I have an off grid building and want to put 3 15 cu ft freezers in it. I am having trouble calculating for panels, how many and wattage and battery storage. I had originally figured 8 actual running hours for a freezer, but it appears they run 80-90% of the time. So if you have 700 watts times 21 hours that is 14,770 watt hours per day & have 3 freezers which amounts to 44,100 wh. Southern exposure is great. Figure 2 no sun days So how do I determine panels wattage & battery storage neneeded
Sizing for off grid hunting shack
- Thread starter jduns
- Start date
sunshine_eggo
Happy Breffast!
First, check your consumption. You'll shit yourself at the cost to power 44.1kWh/day - that's 1.5X the average U.S. household's energy consumption.
What does the yellow energy star label on them say?
For a 14.8cu-ft Frigidaire chest freezer at home depot: 296kWh/year
296kWh/year = 296/365 = 0.81kWh/day.
3X of that is 2.5kWh/day rounded up.
Note that this standard has changed to simply represent the amount of energy required to power it with the door closed in 90°F ambient conditions. If you open the door, or its hotter, you may use more. If it's colder, you'll use a lot less.
I have a 10.1 cu-ft fridge in a very cold RV right now, and it rarely runs. In the last 24 hours, it has turned on twice using about 60W of power:
For cool down or large mass changes, you can get extended run periods. I'd size for 3-4kWh/day
Second, model a 1kW array at your location on PV Watts in my signature line #1.
That will tell you the average solar hours/day you get by month.
Pick the most appropriate month (usually the lowest) and divide your consumption by that number, e.g., 4kWh/day / 2.5hr/day = 1600W of PV.
Re-run PVWatts for that array to see your actual harvest.
Check link #3 for a prediction on how many days your battery will be empty/full.
You'll need 3-4kWh of usable battery capacity for every 24 hours between charges.
What does the yellow energy star label on them say?
For a 14.8cu-ft Frigidaire chest freezer at home depot: 296kWh/year
296kWh/year = 296/365 = 0.81kWh/day.
3X of that is 2.5kWh/day rounded up.
Note that this standard has changed to simply represent the amount of energy required to power it with the door closed in 90°F ambient conditions. If you open the door, or its hotter, you may use more. If it's colder, you'll use a lot less.
I have a 10.1 cu-ft fridge in a very cold RV right now, and it rarely runs. In the last 24 hours, it has turned on twice using about 60W of power:
For cool down or large mass changes, you can get extended run periods. I'd size for 3-4kWh/day
Second, model a 1kW array at your location on PV Watts in my signature line #1.
That will tell you the average solar hours/day you get by month.
Pick the most appropriate month (usually the lowest) and divide your consumption by that number, e.g., 4kWh/day / 2.5hr/day = 1600W of PV.
Re-run PVWatts for that array to see your actual harvest.
Check link #3 for a prediction on how many days your battery will be empty/full.
You'll need 3-4kWh of usable battery capacity for every 24 hours between charges.
DIYrich
Solar Wizard
Add 1.5 kwh for the inverter (60 watts) per day (5 kwh for 3 days).
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