I want to run a solar setup to run a A/C unit

hozer · September 2014

I want to run a solar setup to run a Window A/C unit in my RV via Solar. The unit is a small 5,000 BTU 500 watt A/C.

What will I need to run a 500 Watt A/C .................

IE: how many panels, How many batteries, DO I need a solar charge controller and a MPPT inverter

Thanks

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

This is a hard task, how many hours do you want to run the a/c for?

I managed to run a window a/c for about 4-5 hours at night on a 1000 watt array along with some other loads and 4 golf cart batteries. Once I increased the array I was able to run it more during the day as an opportunity load, not relying on the battery for energy much, and since it cycled on and off the battery bank stayed mostly topped off. It will be harder for you, since an camper tends not to be very well insulated.

Your location will also be a factor, here in Missouri we have our heat with the sun typically. Running 4-5 hours at night in a well insulated cabin, along with a fridge and other minor loads. I was drawing down the battery 30-50%. If I wanted longer run times I shut down the fridge, giving me maybe a couple hours longer run time.

When I say run time, an a/c is thermostatically controlled, with a well insulated cabin(6" walls) in the shade I might run the first hour continuously, but maybe 30-40% once the mass was cooled down.

hozer · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

This is a hard task, how many hours do you want to run the a/c for?

I managed to run a window a/c for about 4-5 hours at night on a 1000 watt array along with some other loads and 4 golf cart batteries. Once I increased the array I was able to run it more during the day as an opportunity load, not relying on the battery for energy much, and since it cycled on and off the battery bank stayed mostly topped off. It will be harder for you, since an camper tends not to be very well insulated.

So what you would think it would cost me to make a solar setup just to run the 500 watt A/C unit? I will be running the unit approx 4 to 5 hours a day and 1 hour on and one hour off on a timer.

Cariboocoot · September 2014

Re: I want to run a solar setup to run a A/C unit

Welcome to the forum.

No you don't.

Providing enough power to run a typical 500 Watt A/C is a big and expensive project. First of all the start-up surge is nasty on these things, requiring a sizable inverter just for that. We're talking 30 Amps @ 120 VAC, only for a moment but its demand must be met. Typically an RV system will be 12 Volts and if you do the simple math you see how much DC current that is, never mind conversion losses.

Second there's the run-time variation. Anything that cycles on/off with a thermostat has a somewhat unpredictable Watt hour consumption. If it is on 1/3 of the day that's 500 Watts * 8 hours or 4 kW hours which is a large amount of power. Too large to be practically stored in a 12 Volt battery bank. You're looking at nearly 700 Amp hours of battery at least.

Third if you were to try and recharge those batteries purely from solar you'd need a much larger RV because you'd need room for 1000 Watts of PV. In short it's not simple, easy, or cheap to power one of those things.

Some of the forum members have RV's with A/C and may have some suggestions as to a better way to go about this. The first thing will probably be advice on using a different A/C unit such as a mini-split.

If you search around the forum awhile you'll find threads and posts about these, as well as standard A/C units, and how to get them to work from RE.

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

Where are you located?

I'd think a 1500 watt array and 2 strings of 4 golf cart batteries would be minimal, unless you can park in the shade and are very well insulated.

Something like;

1500watt array around $1500, Charge controller for a 24v system MPPT charge controller Morningstar MPPT 45 with a little clipping $400, * sams club or Costco batteries, $800, Inverter ExelTech XP1100 $600, wiring, racking, breaker and combiner boxes, perhaps $600-$1000 more...

hozer · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

Where are you located?

I'd think a 1500 watt array and 2 strings of 4 golf cart batteries would be minimal, unless you can park in the shade and are very well insulated.

Something like: I live in western Colorado we get about 290+ days of sunny weather

1500watt array around $1500, Charge controller for a 24v system MPPT charge controller Morningstar MPPT 45 with a little clipping $400, * sams club or Costco batteries, $800, Inverter ExelTech XP1100 $600, wiring, racking, breaker and combiner boxes, perhaps $600-$1000 more...

