Solar Powered RV

Hi mena,

I just checked the Dometic pdf. The 13500 draws 12.4 amps plus 3 amps for the fan. Locked rotor is 63 amps. The 15000 draws 13.3 amps plus 2.8 amps for the fan with locked rotor at 66 amps. My air conditioner is a Dometic from 2004 and is 13500 btu's. I was comparing apples to apples with the about the same cooling capacity. I do admit the 1200 came from measurements of my own unit.

(drat this is making me "rethink" the size of inverter I need :( )

Last time I check 60 x 3 = 180 amps? (typo yes?) but I agree 2 x 9 = 18 = 25% more cooling for the same amps.

mena661 wrote:
You keep thinking everyone has YOUR A/C unit when most everyone has a standard 13.5k or 15k BTU unit and the 13.5k's draw about 120 amps and the 15k's draw 150 amps. With a standard 15k unit, there would be a 50 amp savings.

They have a rooftop 9k unit that draws 720W in either 12 or 24V. Say it's 12V, that's 60A. Three of those would provide 27k of cooling and draw as much as ONE 13.5k unit.

Hi Almot,

I don't think so. I think 1900 watts of panels and 8 group 31 agm batteries would be enough for a 12.4 amp (plus 3 amps for the fan) 13500 btu air conditioner. The pre break even and post break even times are "outside" the six "peak" hours. During the six peak hours about 400 watts are going to be deposited in the "bank" per hour.

One would have to be creative about deployment of the panels.

Almot wrote:

Ok, so we are down to 2,500W solar array - tiny, 7ft by 25ft :)


The effect of such an A/C will be tiny as well.

And a small 500 AH bank that will be half-empty by the morning and if there is no sun - let's assume the unlikely scenario, clouds next morning :) - there comes a generator.

Hi mlts22,

That would be the Magnum line--currently available @ 24 volts, and soon to be released for 12 volts. The Victron appears to be a bit cheaper and has been around for ages.

mlts22 wrote:
I forgot the brand, but a hybrid converter/inverter (Victron has these as well, but I forgot the brand that just came out) which allows something like an A/C or microwave to run off a generator, but the inrush current be handled by both the generator as well as the inverter for a brief time, then the generator handles the load.

pianotuna wrote:
Hi,

Smallest air I've seen is about 4500 btu's. That would draw 30 amps @ 12 volts. 30 x 8 hours = 240 amp-hours.

Ok, so we are down to 2,500W solar array - tiny, 7ft by 25ft :)


The effect of such an A/C will be tiny as well.

And a small 500 AH bank that will be half-empty by the morning and if there is no sun - let's assume the unlikely scenario, clouds next morning :) - there comes a generator.

pianotuna wrote:
Hi mena,

Where is the 50 amp savings? My AC draws less than 1200 watts. Inverter losses are about 12% so the savings are 12 amps?

You keep thinking everyone has YOUR A/C unit when most everyone has a standard 13.5k or 15k BTU unit and the 13.5k's draw about 120 amps and the 15k's draw 150 amps. With a standard 15k unit, there would be a 50 amp savings.

They have a rooftop 9k unit that draws 720W in either 12 or 24V. Say it's 12V, that's 60A. Three of those would provide 27k of cooling and draw as much as ONE 13.5k unit.

qtla9111 wrote:
I don't think it is so much the class of the motorhome but for people to know that there are advances in technology. Whenever a thread starts about solar and A/C it is poo-pooed from the start by many people who are just not in the know.

Solar and batteries have come a long way. I know of three people who power their rvs A/C with batteries and solar but they refuse to post here because they always get shot down.

As someone else said, how about looking for an alternative by using a smaller unit with a smaller draw that will keep you cool in your bedroom at night.

These threads always go bad, they don't need to. Be more open-minded and accept the fact that the world doesn't have to exist solely on 110 and fossil fuel. A big mistake was made over 100 years ago when they refused Tesla's proposal.

There is a Youtube video maker whom I follow, who is running a small (5000 BTU) A/C off of a few solar panels. It isn't the best setup, but it allows him to run the A/C to help cool/dry the air for a couple hours in the evening.

Eventually we will get to a point of being able to run an A/C off a larger rig's solar panels. It will take some inventions such as a slide-out mechanism for more square footage for panels to use, better charge controllers (perhaps each individual cell in a panel would have a small regulator, which would cause the energy loss from shade to be as low as possible), better batteries (supercaps, lithium/air), and maybe even advances in wiring. A superconducting wire the thickness of a thread would replace a pretty thick wire, if room temperature superconductivity can be achieved with a ductile material.

There are some cool innovations coming out now. I forgot the brand, but a hybrid converter/inverter (Victron has these as well, but I forgot the brand that just came out) which allows something like an A/C or microwave to run off a generator, but the inrush current be handled by both the generator as well as the inverter for a brief time, then the generator handles the load.

Hi,

Smallest air I've seen is about 4500 btu's. That would draw 30 amps @ 12 volts. 30 x 8 hours = 240 amp-hours.

240 amp-hours in 20 minutes implies charging at 720 amps. That would take 18 pd 40 amp chargers which would draw about 12600 watts @ 120 volts.

Or if we go to 48 volts it is still 60 amp-hours X 3 = 180 amps

I don't think it's a portable charger LOL.

Hi mena,

Where is the 50 amp savings? My AC draws less than 1200 watts. Inverter losses are about 12% so the savings are 12 amps?

I don't think it is so much the class of the motorhome but for people to know that there are advances in technology. Whenever a thread starts about solar and A/C it is poo-pooed from the start by many people who are just not in the know.

Solar and batteries have come a long way. I know of three people who power their rvs A/C with batteries and solar but they refuse to post here because they always get shot down.

As someone else said, how about looking for an alternative by using a smaller unit with a smaller draw that will keep you cool in your bedroom at night.

These threads always go bad, they don't need to. Be more open-minded and accept the fact that the world doesn't have to exist solely on 110 and fossil fuel. A big mistake was made over 100 years ago when they refused Tesla's proposal.

MNtundraRet wrote:
Mena:

The Class B information came from an early replier claiming a Class B manufacturer had an electric option model that could run the air-conditioner for 8 hours, and recharge the battery-bank in 20 minutes.

That's where I came in asking for a link to check his claim.

Mark B.

Gotcha. Thanks for the clarification.

Francesca Knowles wrote:
As if that matters...new here, are you? ;)

LOL! Feeling a little newb-ish today. :B

pianotuna wrote:
Hi,

Their 13500 btu unit draws 1200 watts (600 watts 50% duty cycle), so it appears to me the savings are only on the inverter losses.

Ah, very true. Still 100A on the batteries at full load which would be the case if I'm running the A/C. You do save about 50A.