# Solar power for 1 fridge, and 1 freezer



## thestartupman (Jul 25, 2010)

What would be the best set up to provide solar power to 1 fridge, and 1 freezer? I don't want to have to use propane. I am open to any other suggestions though. Lets say you have no other source of power for the place they will be located. I am okay with building a special building to house them in with special insulation if it would help. It would be great if it could be designed to be used without batteries. Maybe if the building was insulated good enough, it could run during the day, and be off at night? I would prefer that they be normal size appliances. Any thoughts or ideas would be greatly appreciated. Hopefully with enough people brainstorming, we can come up with a great solution. Thanks


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## Dixie Bee Acres (Jul 22, 2013)

I'm sorry, but I don't think you would ne able to run them on solar without batteries.
More than over night, you also have to worry about cloudy, rainy days.


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## thestartupman (Jul 25, 2010)

It doesn't have to be without batteries, but it would be great if it could be. I would rather use a generator on the cloudy days. We don't seem tohave many cloudy days anyway.


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## jwal10 (Jun 5, 2010)

Regular sized 120 volt freezers and refrigerators take a fair size solar power system. Needs to be enough for when both happen to start at the same time. It would need batteries. Batteries will seem cheap with the price of fuel to run a generator, much. Food in a freezer that does not start, as needed, will not keep well. IMHO....James


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## Gray Wolf (Jan 25, 2013)

You'll need batteries and a generator.

I think you need to think more about this super-insulated building. Just putting ref &freezer inside and closing the door won't work without some more tricks.

How do you avoid having the waste heat from the compressors from making the building warmer - which makes the compressors run longer which makes more heat which ........

How do you prevent everything in the ref from freezing in winter?

Do you leave the door to the building open all summer?

Every time you want in the ref or freezer you open the building door and dump all the warm / cold you have stored. How many times per day/week to you need inside the building?

While superinsulating the units themselves is probably better than the superinsulated building, I think you should be looking deeper into what freezer and ref you will actually use. Most of them have the radiator(s) that dump compressor heat located such that you will kill its ability to dump heat if you just stick insulation everywhere. Insulation needs to NOT cover the radiator(s).


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## thestartupman (Jul 25, 2010)

Gray wolf, I think you took my post wrong. I am looking for ideas of how to do it. My thoughts were just random ramblings to get feed back coming on the best way to have a fridge and freezer of some kind that could run off solar power, or any other type of power system besides the grid. I know that there is a battle between the cooling of a fridge, or freezer, and the heat they put off. Trust me I am open to all ideas of being able to do this without the grid. If I could do it with a bike, I would consider it. All I know is I have no flowing water for hydro, the wind is plentiful at times, but can shut off for weeks at a time. I have clear blue skies most of the time. I would even consider a fridge/ freezer building if I could find a way to run it without the grid. Any ideas on how to do it would be great.


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## thestartupman (Jul 25, 2010)

James, what about having each unit on a timer, so they can't start at the same time to keep the draw down low?


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## Bellyman (Jul 6, 2013)

Is this for a fridge and freezer that you already own? Or are you interested in getting some energy saver type units? Any idea of how much power you would need to run them as they would run normally? 

I have wondered something kinda similar so I'm interested in the discussion.


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## Gray Wolf (Jan 25, 2013)

Why not put them in your house?


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## thestartupman (Jul 25, 2010)

Yes, in the house would be fine, it still doesn't answer my question on how to run them with no grid power


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## thestartupman (Jul 25, 2010)

Bellyman, I have a couple of small chest freezers now and fridge, but what I am looking to do is find a non grid tied way to freeze and cool food year around. If I butcher up a cow, or a couple of dear, I want a way to freeze them, and keep them cool with out grid power. I would be willing at any kind of solution, even if it means getting, or making new fridge freezer units. Putting them in the house, or outside the house. Build a special building that was designed just for this purpose.


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## Jluck (Jul 26, 2014)

thestartupman said:


> Yes, in the house would be fine, it still doesn't answer my question on how to run them with no grid power


PV panels and or wind generator(s) to charge controller to* batteries*....


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## Bellyman (Jul 6, 2013)

The reason I asked what I did was because if you knew the amount of electricity your specific refrigerator and freezer use on a typical day, it would give an idea of a place to start in figuring out what it would take to provide said power. 

I've known of a few people in the rv world that have dispensed with the high priced and rather small electric/propane refrigerators and gone with energy star type refrigerators and just run them on their solar setups. I don't know of any that do not have batteries as well but most of them are running other things that they use all the time, too... computers, lights, televisions, that kind of thing. 

