously costly solution would be to construct the freezer cheat as a rather large Dewar flask, with double skinned walls between which there exists a hard vacuum.

 

The same thing applies to geysers …. The only reason they consume any standby power at all is because of insulation losses, which would be amenable to a similar solution.

  • Mon, Aug 01, 2016 - 06:45pm

    #37
    Karadean

    Karadean

    Status Member (Offline)

    Joined: Aug 01 2016

    Posts: 1

    count placeholder0

    Edgestar freezer won’t work on 12 volt, only AC

I wonder if the transformer can be bypassed since the condenser is 12 volt DC. Seems like it would be possible. more efficient as well. I don't need to run it on 110AC. It is on solar powered batteries and right now we are running it with an inverter between the batteries and the freezer. I have contacted Edgestar and they were no help.

  • Mon, Aug 01, 2016 - 07:21pm

    #38

    Michael_Rudmin

    Status Gold Member (Offline)

    Joined: Jun 25 2014

    Posts: 881

    count placeholder0

    If you want DC cooling,

I would try some of the Peltier-device coolers.  The Peltier device, if I understand correctly, is the solid-state equivalent of a heat engine, but it runs on DC electric.  So you could get a little 12-V or 24-V power supply, and run it off that.

Another thing I might try:  Dewalt is moving their battery-powered tools to 20V/60V interchangeable.  Some of the tools they have include an 1800 W AC power supply that runs off their battery packs. 

I could see doing a bunch of those…  over here, you charge the batteries.  Over there, you use them for anything from DC60 to DC20 to AC120.   

  – Mike Rudmin

  • Sun, Oct 01, 2017 - 05:30pm

    #39
    markzoes markzoes

    markzoes markzoes

    Status Member (Offline)

    Joined: Aug 27 2017

    Posts: 1

    count placeholder0

    Update

Informative thread.

  • Thu, Aug 13, 2020 - 05:24am

    #40
    awconverse

    awconverse

    Status Member (Offline)

    Joined: Aug 13 2020

    Posts: 2

    count placeholder0

    First Off-Grid Solar Freezer (for Dummies)

I have a question about the calculations for running the freezer. Since these freezers are built for efficiency, why is the value of about 3 amps per hour per day used?

If the freezer is in a cool location (inside the house, maybe in a cellar or cool area) wouldn’t the unit cycle far fewer times a day given the efficiency of the insulation and the likely hood of not opening the freezer more than twice a week? If so, then wouldn’t the calculations be about half the amps needed over a 4 day period?

Viewing 10 posts - 31 through 40 (of 41 total)

Login or Register to post comments