# What size inverter to use?



## budgetprepp-n

Hi,
I am getting ready to ad some solar panels to my set up and I'm figuring to make use of them. I been looking at
the small freezer chest like about 3.5 cubic feet. They are easy to convert to a refrigerator.
This seems to be a very easy conversion. This seems to be the way most people that run solar are doing it.
My question is what size inverter do you think this would take? How many watt?


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## pheniox17

you need a full sin wave inverter, these are very expensive...

its because of the compressor... inverters can't run them properly... 

the cost of inverver + battery storage, it will be more cost effective to purchase a 3 way fridge/freezer

if I were you... abandon this project before it gets far to expensive, and look in the 2nd hand camping market for a 12v unit


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## budgetprepp-n

pheniox17 said:


> you need a full sin wave inverter, these are very expensive...
> 
> its because of the compressor... inverters can't run them properly...
> 
> the cost of inverver + battery storage, it will be more cost effective to purchase a 3 way fridge/freezer
> 
> if I were you... abandon this project before it gets far to expensive, and look in the 2nd hand camping market for a 12v unit


The 3 way refrigerator your running now how long will it run on your battery bank and how big is the bank?

I gave $150 for my 1500 watt pure sine wave inverter (new) that I have now to run the TV computer and didn't think
that was that expensive. 
I don't know if the inverter I have now is big enough or not. 
I can buy a brand new 3.6 upright freezer and the conversion kit for $200 or less-
So I'm really hoping the inverter I have now is big enough-- I have never messed with anything like this before.

I have been hitting some solar forums and they are telling me not to go with a 12 volt out of camper they use to much juice
And if you want a very efficient 12 volt refrigerator they start around $1,000 and up. Unless I use one that is like a big cooler 
and they are costly also. A decent one runs about $500 or up (ouch)

But on the other forums for solar I'm having a problem getting a straight answer on the Inverter.
Most of those guy are trying to figure everything right down to the .000000000000000000000000000000001 of a watt
I'm thinking they must have a feddish for there calculators or something. 
I'm just looking for an anwser in general.

Since I can get everything shinny and new for under $200 + the cost of a new bigger inverter if need one 
this might be the best way.


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## PaulS

A refrigerator uses a lot of power to start and then lower power when operating. The compressor motor can use up to ten times the amps to start as it needs to run. Your inverter needs to be able to supply more watts than the motor consumes during the start up period. The motor should have a tag that shows three different power consumptions. You want a converter that handle over the highest usage listed on the motor.

The mat is simple:

Motor start up amps * motor voltage = start up watts. Start up watts should be no more than 90% of your inverter peak power output.


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## budgetprepp-n

PaulS said:


> A refrigerator uses a lot of power to start and then lower power when operating. The compressor motor can use up to ten times the amps to start as it needs to run. Your inverter needs to be able to supply more watts than the motor consumes during the start up period. The motor should have a tag that shows three different power consumptions. You want a converter that handle over the highest usage listed on the motor.
> 
> The mat is simple:
> 
> Motor start up amps * motor voltage = start up watts. Start up watts should be no more than 90% of your inverter peak power output.


Can you get any of that information from the energy guide? 
I don't think it has any stickers that include that information

Igloo 3.6 cu. ft. Defrost Compact Chest Freezer - Walmart.com


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## pheniox17

just going on local prices (looked into it a while ago) the type of inverters your starting price is $1500 and even then its been referred as a gamble on a start up load.. 

the 3 ways (and the 12 volt local) brand name fridges/freezers have glowing recommendations by off the grid types here, and the 4wd crowd... 

but with your TV example, its good (you know can generate enough power to run a high end TV with accessories with a $150 inverter) is great, but when your dealing with compressors (fridge, freezer, air compressor, air conditioner... etc) the rules change... (even ac motors) 

you will always get the you can do it (and you can) when you look closer, the cost is just too high to the benefit 

to awnser how long my 3 way runs, I don't have one... I am no where near off the grid living, but I have also refitted busses as caravans, and helped in "100% solar" homes in design and equipment (it is cheaper here on a new country home to install a solar system than pay to go onto the grid, then upkeep) 

not telling you it can't be done, the coat to do it your better off with a designed 12v unit and a wacol 12v car fridge on 2 small truck bats (not deep cycle) gets 3 days with continuous running (this I have) with no external charge (that includes leaving car off)


