# Solar Practical Application for Dummies



## Gruntz03 (Jun 3, 2015)

There are so many threads on solar power to go through that it can get overwhelming. 
I was hoping one of the experts on here could help me with a solar setup for a specific purpose. I would like a setup that would run a chest freezer and only a chest freezer off grid. I have found this one:
GE 10.6 cu. ft. Chest Freezer in White-FCM11PHWW - The Home Depot

The energy guide says that it will consume 218Kwh over 1 year. I know this is an estimate, but lets take it as gospel for this thread.
So, 218x1000=218,000Wh per year

218,000/365=597Wh per day. Lets round up to 600.

Where do I go from here? My novice thinking is: 600/4 hrs peak sun=150w. So, 1 150w solar panel.

Right or Wrong?

Batteries?

Charge Controller?

Please no fancy words or big math.


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## 8301 (Nov 29, 2014)

If you average about 5 strong hours of sunshine per day (national average is 5.4 hrs) and you're system is 85% efficient you'd need about 130 watts worth of solar panels minimum. Since winter days are shorter I'd suggest 180+ watts worth of panels, Amazon.com with free shipping is probably your best deal for panels and a simple 30 amp charge controller.

batteries,,, you really want to try to avoid draining your batteries down below 50% charge (12.1v resting) Now it could rain hard for 3 days so if you have three deep cycle 100 amp/hr (20 hr discharge rate) (Auto Zone about $130 each) you should be able to run the fridge for 3 full sunless days, or just get two batteries and realize that occasionally you're really going to dip it low a few times a year. One of those 100 amp/hr batteries can almost run your fridge for 2 days but it will really shorten the life of the battery. Personally I like better quality batteries but they are expensive.

Inverter: I have the same freezer but one size smaller and it easily runs off of my 1000 watt inverter so I'd suggest going to the truckstop (or Amazon) and getting a 1500 watt inverter. Big enough to run the fridge and a few small extras but small enough to keep the wiring easy. A high quality 1200 watt inverter should run that freezer.


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## Gruntz03 (Jun 3, 2015)

FoolAmI said:


> If you average about 5 strong hours of sunshine per day (national average is 5.4 hrs) and you're system is 85% efficient you'd need about 130 watts worth of solar panels minimum. Since winter days are shorter I'd suggest 180+ watts worth of panels, Amazon.com with free shipping is probably your best deal for panels and a simple 30 amp charge controller.
> 
> batteries,,, you really want to try to avoid draining your batteries down below 50% charge (12.1v resting) Now it could rain hard for 3 days so if you have three deep cycle 100 amp/hr (20 hr discharge rate) (Auto Zone about $130 each) you should be able to run the fridge for 3 full sunless days, or just get two batteries and realize that occasionally you're really going to dip it low a few times a year. One of those 100 amp/hr batteries can almost run your fridge for 2 days but it will really shorten the life of the battery. Personally I like better quality batteries but they are expensive.
> 
> Inverter: I have the same freezer but one size smaller and it easily runs off of my 1000 watt inverter so I'd suggest going to the truckstop (or Amazon) and getting a 1500 watt inverter. Big enough to run the fridge and a few small extras but small enough to keep the wiring easy. A high quality 1200 watt inverter should run that freezer.


What about charging those 3 batteries? 1 180w panel does not seem like enough.


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## Stick (Sep 29, 2014)

I have four 100 watt panels to four marine batteries. Running a computer, lights, phone, hot spot, and a Grape Solar 12v 2.5cf freezer. Occasionally charge other stuff, or run an amp, guitar and mike. My first Grape freezer wouldn't get below 28 degrees, so they sent me a new one that works great. Will set up the first one as a refrigerator with another battery and panel. After three years in the desert with no refrigeration cold water has been a major luxury this past summer. Sometimes I just sit around in the shade and drink ice water. Pour some on my head. Ahhhhhhhhhhhhh.....


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## 8301 (Nov 29, 2014)

Gruntz03 said:


> What about charging those 3 batteries? 1 180w panel does not seem like enough.


True, 180 watts of panels is pretty marginal for fully charging 3 batteries of that size but it is sufficient. I was trying to provide just the minimum to meet your .6 kwh daily requirements as you requested in the original post. Personally I'd like to see 400+ watts worth of panels to be able to top off your batteries faster but you don't need that many panels to meet your minimum requirements.


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## CrackPot (Nov 11, 2014)

Another consideration is the battery storage's run duration. Here in the Northeast we can go 4-5 days in a row without full sun. As a result I sized my battery storage to be 2x my maximum draw. As an example, over the past 5 days I have generated 173Ah, 33Ah, 267Ah, 50Ah, 167Ah (in percentages of normal generation during that period: 69%, 12%, 100%, 19%, 62%). Without consistent sun you could run down your batteries to the point the inverter kicks off for low voltage and then your freezer thaws your food which promotes bacteria growth. By having 2+ days of battery I can go with 4 days of 50% generation in a row without hitting the low voltage limit.


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## Gimble (Aug 14, 2015)

I was going to suggest a DC/Solar Compatible freezer, but FoolAmI beat me to it... Even if the freezer costs more, it might cost less if you factor out the inverter and reconfigure the batteries. Although you're likely to use the inverter for other things.


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