So what your saying it not worth the money to have a solar setup just to run a 500 Watt A/C unit and maybe some other devices correct?

This what I was thinking of buying for a 24 volt system........

6 - LG 305 watt solar panels ( 305 watt output each total 1830 watts ) ( around 75 amps output )
Magnum 5000 watt 24 volt inverter
Schneider (Xantrex) XW-MPPT-60-150V Charge Controller
4 - 6 volt 480ah Royal AGM batteries.
( Plus 3 - 30 amp fuse boxes and a junction box for the solar panels

Cost around $6500 bux

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

Cariboocoot wrote: »

No you don't.

It is a pretty good sized system, if the RV is parked and in inplace and no grid is available the system I quoted would work, I think. But it is too large to mount on an RV.

A system of a plug and play reliable Honda generator, I think some A/Cs have run off Honda's EU1000? so $1200 and the balance saved over the above system would buy a lot of gas.

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

hozer wrote: »

So what your saying it not worth the money to have a solar setup just to run a 500 Watt A/C unit correct?

This what I was thinking of buying!

6 - LG 305 watt solar panels ( 305 watt output each total 1830 watts ) ( around 75 amps output )
Magnum 5000 watt 24 volt inverter
Schneider (Xantrex) XW-MPPT-60-150V Charge Controller
4 - 6 volt 480ah Royal AGM batteries.
( Plus 3 - 30 amp fuse boxes and a junction box for the solar panels

If I could place a nice camper on land I owned, isolated with beautiful scenery off in the woods, I would gladly do a solar system. I personally don't care for generators and don't own one.

Not sure what you need a 5000 watt generator for, I'm running a household off 1800 watt and had planned on only a 3500 watt for the house. I can start my window A/C off the 1800 with no problem, It's a little small if I want to run the toaster over with anything else, or if the microwave and the fridge are running and the a/c kicks in it's kick out the inverter. ...but I have a much larger system and loads than you should likely want to run in a camper. You don't intend to heat with it?

I'm not familiar with the Royal batteries, I thing flooded are the best bang for the buck and have no experience with AGMs.

It's all good equipment, I think I would prefer a Midnite Classic Charge Controller, Outback inverters, though Magnum have a pretty good rep. Not sure what your suggesting by the 3-30amp fuse boxes? and perhaps your equating a combiner box with a junction box? Junction boxes usually refer to the box attached to the back of the solar panel.

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

If I could place a nice camper on land I owned, isolated with beautiful scenery off in the woods, I would gladly do a solar system. I personally don't care for generators and don't own one.

I should say with no grid available, I have grid available here, but already had a large battery and other equipment which made off grid more cost effective.

hozer · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

If I could place a nice camper on land I owned, isolated with beautiful scenery off in the woods, I would gladly do a solar system. I personally don't care for generators and don't own one.

Not sure what you need a 5000 watt generator for, I'm running a household off 1800 watt and had planned on only a 3500 watt for the house. I can start my window A/C off the 1800 with no problem, It's a little small if I want to run the toaster over with anything else, or if the microwave and the fridge are running and the a/c kicks in it's kick out the inverter. ...but I have a much larger system and loads than you should likely want to run in a camper. You don't intend to heat with it?

I'm not familiar with the Royal batteries, I thing flooded are the best bang for the buck and have no experience with AGMs.

It's all good equipment, I think I would prefer a Midnite Classic Charge Controller, Outback inverters, though Magnum have a pretty good rep. Not sure what your suggesting by the 3-30amp fuse boxes? and perhaps your equating a combiner box with a junction box? Junction boxes usually refer to the box attached to the back of the solar panel.

I live in my 40' 5Th Wheel. Yes I will use heat. Sorry I ment Rolls Agm Batteries: Linky: http://www.rolls-battery.com/pdf/S6-460AGM.pdf

Now as far as heating I was hoping to run a 1200 watt heater for a few hours a day. Not all day long.