Those that are smart about it, though, will carefully track their usage over a period of time so that they have some idea how big of a system will do what they need it to do. Without knowing what you're going to run, it's a guessing game to know how big of a system you'll need.

James may be right about a cooling system not being able to keep food very well if the freezer (or refrigerator?) can't come on when it needs to. I had thought that temperatures in something like a large chest freezer would be pretty stable overnight with no power but I've never heard of anyone actually tracking the temps to see just what they would do if a) allowed to operate normally or b) only allowed to operate during certain (like daylight) hours. It would be interesting to see such if anyone has already done it. (I haven't Googled it.)


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## K.B. (Sep 7, 2012)

If you have the budget for it, the sunfrost models are very energy efficient. The R19 frig is rated at 330-560 watt-hours/day:
http://www.sunfrost.com/R19.html

This load could be handled on a pretty modest sized PV system with battery/generator backup. 

If jugs of water or other methods to incorporate thermal mass into the system are used, it should also help reducing cycling once the system has charged/cooled.

I have come across people's descriptions of systems where timers are used to limit the energy usage of appliances such as frig/freezers at night. I am tempted to try this, but I wonder what the impact would be on the overall life of the unit (good or bad).


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## K.B. (Sep 7, 2012)

FWIW... Sundanzer brand freezers have been discussed as being suitable for a "battery-free" system. This is discussed briefly at the bottom of the link below:
http://www.survivalunlimited.com/sundanzer.htm


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## Rick (May 10, 2002)

Why not can the meat?

Keeping the system as small as possible will be vital.

Batteries are unavoidable. I wish it was different.

My L 16's and Sundanzer are 6 or 7 years old. I dread replacing the batteries.

This last winter when it was minus 9 deg F, the unheated "bunkhouse" got to 22 deg F at times and the compressor oils got stiff, so we shut it down while it was that cold.

Sundanzer said it would not harm the freezer - just would cycle on and off differently.

I just saw KB's comment on SD running without battsand will check out the discussion. I do know they hold the cold!


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## Jim-mi (May 15, 2002)

The SunDanzer is the answer to your request. They will run very well on only the PV panels---------as long as the sun is shining......
So a small inverter generator would be needed for prolonged periods of no sun.

But . . . .adding a couple batteries a controller more PV panels would be a sweet thing.

And of course super restricting of "opening" the units during non sun hours.

My SunDanzer freezer is just run off the 24v battery bank


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## Gray Wolf (Jan 25, 2013)

Lots and lots of offgrid homes out there. Ours is one. It's just a matter of figuring out what you need and then having the $ to do it. No need to get too trick with your system, just size it to what you actually need to run....then you will want to run more - it works that way for most people.

You can always add panels (if you start with an oversized charge controller) but batteries are different. Start out with at least enough to start as adding new batteries to old will soon bring the whole bank down to the level of your oldest/worst battery.

Inverters can be upgraded. But better to start oversized. Start with sine-wave if you can. Motors, computers, printers, etc. will work better.


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## K.B. (Sep 7, 2012)

fyi... better link on the "battery free" Sundanzer:
http://www.sunshineworks.com/sundanzer-bfr105-solar-refrigerator.htm


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## lynnemabry (Dec 28, 2013)

I believe that you should rethink the battery part. We have a small system, around 600 watts of panels that feed into 4 200 amp hr batteries. Until last year we only had 2 batteries and it was hard to have enough power to run the fridge ( old rv model) and freeze ( new chest freezer). Even turning it off at night wasn't enough. Especially when it gets hot out. 
Plus I bet the cost of batteries would be less that the cost of super insulating a building.


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## thestartupman (Jul 25, 2010)

My biggest reason for wanting to avoid batteries, is because it is one of the items that needs replacing more frequently. So if there was a way to keep the system as simple as possible, even if it cost more up front, I think it would be worth it. I just figure if the grid went down long term, the items that I would need, or want, would be to have fridge, and a freezer. The want part would be to have a A/C unit. ( I don't sleep well at all in the hot summers). I know if I finally get tired enough, I will sleep.


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## Jim-mi (May 15, 2002)

It is easy with many bucks to get the solar powered SunDanzer fridge and freezer up and running.

Only problem is you have to admit that in MO you are going to have sun-less days.

As good as the SunDanzer's are, still asking for 4-5 whatever, days in between charging is a bit much.

Answer is batteries......