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## PaulS

I looked at the ad in your link and found product information and specifications but nothing about start up amps. It should be listed on the motor on a plate or sticker. There should be an access panel that you can easily remove to get that information. You might ask the store to see the motor to see if it will meet your requirements. They used to list the information in the specifications - I wonder why they don't do that here...


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## budgetprepp-n

PaulS said:


> I looked at the ad in your link and found product information and specifications but nothing about start up amps. It should be listed on the motor on a plate or sticker. There should be an access panel that you can easily remove to get that information. You might ask the store to see the motor to see if it will meet your requirements. They used to list the information in the specifications - I wonder why they don't do that here...


Ok is there any freezers that can be found on line for a 3.5 or close just give us an idea?
They don't have it in the store it must be ordered.


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## pheniox17

Paul, start up amps is not normally listed in advertising, same as air con units, depends on the brand it may not even have the info on the plate


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## budgetprepp-n

This is the brand I'm using now and my TV looks better when I use the inverter than it does when I'm
using the grid. I didn't know they were so expensive. 
Pure Sine Wave Power Inverter 1500 3000 Watt DC to AC | eBay


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## pheniox17

budgetprepp-n said:


> This is the brand I'm using now and my TV looks better when I use the inverter than it does when I'm
> using the grid. I didn't know they were so expensive.
> Pure Sine Wave Power Inverter 1500 3000 Watt DC to AC | eBay


$800 is a alright price retail for a pure sin inverters


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## HuntingHawk

The name tag on the product gives the maximum surge amps. My 5cuft initial draw is over 6amps but only for a few seconds then it is 1.69amps.


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## HuntingHawk

Sometimes you can find a deal on a used inverter on ebay but ....


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## budgetprepp-n

HuntingHawk said:


> The name tag on the product gives the maximum surge amps. My 5cuft initial draw is over 6amps but only for a few seconds then it is 1.69amps.


PaulS can you use this information to figure out what size inverter it would take to run HuntingHawks fridge?
It's bigger than what I was going to get but that will get us some leeway.


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## budgetprepp-n

HuntingHawk said:


> The name tag on the product gives the maximum surge amps. My 5cuft initial draw is over 6amps but only for a few seconds then it is 1.69amps.


Ok is it over 7? over 8?


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## budgetprepp-n

HuntingHawk said:


> Sometimes you can find a deal on a used inverter on ebay but ....


But what? This is the one I bought I have seen them go for $100 
I been keeping mine warm for about a year now and it seems fine so far. 
Check it out. I'm running on it right now 
Pure Sine Wave Power Inverter 1500 3000 Watt DC to AC | eBay


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## HuntingHawk

P=EI so 120x6=720watts

So an 800watt inverter should be more then enough.


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## HuntingHawk

The but... part was about buying anything used.


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## budgetprepp-n

HuntingHawk said:


> P=EI so 120x6=720watts
> 
> So an 800watt inverter should be more then enough.


 You know I was just thinking,,,I have a small 800 watt harbor freight gas generator and it 
will run my full size refrigerator. So with 1500 watt inverter with a 3000 surge it should be OK. 
I got enough batteries but my solar panels at 300 watts are going to be weak.
I know the panels won't keep up recharging the batteries but I should be able to tell if the inverter is OK.
If I start out with fully charged batteries it should run a while right?

Oh,,, I'm starting to get that feeling in my stomach that I feel when an experiment is coming on.
But it may be the fish I ate earlier it didn't taste just right.


