Lantley wrote:
We are not talking an industrial setting or 15K active devices.
What does that have to do with RV's? And you think I'm on some stuff...LOL
You are correct you would have to cover the roof in panels.
But believe or not solar enthusiast are covering their roof in panels.
The roof space is available. The genset compartment of my RV could hold 10-12 batteries easily..
I'm not trying to run A/C 24/7 on batteries. I don't need to.
I don't run my A/C with my Onan 24/7.
Running it overnight would be my goal and recharge during the day.
Worst case one would have a 2000 watt genset available for cloudy days...LOL.
I undesrstand solar A/C is not perfected, but its not a pipe dream either.
Back in 2012 when I factory ordered my genset solar A/C was a pipe dream. However in 2022 it is a viable option.
Give it 10 more years and it will likely be a OEM factory available option.
The one thing I can be sure of is the technology won't stand still.
I've seen enough game changing technology in my lifetime, especilally the last 20 years. That solar powered RV A/C is not that mind boggling at this point.
OK, so, lets do some "back of the napkin math" for real world right now.
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.
Solar only charges when there is sufficient sunlight strength, just because you have daylight, does not mean you are getting a full charge or even a charge at all. The further you are away from the Equater, the less Insolation you get. In the USA that means about 5 peak charging hrs provided you have no clouds and no grey overcast weather.
Please, follow along very closely.
Running RV A/C from solar/battery
From a 24DC RV A/C manufacturer I found, their A/C is 12,000 BTUs, draws 21A max or 1,008W
They recommend 2,500W in panels for 24 hr operation. That is 2.5x the max running watts.
13,500 BTU RV A/C draws 13A at 120V or 1560W.
1560W x 2.5=3,900W, to make things easier we will round this to 4,000W or 40 100W panels
13A at 120V is roughly 130A at 12V, run that for 1 hr is 130Ahr for each hr run.
24hrs=3120Ahr,
But with solar, 3 days worth of battery capacity is used to cover bad weather days.
3 x 3120 = 9360 Ahr or 93.6 100Ahr batteries (we will round that to 94 100Ahr batteries)
100W solar panels 40 x 20 (we will round this to 4’ x 2’ or 8 square feet each panel for easy math), weigh about 15 lbs each, $1 per watt cost= 100W panel cost at $100.
40 x 8 = 320 square feet of roof or equivalent to a RV roof of 8ft wide and 40ft in length.
40 x $100 = $4,000
40 x 15 = 600 lbs
Best lithium battery price I can find is $269 for 100Ahr, needs roughly .5 square ft per battery, life cycles rated 3,000 to 7,000, weight is 26 lbs each
We need 94 100Ahr batteries, roughly 47 square ft of storage space.
94 x $269 = $25,286
94 x 26 lbs = 2,444 lbs
3,000 cycles/365 = 8.2 yrs life (I have found through experience that most lithium battery manufacturers way overstate the life cycles)
System cost for panels and batteries
$4,000 + $25,286 = $29,286
System added weight
600 lbs + 2,444 lbs = 3,044 lbs
But, wait, that does not include solar panel controllers, wiring or inverter costs, not to mention will not fit on sub 40ft RV roof without some exotic hinge/drawer system and a 40ft RV will need more than one 13.5K BTU A/C to keep it in some sort of comfortable range putting you into a solar and battery capacity deficit.I can buy a lot of gas for a $250 generator even at $5 per gallon..
Most RVrs are not going to recoup or break even on that kind of cost.
So, unless you are 100% full timer the math doesn't add up to make good financial sense.