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## artificer (Feb 26, 2007)

lynnemabry said:


> I believe that you should rethink the battery part. We have a small system, around 600 watts of panels that feed into 4 200 amp hr batteries. Until last year we only had 2 batteries and it was hard to have enough power to run the fridge ( old rv model) and freeze ( new chest freezer). Even turning it off at night wasn't enough. Especially when it gets hot out.
> Plus I bet the cost of batteries would be less that the cost of super insulating a building.


This sounds like my system. (4) 145watt pannels, Midnite Classic MPPT charge controller, (4) G2 golf cart batteries, Xantrex 2000watt pure sine wave inverter, and a 19.1cubic foot refrig/freezer.

Uses half the capacity on really hot days in an uninsulated shed. (I use 50% dod for calculations)

I would suggest getting Energy Star rated units instead of the Sundanzers, and put the savings into batteries and larger solar panels.

Michael


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## Jim-mi (May 15, 2002)

The big advantage of the SunDanzers is superior insulation. All the walls are at least 4" thick.
No other units come close to that . . . . .Other than Sunfrost which are the top dog for insulation and Danfost compressors.
Sunfrost is twice the money of SunDanzers..

Tho they may be "energy star" rated they do not come close to having all the insulation that SunDanzer has.
The money spent for the better insulation will be money well spent in the long run.


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## jwal10 (Jun 5, 2010)

We have the small freezer and small refrigerator, Sundanzer brand. The refrigerator is in the cabin the freezer is in the springhouse. The refrigerator uses more electricity, it runs off the 24v microhydro. The freezer runs off PV. We have 2 panels and 2 batteries. The microhro system also has 2 batteries. It charges the batteries and the power comes from them. Batteries not needed but it works better this way, we can draw for other things and easy when down for maint. Also can tie both together IF needed. We have had the freezer nearly a year. Was at the beach cottage all winter in a small unheated storage building, full of fish, on a 2 panel, 2 battery system. Even with all the cloudy days we never had to start the generator and we used power for other things, although very minimal. It is now in the storage/fruit house part of the springhouse, very even temp, 44 to 48 degrees, year around. Insulated with sawdust and good humidity control. It doesn't run much. We limit access to once a week and being chest type they do not dump cold air on floor each time they are opened. Need good plan, top layer all in baskets, bottom in paper grocery bags. We have a list for what is where for quick selection....James


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## thestartupman (Jul 25, 2010)

Great information James. Thanks


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## ronron (Feb 4, 2009)

I have been thinking about an evaporation cooler in the basement, very thickly insulated walls with the interior the exact size as refrigerator racks, with a thick door. Tall skinny cooler with a pvc coming in at the bottom of the cooler and a vent pipe out the top the two bottom racks would have flat pans filled with water off set, as the air passes by it cools the contents. We had something similar when I was a child and it worked great.. Might need a small fan in the pipe to get it to draw or a tall exhaust pipe.. The one we had when I was little had cement block walls that were painted and a free standing wooden rack dad eventually replaced the wooden shelving rack system with old refrigerator racks. I remember my mom taking it apart every summer and washing and painting everything.. They kept produce, extra milk, defrosting meat, she would hang her chickens in there to age after butchering, mostly used as an extra refrigerator.. Dad kept cow meds in there too... Theirs wasn't in a basement it was in the corner of our milk house... I am wondering if you could try something like this with an old refrigerator first to see if it would work for you, some sort of vent in through the bottom and a tall exhaust pipe to get the air to draw and a couple of pans of water. Might be worth a try before going to a lot of expense.. Google evaporation refrigerator ..


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## ronron (Feb 4, 2009)

Another thing you can look into is the possibility of rent a meat locker, or you could possibly make a deal with a small local store to put a small freezer in the back of their store for a small fee.. Our little local store would let you rent a space for a freezer for a small fee, they are always looking for ways to make extra money...


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## katlupe (Nov 15, 2004)

I second the SunDanzer! We lived for six years with no refrigerator and before that we had a propane one. Presently we only have the refrigerator, but soon we will buy the smaller freezer (I can most everything, even meat). It is in our pantry and all last winter, I never heard it run once. It uses less power than my energy efficient laptop. It keeps everything really cold too. I think batteries are essential to your system. Our batteries we have had for years. I figure some day we will be replacing them, but I can't imagine not having any.


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## lynnemabry (Dec 28, 2013)

thestartupman said:


> My biggest reason for wanting to avoid batteries, is because it is one of the items that needs replacing more frequently. So if there was a way to keep the system as simple as possible, even if it cost more up front, I think it would be worth it. I just figure if the grid went down long term, the items that I would need, or want, would be to have fridge, and a freezer. The want part would be to have a A/C unit. ( I don't sleep well at all in the hot summers). I know if I finally get tired enough, I will sleep.