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## HuntingHawk

My Triplet inverter is a bag, black, heavy monster. I've had it running the chest freezer plus a 10,000BTU AC at the same time just to see if it would. AC is max draw of alittle over 9amps so would be 1080watts initial draw when compressor kicks on. Don't remember if the Triplet is 2,000 or 2,500watt inverter.


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## nephilim

budgetprepp-n said:


> You know I was just thinking,,,I have a small 800 watt harbor freight gas generator and it
> will run my full size refrigerator. So with 1500 watt inverter with a 3000 surge it should be OK.
> I got enough batteries but my solar panels at 300 watts are going to be weak.
> I know the panels won't keep up recharging the batteries but I should be able to tell if the inverter is OK.
> If I start out with fully charged batteries it should run a while right?
> 
> Oh,,, I'm starting to get that feeling in my stomach that I feel when an experiment is coming on.
> But it may be the fish I ate earlier it didn't taste just right.


You'll be surprised. If your cells are in direct sunlight they'll charge batteries up reasonably well, but obviously it is better if you have more to work from. 300w will charge a car battery in around 20 hours of direct sunlight, a solar battery (which is larger capacity usually) will take around double that.

If you use my guide, you can actually make cheap solar panels just using a bit of your time and no more than $100 for a 250w panel. Make a few of these and you should be golden!


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## HuntingHawk

budgetprep, I think the main issue is going to be how much & for how long you get into the chest freezer daily. Latitude adjustment of panels is critical to get the most out of the panels. Mine need adjusted between 15-45 degrees threw the year & adjusted once a month.
And yes it makes a difference. Each month when I adjust the panels I see about a 5amp immediate difference.
Easy numbers lets say 6 hours per day times 30 days would be an extra 900AH per month. Not bad for 10 minutes to get up on te roof & adjust two racks of panels.


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## budgetprepp-n

HuntingHawk said:


> budgetprep, I think the main issue is going to be how much & for how long you get into the chest freezer daily. Latitude adjustment of panels is critical to get the most out of the panels. Mine need adjusted between 15-45 degrees threw the year & adjusted once a month.
> And yes it makes a difference. Each month when I adjust the panels I see about a 5amp immediate difference.
> Easy numbers lets say 6 hours per day times 30 days would be an extra 900AH per month. Not bad for 10 minutes to get up on te roof & adjust two racks of panels.


wouldn't take me 5 minuets 


I sort of had to do it this way,, We get some nasty storms here or in the winter I have seen 
3 feet of snow in 24 hours. They will fold back under the roof if needed. For a lot of snow on 
them I just let them hang straight down and it falls off them


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## HuntingHawk

I think if you check back, I'm the one that suggested those type of rods for being able to adjust the angle.


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## budgetprepp-n

HuntingHawk said:


> I think if you check back, I'm the one that suggested those type of rods for being able to adjust the angle.


 Was that you that sent the home made blueprints for this set up?


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## HuntingHawk

Here is the inverter I have:
Industrial Strength Inverter 2000W 2 Outlets | PV2000FC | Tripp Lite


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## budgetprepp-n

HuntingHawk said:


> Here is the inverter I have:
> Industrial Strength Inverter 2000W 2 Outlets | PV2000FC | Tripp Lite


 Damn that thing looks mean Is this yours?



I used a lot of suggestions from a lot of people when I built this set up 
you get this many people making suggestion you get some good ones 
I didn't do much thinking on this project I just did the manual labor part


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## HuntingHawk

Whomever did the original hinged panels I suggested the way to do the rods for the adjustable angle.


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## Kauboy

I feel it necessary to point out that you don't need a pure sine wave inverter for things that run motors.
Pure sine wave inverters are needed when dealing with intricate electronics are in use, and when broadcasting equipment is being run (radios, televisions, etc...)
If you want to buy a separate inverter for this fridge, to work along side your current one, it doesn't need to be a pure sine wave model.


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## budgetprepp-n

HuntingHawk said:


> Whomever did the original hinged panels I suggested the way to do the rods for the adjustable angle.


 Thank You


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## Slippy

Budget,

You are indeed a thinking man! great job


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