Here is what I was talking about the fuses setup:

Solar Setup:

1. Solar Panel Wires To Junction Box ( On Roof )
2. From Junction Box to 30 Amp Fuse Box.
3. From 30 Amp Fuse Box To Solar Controller.
4. From Solar Controller To 30 Amp Fuse Box.
5. From 30 Amp Fuse Box To Battery.
6. From Battery to 30 Amp Fuse Box.
7. From 30 Amp Fuse Box To Inverter.
8. From Inverter To Receptacle.

DONE!!!!

Reed · September 2014

Re: I want to run a solar setup to run a A/C unit

Have posted before that we have 1420 W of panels on our 5th wheel. We do have 9 kW-hr of LFP and 4.0 kW PSW inverter. We can run a Dometic power hog (1500 W actual) air conditioner for 3.5 hours (have done twice) on solar/battery bank. With full solar (1200 W delivered to controller), we are still drawing 900 to 1000 K from the battery bank. We usually just run it for an hour in late afternoon to cool things down.

You can pack a heck of a lot of solar panels on a 5th wheel (we could pack in another 700 for 2100 W total but that would be overdoing it). Brian Appleby has 1200 W of panels. on his truck camper and trailer (for his BMW motorcycle). Some folks do put X W on top of smaller RV's and some fold ups on the outside. Some folks on The Grey Nomads (Oz land) speak of doing this under "Techie Corner" sub-forum.

You definitely need a controller MPPT (Maximum Power Point Tracking) and inverter. We inadvertently ran the a/c a couple of times on our old system of 700 W of panel, 2.5 kW PSW inverter, and 4 good sized glass mat batteries. It ran for about 30 minutes - and died! We were at a decrepit RV park in Portland, OR and I had not turned on the power (30 amp switch on the RV park post).

So as Photowhit noted, a 1 kW array should easily handle a 500 W window A/C during daylight hours. You just need the battery bank and inverter to get it going. I would think that you could only run it during daylight hours with strong solar insolation. 12 V fans work well once it gets dark.

We are "Goldilockers" as in "not to hot and not to cold, just right!" and go north/higher in elevation in summer and south in winter (Yucatan). I do not know what you do if you are trying to "survive
" in southern US in summer with 90 degree temperatures and 90% humidity.

We are looking into obtaining a small a/c unit such as you have or one of the split level systems to keep things moderate.

Reed and Elaine

hozer · September 2014

Re: I want to run a solar setup to run a A/C unit

Thanks for the reply bud

Since you are running 1200 watts to the controller to run your A/C unit I should have no problem running the solar system running the following hardware:

6 - LG 305 watt solar panels ( 305 watt output each total 1830 watts ) ( around 75 amps output )
Magnum 5000 watt 24 volt inverter
Schneider (Xantrex) XW-MPPT-60-150V Charge Controller
4 - 6 volt 480ah Rolls AGM batteries.
( Plus 3 - 30 amp fuse boxes and a junction box for the solar panels

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

hozer wrote: »

Thanks for the reply bud

Since you are running 1200 watts to the controller to run your A/C unit I should have no problem running the solar system running the following hardware:

6 - LG 305 watt solar panels ( 305 watt output each total 1830 watts ) ( around 75 amps output )
Magnum 5000 watt 24 volt inverter
Schneider (Xantrex) XW-MPPT-60-150V Charge Controller
4 - 6 volt 480ah Rolls AGM batteries.
( Plus 3 - 30 amp fuse boxes and a junction box for the solar panels

Sorry, I think you have a poor understanding of solar and equipment and should run a generator. Magnum doesn't make a 5000 watt inverter, Rolls doesn't make a 480ah AGM battery, a 30 amp fuse doesn't solve all (or likely any in this case) fusing problems.

waynefromnscanada · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

Sorry, I think you have a poor understanding of solar and equipment and should run a generator.