Batteries can last better than ten years if you don't over tax them and do the upkeep. Plus we have the flexibility to use other appliances if needed. Although I don't think that a small or modest system can keep up with an air conditioner. That is a really heavy continuous load. A small fan maybe. 

Most of this is learning a new lifestyle and deciding what is important to you. ---- luck.


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## jwal10 (Jun 5, 2010)

My batteries were removed from PLC and computer backup systems at the water plant I worked at. I bought them from the vendor. Removed as regular 4 year changeout maintenance. I have had the batteries in one system for 8 years, the other 4 years. They are a smaller 12v battery, kept charged but were seldom used....James


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## Peasant (May 18, 2013)

Here's some math I recently did on the OP's question:

RUNNING A 5 CF FREEZER AND CONVERTED FRIDGE

220	KWh/year for Kenmore 5.0 cf freezer (listed rating)
200	Wh/day for converted freezer with Johnson controller (average based on internet searches)
73	KWh/year for Kenmore 5.0 cf converted fridge
33.2%	Percent draw fridge vs. freezer

803	Watt-hours per day to run both fridge and freezer
67	Amp hours per day @ 12V

*268 amps 12V battery capacity* to run fridge and freezer (to 75% SOC daily)
45	amps required for 13% charge rate after derate (77% panels to charge controller)
*843	Total solar wattage* (based on rated output of Dmsolar 158W panel)

_Does not include inverter draw or inverter inefficiencies_


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## Shrek (May 1, 2002)

One thing to consider of easy insulation increase is earth. Appliances for cooling kept in a 60 to 65 degree storm pit or cavern will run better off of a 2kw power source regardless of its origins.


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## gpforet (Dec 24, 2013)

Here's what I did for a small deep freezer:

I purchased a Danby 8.2cf energy star freezer which needs right at 900w/24hrs to keep running.

2-250w solarworld panels
1-Midnite Solar Kid MPPT controller
8-Crown GC-235 batteries in 1 string of 8 batteries for 48v @ 235ah
1-Cotek 1000w/48v inverter. This inverter has a sleep mode.
Disconnect, breakers, fuses, cable.

This will power my freezer for a little more than 3 days with no sunshine.

Costs were:
Energy Star Freezer: $430
Solar Panels and mounting hardware: $700
Batteries: $950
Charge Controller: $300
Inverter: $350
Breakers, disconnect, fuses, cabling, battery box: $200

Total: $2,930

I'll get the 30% fed tax rebate on the solar part so actual cost (including freezer) will be $1,930.

And that's to just run the freezer 



Jluck said:


> PV panels and or wind generator(s) to charge controller to* batteries*....


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## thestartupman (Jul 25, 2010)

Well, its been about a year since I first brought this topic up. Has there been any other thoughts and ideas on how to get this up and running? Again, my thought is to get a fridge, and freezer running on a solar only system, using no batteries. The reason for this is to minimize the items that may need replaced, like batteries, and charge controllers.


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## blufford (Nov 23, 2004)

I wonder if an Icyball would be an option.


https://en.wikipedia.org/wiki/Icyball


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## TnAndy (Sep 15, 2005)

thestartupman said:


> Well, its been about a year since I first brought this topic up. Has there been any other thoughts and ideas on how to get this up and running? Again, my thought is to get a fridge, and freezer running on a solar only system, using no batteries. The reason for this is to minimize the items that may need replaced, like batteries, and charge controllers.


Can't do it is why you've gotten nowhere with it. 

Solid cloudy days aren't your problem...sure, you could fire up a generator......it's the sunny days where *ONE* cloud passes over and cuts your panel output to the point your motors on the units burn out....THAT is why you have batteries in the system....they act as a reserve for those periods, as well as cloudy days (as long as the batteries last) and night time.

Also, HOW would you monitor PV panel output ? Say it's a totally cloudless day....what time in the morning do your panels start producing enough to run your equipment ? 8:30 ? 8:47 ? 9:04 ? 

The power curve on a panel is a bell shaped curve....starting at nothing at daylight, building to the max at solar noon, and falling back off to nothing at sunset. If you simply connected the panels somehow thru a grid tie type inverter (which requires no battery/charge controller), your power output curve will be exactly the same. So for the first hour or so of production, it might be enough that your motors TRY to start, but can't for lack of voltage or amps. Brownout. 

Do you plan to sit there and watch a gauge every sunny day and connect the system at some reading ?

