I am planning to install 12 100 watt solar panels, 2 300 amp lpf batteries, 3000 watt inverter. I want to run a/c for 4 hours so I can sleep when no shore power is available and can't use generator? I will be using a mppt controller but haven't decided how I will lay out the panels yet, volts-amps, 12 volt or 24 volt system. Just starting here. Appreciate any guidance.
What is enough for 4 hours of a/c?
- Thread starter cardog22
- Start date
richard cabesa
New Member
- Joined
- Mar 16, 2021
- Messages
- 185
What kind of vehicle?
How big?
What kind, how much insulation?
Where are you parked?
What temp do you like to maintain?
What are daytime temps?
What night time temps?
What seasons are you camping?
Those are my first off the cuff questions. I can come up with More I’m sure.
There is no straight answer
How big?
What kind, how much insulation?
Where are you parked?
What temp do you like to maintain?
What are daytime temps?
What night time temps?
What seasons are you camping?
Those are my first off the cuff questions. I can come up with More I’m sure.
There is no straight answer
Weekend van
New Member
As noted, need to know the A/C power consumption. A little invertor 6000 btu unit is way different than an old induction motor 5-ton.
datdude
New Member
It will likely use more than that if OP is running off an inverter...efficiency loss.
justinm001
Solar Addict
- Joined
- Dec 18, 2022
- Messages
- 1,910
Ummm. How many acs and what size are they? A shunt will tell you exactly how much it's using. Mine run 1300-1500w and I have 6 ACs so for me it's like 8500w.
Say you have 1 ac 1500w for 4 hours that's 6kwh or 500ah on 12v. The 20% inverter loss should already factored in.
1200w of panels you can hope for 5 hours in a good sun region on a clear day so 6kwh. So if everything's perfect it's just enough to recharge....
AC should be kicking on/off depending on size of RV. In my 40ft I typically leave 1 on constantly in summer all night then another starts if it gets too hot
Say you have 1 ac 1500w for 4 hours that's 6kwh or 500ah on 12v. The 20% inverter loss should already factored in.
1200w of panels you can hope for 5 hours in a good sun region on a clear day so 6kwh. So if everything's perfect it's just enough to recharge....
AC should be kicking on/off depending on size of RV. In my 40ft I typically leave 1 on constantly in summer all night then another starts if it gets too hot
Yeah, forgot that important element, 13500 btu a/c. About 1500 watts per hour. Relatively small trailer 27', 200 square ft. Only plan to use the a/c for one night between shoe power it generator days. Example, Cracker Barrel for a night then to a park for shore power or boondock with generator. This is just a once or twice a week thing when traveling. I could go to a third battery but the batteries would have to be separated and that presents it's own set of issues. Weight is not an issue but space is. Inverter and sc need to cool and there not small.
SouthernSolar
Solar Enthusiast
Are the panels flat mounted on the roof?
Guessing batteries will start at 100 percent if charged while on shore power.
12.8 x 600ah equals 7680wh. Not accounting for any loss , that would run the AC almost 5 hours with no solar.
Course, there will be losses. Let's say the inverter is 90 percent efficient. Your still over 4 hours on battery power alone.
For the solar panels my rough guess is you will get about 2 or 3 kwh in winter to as much as 6 or 7 in summer. So in summer on a sunny day that could charge the battery bank to 100 percent.
I would run a 24 volt system and buy a good 24 volt charger that you can charge the battery on shore power and use the solar to extend your run time when dry camping.
Guessing batteries will start at 100 percent if charged while on shore power.
12.8 x 600ah equals 7680wh. Not accounting for any loss , that would run the AC almost 5 hours with no solar.
Course, there will be losses. Let's say the inverter is 90 percent efficient. Your still over 4 hours on battery power alone.
For the solar panels my rough guess is you will get about 2 or 3 kwh in winter to as much as 6 or 7 in summer. So in summer on a sunny day that could charge the battery bank to 100 percent.
I would run a 24 volt system and buy a good 24 volt charger that you can charge the battery on shore power and use the solar to extend your run time when dry camping.
Yes I have been thinking about 24 volt. I understand the principal. Haven't done the deep dive yet. But batteries, controller and inverter all within 2 to 3 feet. At first glance 24 volt equipment other than wires fussing etc are way more expensive especially lp4 batteries. I know you can put 12 volt in series but then you introduce balancing issues. Without those two hurdles overcome I would prefer 24 volt. Also would need a converter back to 12 volt, another inefficiency. I guess that's why I need the forums help.
CommandoJoe
Solar Enthusiast
Have you considered an inverter AC or minisplit? I have a 12k BTU inverter window unit in my travel trailer that normally pulls between 300-500w and as much as 1200w when it's really hot. The rooftop AC built into the trailer pulls a constant 1300-1500w. I only use it when the window unit can't keep up during the peak of summer during the day.
Since you said you want to run the A/C at night then the solar panels don't matter. It's all on the battery. In my prior trailer I could run the 15k BTU A/C for about three hours off of the batteries (560 Ah) and still have enough juice to run other things in the morning, but that was starting the cool down while the sun was still up when the solar charge controller was taking some of the load.
No, I wouldn't put LiFePO4 BMS-based batteries in series, exactly for the reason you said.
Check the efficiency of your inverter. Mine was a Victron Multiplus 12/3000 which has an efficiency of 93%.
No, I wouldn't put LiFePO4 BMS-based batteries in series, exactly for the reason you said.