I have to agree. Yes, you can spend the money and set up your dream system, but as it now stands, the dream will very quickly become an expensive and disappointing nightmare.

hozer · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

Sorry, I think you have a poor understanding of solar and equipment and should run a generator. Magnum doesn't make a 5000 watt inverter, Rolls doesn't make a 480ah AGM battery, a 30 amp fuse doesn't solve all (or likely any in this case) fusing problems.

Ok Sorry my typing is not the best

#1 Magnum DOES make a 4000 watt inverter

linky: http://invertersupply.com/index.php?main_page=product_info&products_id=292&cPath=0_104&gclid=Cj0KEQjw7vmgBRDdnLPZp7aBlroBEiQA7_NmVzINeEuqZN_VYZPL6IUObtdtfMORKV0E9u22ifj3kuwaAiUL8P8HAQ

#2 Rolls DOES make a 460ah AGM battery

Linky: http://www.rolls-battery.com/pdf/S6-460AGM.pdf

Have a nice day!

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

hozer wrote: »

#1 Magnum DOES make a 4000 watt inverter

linky: http://invertersupply.com/index.php?main_page=product_info&products_id=292&cPath=0_104&gclid=Cj0KEQjw7vmgBRDdnLPZp7aBlroBEiQA7_NmVzINeEuqZN_VYZPL6IUObtdtfMORKV0E9u22ifj3kuwaAiUL8P8HAQ

I was a bit frustrated last night, Sorry for being so sharp. We all started with little knowledge about solar, so I'll try to walk you through the basic's in a bit. This is a large inverter, and unless you intend to run multiple heavy loads, likely more than you will need. If you need to be able to 'flip a switch' and not think about the energy use, I think solar will be frustrating for you.

hozer wrote: »

#2 Rolls DOES make a 460ah AGM battery

Linky: http://www.rolls-battery.com/pdf/S6-460AGM.pdf

While this is 'called' a 460 amp battery, if you are comparing it to other batteries, consider it a 415 amp hour battery. Several battery manufacturers use a 100 hr discharge rate, for some batteries. But the standard is a 20 hour discharge rate.

Solar energy systems, take energy from the sun and store it. Since it can't store sun light there are many losses involved in the storage of energy.

Solar panels are rated for ideal conditions, they typically produce 75-80% of their rated value on good sunny days with the sun within 15 degrees of being directly in front of the panels. Will you be able to angle your solar panels? Will this be a fixed location or are you planning on traveling?

There are some sites that will help you determine how many charging hours you can expect during a day. Here is one. Please note that Off grid systems MUST HAVE WASTE! to fully charge your batteries, their must be more energy than the batteries can store for proper battery health (the LiFePo battery chemistry, people may get away with less, but suspect they would mostly agree with this statement)

Solar panels have fusing rating the ones you suggested have a series fuse rating of 15amps, this is the fuse or DC rated breaker you would need in your combiner box, where the panels are combined for a wire run to the charge controller. Typically you would have a fuse or breaker ahead of the controller for convenience rated for the combined amperage of the panels, 2 strings may require a 25-30 amp breaker. The charge controller takes the power(watts) and controls the voltage presented to the batteries. In a MPPT type charge controller it also converts any voltage above the needed voltage into more current. The combined wattage of 6 panels would be limited in output through the charge controller to 60 amps, they are capable of a bit more on very good days. so the wiring and fuse or breaker going to the batteries should be appropriate. The will be some losses at the charge controller and through the wiring.

Lead acid batteries require a voltage higher than it's resting voltage to charge so there are losses there.

From the battery to the inverter, you will need appropriate wiring and breakers for the inverter, a 4000 watt 24 volt inverter will be in the neighborhood of 175 amps. Inverters run 85-93% efficient so more losses there.

Complete losses running through an off grid system start to finish run around 50%. So if you go to the link I provided, you can get a clue as to what available energy you will have, Plug in 50% for losses, if your mounting your panels flat on your roof, plug in 0 for angle, this For my location central Missouri, 1.5 KW array flat on a roof will provide about 1.5Kws of energy in Dec, Jan and Feb. Might run your heater an hour a day without additional loads (this goes back to the battery rating) at 1200 watts you will draw 10 amps ac and with the inverters losses 55 amps at 24 volts or 1.32 Kw per hour.

