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Solar needs

RV Jim

Newbie needing help
Joined
Mar 29, 2022
Messages
39
Location
Odem Texas
The question is how do I determine what is exactly needed to run a 1300 watt portable 120 volt air conditioner. I am an absolute newbie at this. Here I the story, I'm in the process of converting a cargo trailer to a camper. It will have "shore power" but want the flexibility of DC as well. I am a little confused with how to determine what is needed...thanks in advance for the help. P.S. the cargo trailer(previously owned) I am in the process of purchasing has 400 watts of solar panels on the roof now.
 
needed to run a 1300 watt portable 120 volt air conditioner.
You will need a battery to store this power.
Converting DC to AC is about 85% efficient so...

1300W / .85 = 1530W running

To run for 1 hour, you need a battery with 1530Wh of storage. For 5 hours, 7650Wh.

1530Wh / 12.8V battery = 119.5Ah battery (double that for lead acid because only 50% dischargeable, down to 12V)
7650Wh / 12.8V = 598Ah (x2 for lead acid)

Recharging with 400W solar:
1530Wh / 400W = 3.8h operating at 100% (unlikely)
7650Wh / 400W = 19.2h

Consider an average solar day to be about 5h in the summer, less in winter, particularly away from the equator.
 
1300W is a lot to run on battery/solar.

Some math: Let's assume the 1300W A/C uses that much power 20 minutes every hour. That's a 33% duty cycle. Let's say you wish to run the A/C for 6 hours per day. That works out to 1300W x 33% x 6 hours = 2600Wh (watt hours).

You have 400W of solar panels. Let's pretend you can actually get the full 400W out of them (you can't).

2600Wh / 400W = 6.5 hours. This means you need 6.5 hours (probably more like 8 or 9 in real life) of good solar conditions each day for your solar panels to power your A/C. Even places like AZ or FL don't get that much solar each day.

And none of this takes into account any other loads you might need such as powering a refrigerator and lights and a water pump, etc.

None of this deals with a day or two of clouds.

You either need a lot more solar panels or you need a much more efficient A/C such as a mini split. Probably both.
 
I guess I'm still confused. I'm thinking about either 2 100 ah or 1 200 ah batteries with an inverter to power the AC. Is that feasible? I also would like to use 12v for a roof fan, led puck lights yet to be determined with some outside lights yet to be determined. I plan to purchase a 2000 ish watt generator as a when all else fails or no shore is available. This being a newbie really sucks...thanks to all who have replied for my cries for assistance.
 
12V 200Ah is 2580Wh. That would run a 1300W A/C for 2580Wh / 1300W = 1.98 hours.
 
1300W is a lot to run on battery/solar.

Some math: Let's assume the 1300W A/C uses that much power 20 minutes every hour. That's a 33% duty cycle. Let's say you wish to run the A/C for 6 hours per day. That works out to 1300W x 33% x 6 hours = 2600Wh (watt hours).

You have 400W of solar panels. Let's pretend you can actually get the full 400W out of them (you can't).

2600Wh / 400W = 6.5 hours. This means you need 6.5 hours (probably more like 8 or 9 in real life) of good solar conditions each day for your solar panels to power your A/C. Even places like AZ or FL don't get that much solar each day.

And none of this takes into account any other loads you might need such as powering a refrigerator and lights and a water pump, etc.

None of this deals with a day or two of clouds.

You either need a lot more solar panels or you need a much more efficient A/C such as a mini split. Probably both.

That's still not too bad, basically just a $200 400w panel away from changing "probably not" to "probably could". Plus, while clouds might mean reduced solar output, it also probably means reduced need for that solar output.
 
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