Check the efficiency of your inverter. Mine was a Victron Multiplus 12/3000 which has an efficiency of 93%.
Yes, I like that inverter. You know the more I think about it I could beef up the batteries day to 1200 amps, not use so much solar, maybe 800 watts, get an inverter charger. That would give me plenty of power on those single night stays. How much charger would I need to fill 1000 amps in a 24 hour period?
The common theme on this forum is that you can spend a lot of money adding capacity, or you can spend less money reducing the load. Finding a way to achieve your cooling goal that is more efficient but still effective is the way to start.
New rooftop A/C units have come out recently that are a lot more efficient. Mini-splits are super efficient but the install of most of those units in an RV just isn't practical.
On the topic of solar panels, installing 12 100 watt solar panels sounds tedious. Look at 400+ watt residential panels that you can purchase locally. Fewer panels = quicker/easier install. I'm running four 420 watt panels on the roof of my RV, with plans to add a couple more.
Once you get to a certain threshold of PV watts, it makes sense to switch from a 12 volt system to 24 or 48 volt. The solar charge controllers can handle more PV watts at higher system voltages. Don't put LiFePO4 batteries in series. If you want a 24 volt system then get a 24 volt battery.
New rooftop A/C units have come out recently that are a lot more efficient. Mini-splits are super efficient but the install of most of those units in an RV just isn't practical.
On the topic of solar panels, installing 12 100 watt solar panels sounds tedious. Look at 400+ watt residential panels that you can purchase locally. Fewer panels = quicker/easier install. I'm running four 420 watt panels on the roof of my RV, with plans to add a couple more.
Once you get to a certain threshold of PV watts, it makes sense to switch from a 12 volt system to 24 or 48 volt. The solar charge controllers can handle more PV watts at higher system voltages. Don't put LiFePO4 batteries in series. If you want a 24 volt system then get a 24 volt battery.
From PV or shore power?
My Victron Multiplus 12/3000 would put 100 amps into my battery bank. In the context of your question, that's ~10 hours to charge a 1000 Ah battery bank from 0% state of charge.
You won't get 10 hours of sunshine, so 1200 watts of PV mounted flat on the roof isn't going to charge the same battery bank in one day. Maybe two days to charge, at best, probably pushing it to three days.
SouthernSolar
Solar Enthusiast
Nothing wrong with putting battery in series. I haven't had a problem. I bought Victron batrery balancer but return it. The shunt monitors the mid point voltage and if it gets out of balance, very rare, I just put a load across the battery with higher voltage.
As far as I know, there's only one 110v rooftop RV A/C with highish efficiency out there (The TURBRO 13,500BTU inverter one) and unfortunately, the price has hiked up considerably from where it was a couple months ago.
(I guess there's also the furion chill cube, but no heating and from what I understand its efficiency isn't that great, so...)
CommandoJoe
Solar Enthusiast
ECO-COOL Black Ducted
Unprecedented 2 year Replacement Warranty Why Choose us ECO-COOL is built for any extreme climate condition SLEEK AERODYNAMIC DESIGN ECO-COOL is everything you want in an AC system when making that buying decision for your new RV, or if you’re replacing a poorly performing unit. Its...
ecocool.premierproducts.net
scrubjaysnest
Solar Enthusiast
I get 2 1/2 hours on 400 aH bank with temp upper 80's to 100 with 15 btu unit. That's during the day with help from the solar.
Expert Power 3k watt inverter.
Expert Power 3k watt inverter.
That's the GREE unit I think -- fixed EER of ~8. No variable speed compressor, so it's on or off. The Turbro 13,500 can scale back to ~7500BTU, consuming only around 400w, so achieving an EER of ~18 on it's lowest setting and ~11.5 on its highest -- approaching the efficiency you'll get from a mni-split.ECO-COOL Black Ducted
Unprecedented 2 year Replacement Warranty Why Choose us ECO-COOL is built for any extreme climate condition SLEEK AERODYNAMIC DESIGN ECO-COOL is everything you want in an AC system when making that buying decision for your new RV, or if you’re replacing a poorly performing unit. Its...
CommandoJoe
Solar Enthusiast
Downside is it's not ducted.
Yeah, no ducted option for it, though there's a video of a guy doing a ducted install with a 3d printed adapter. For ducted A/C with variable speed compressor there's the Furrion, but no heat, and I don't believe it scales back as far as the Turbro. No perfect option for ducted yet.
CommandoJoe
Solar Enthusiast
Hmm, still no perfect all-around solution. I would like something with heat - since I'm stationary I may just do a minisplit with a ceiling cassette replacing the rooftop unit. Until then my inverter window unit has been working pretty good - for cooling at least.
I went back and forth between doing a mini-split or not, then the Turbro came out, so ordered it (on back-order.) Mini-split install would be a lot cheaper, but would take a lot more time/hacks to install. Hard to get an exact read on how much more efficient a mini-split would be but most of the 12k BTU 110v mini-splits I looked at had around an 11 to 13 EER mark, give or take (The SEER and SEER2 ratings are kind of meaningless for RVs.) Double the cost for the Turbro, and a bit louder, but probably a 5th the labor/time to install, and just a cleaner result in the end.
Here's that guy hacking the Turbro into his ducted system and giving it a full review:
(Edit: I also blame this guy for the back-order and price hike!)
Last edited:
Similar threads