Having your panels angled toward the sun and having obstruction free southern exposure will increase the available power. If your camping this isn't often available, If your in a fixed location, you might be able to do this.

Knowing more about where your system will be located will help creating a functional system for you.

Mountain Don · September 2014

Re: I want to run a solar setup to run a A/C unit

Here's a link to a guy who has converted a cargo trailer to a travel trailer. Sort of... no windows. A whole bunch of PV panels. Used to have some FLA and now has a LifePo4 battery. I am not recommending anyone take what he has / is doing as the right way, but maybe it is food for thought.

He has a blog... http://overthetopcargotrailer.blogspot.com/

and a small trailer forum topic... http://www.tnttt.com/viewtopic.php?f=42&t=44951

and seems to have a lot of money to throw at the project

ZoNiE · September 2014

Re: I want to run a solar setup to run a A/C unit

Attachment not found.
There are times you need ac, and times you don't...

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

Cute cartoon, I can't get over people 'camping' in camp grounds, it has zero interest to me. I'll gorilla camp in unmarked/posted unimproved land, and find it quite enjoy able, but to congregate, in a group of people, 'camping' closer together than they live, and seeing sites as a group of cattle, has no appeal to me.

RandomJoe · September 2014

Re: I want to run a solar setup to run a A/C unit

Yeah, I'll take the AC, please. Was out at a state park on a lake with some friends earlier this year, they were in their fifth wheel at the RV campground. Waterfront parking spot, we had our kayaks right on the beach. Paddle out around the lake all morning then come back for lunch. It was *H*O*T* that weekend! We still went out to do stuff, but being able to cool off a bit in their air conditioned RV made it so much nicer. Not to mention trying to sleep at night - I can be fine in warm or even hot conditions all day, but I need to cool down a bit or I won't sleep a wink.

That said, there was a family two spots down who parked their RV, set everything up, then disappeared inside never to be seen for the entire weekend! You're right, there doesn't seem to be any point in doing that, why even leave home?!?

I guess I'm too timid - don't think I could ever camp somewhere I didn't know if I was allowed. Or maybe cynical - I just KNOW I'd be the one who was caught by some angry owner or tough-guy cop! I don't like crowds at all, but I do like a decently run campground. The RV spots in the state parks I've visited with my friends don't seem to bad, they're spread out fairly well, unlike some private parks I've seen where it looks more like a parking lot with just a couple feet between pads. The state park tent sites are a bit worse, they do pack those pretty close together. On a previous trip with my friends I parked my pickup in an RV spot beside theirs and slept in the bed of the truck. Cost more than the tent spots but lots more space between me and the neighbors. (The last trip I mentioned above, though, I shelled out for one of the cabins - luxury!

)

Photowhit · September 2014

Re: I want to run a solar setup to run a A/C unit

I spent 1999 bicycling and gorilla camping, I don't know that I spent a single night in a paid campground, in the Midwest there are still some county run free campgrounds, usually with limited resources, no power or hot water, pit toilets. I stayed in a couple of those for a night each. Since people love their creature comforts and it was in the middle of the week and not at 'destinations' I only had 1 or 2 others there.

Natchez Trace has/had campgrounds just for cyclist and hikers, and at one time the 3 federal campgrounds were free along the park/road. Again during the week and out of season, not to many people...

CDN_VT · September 2014

Re: I want to run a solar setup to run a A/C unit

Photowhit wrote: »

Cute cartoon, I can't get over people 'camping' in camp grounds, it has zero interest to me. I'll gorilla camp in unmarked/posted unimproved land, and find it quite enjoy able, but to congregate, in a group of people, 'camping' closer together than they live, and seeing sites as a group of cattle, has no appeal to me.

WE NEED A LIKE BUTTON !!

So True ! ...

I have been on the Natchez Trace , cool area !

I want to run a solar setup to run a A/C unit

Comments

Categories