You see the problem ?


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## HermitJohn (May 10, 2002)

http://learn.eartheasy.com/2012/07/our-simple-diy-home-solar-power-system/ This isnt exactly what you want and its not in location you live. Cloudy days do matter. But its real world system in use and give you an idea. Sometimes all the theorizing just complicates things.


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## Bellyman (Jul 6, 2013)

TnAndy said:


> Can't do it is why you've gotten nowhere with it.
> 
> Solid cloudy days aren't your problem...sure, you could fire up a generator......it's the sunny days where *ONE* cloud passes over and cuts your panel output to the point your motors on the units burn out....THAT is why you have batteries in the system....they act as a reserve for those periods, as well as cloudy days (as long as the batteries last) and night time.
> 
> ...


Good post, Andy!

It's fun to think about but it just doesn't work out so well in real life.


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## SteveRobertson (Aug 27, 2015)

Everyone is right, you can't do it without batteries. You need something to act as a shock absorber to your power that will supply startup surge and carry through the low-ends of the power curve, as well as store excess power during peak production. A small battery will work.

Back in the 80's and 90's I used the only electric fridge that would run on solar - 24vdc Sunfrost fridge, but it was only 12 cu ft. Today I have a 25cu ft Tier 3 Energy Star fridge that runs great on my system.

My old Sunfrost was 12 cu ft and consumed 0.5kwh per day.
My tier 3 fridge from Sears is 25 cu ft and consumes 0.98kwh per day, and it also has an ice maker!

When you go to the store, look for a fridge that uses 375kwh per year or less on the yellow Energy Guide label. If all you run is the fridge via a 12VDC 400w inverter, two 200 watt panels and 100 amp hour battery would run it in here in Colorado. I have my fridge on a timer to shut it off at 10:00pm, and then back on at 6:00am. It's thick insulation keeps the temperature from reaching an unhealthy point.

IMO LG's fridge with their linear compressor is by far the best. Very little start up surge, and really efficient. Nice thickly insulated walls.


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## gpforet (Dec 24, 2013)

Still the same problem as described earlier: What do you do about days when the sun doesn't shine? Even here in Georgia there are times in the winter when my 235ah 24v battery bank gets down near 50% discharge after 3 days of dreary weather. And that's with 2-250w panels.


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## Bellyman (Jul 6, 2013)

gpforet said:


> Still the same problem as described earlier: What do you do about days when the sun doesn't shine? Even here in Georgia there are times in the winter when my 235ah 24v battery bank gets down near 50% discharge after 3 days of dreary weather. And that's with 2-250w panels.


There are only so many options. A bigger system might carry you longer. Otherwise, you'd either have to shut down the refrigeration or figure out how to add to your battery bank in some other way. Could be wind, hydro or generator of some kind. 

One thing I do wonder about, and maybe Andy or some of the other solar gurus can offer some thoughts, is how much power do you get from a PV panel on a cloudy day? I know they do produce something with lower light levels but I don't have any concept of how much. The reason I would ask such a question would be because I wondered whether adding an extra panel or two to the system would even make a difference on cloudy or rainy days or whether it would be so small of a difference as to not be even worth considering.


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## Dan in Ohio (Jul 16, 2005)

Bellyman said:


> One thing I do wonder about, and maybe Andy or some of the other solar gurus can offer some thoughts, is how much power do you get from a PV panel on a cloudy day? I know they do produce something with lower light levels but I don't have any concept of how much.


On my 3.7kW system, the gray (cloudy) days of winter are between 0.8 kW and 1.5kW total per day. That might not sound like a lot, but I can run my freezer and my woodstove fan all day on the low end of that . . . and I still have a big backup battery behind that. So it is meaningful generation to me.

That doesn't count the days the array is covered with snow of course . . .


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## wy_white_wolf (Oct 14, 2004)

Bellyman said:


> There are only so many options. A bigger system might carry you longer. Otherwise, you'd either have to shut down the refrigeration or figure out how to add to your battery bank in some other way. Could be wind, hydro or generator of some kind.
> 
> One thing I do wonder about, and maybe Andy or some of the other solar gurus can offer some thoughts, is how much power do you get from a PV panel on a cloudy day? I know they do produce something with lower light levels but I don't have any concept of how much. The reason I would ask such a question would be because I wondered whether adding an extra panel or two to the system would even make a difference on cloudy or rainy days or whether it would be so small of a difference as to not be even worth considering.


 On heavy gray cloud days I see less than 5% of what they normally put out. On light whispy cloud times I still see 25 to 50%.

WWW


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