contemplating new solar setup

[unicutie]

Hello everyone.

So I currently have 200W of solar on my van's roof. It's been awesome and no major complaints for my needs, until now. I also have recently acquired a classy honda generator to power an ac unit now that summer is approaching. But there's things that I really don't like about this setup anymore. And I haven't run the generator even ten hours total yet.

The generator was over 1000 bucks. It's not *loud* but, still. It's a small engine. It sounds like a quiet lawn mower. It's not a problem when I'm parked next to an intersection but I can't run it at night and it's not stealthy at all. A gallon of gas runs the ac compressor for just 5 hours. Gasoline stinks and is dangerous to haul around in a jug. And now it's increasingly expensive.

Then, I'm having trouble with my batteries not charging as I have to park in the shade to keep the temps down.

So I'm thinking, what if instead of this mish-mash of thrown together systems, I just go all out on solar so that I can park in full sun and still keep the inside cool... plus the batteries charged ...

**

So I'm thinking about selling parts of my current setup and upgrading to a maximum-possible solar array, one that is capable of powering my 6kbtu window unit. Maybe even ditch the propane tank for an electric hot plate. Not gonna lie, a recent video of bob's plus a question from a stranger about my panels+window a/c has got me seriously considering this option. I am considering selling the brand new little red generator and the 2x100W panels I have now, as well as the 20amp mppt controller, and getting 3 or 4 residential panels, 2 more golf cart batteries, and a beefy charge controller to go full-solar. 

I'm brainstorming, and since I don't have a plan at the moment, this post is a bit pointless. But I guess I'm looking for ideas. I'm not even sure how/if I could even fit all that solar up there. But I think it's just barely wide enough. I know it would be long enough. I would have to build a mounting system up there that's tall enough to clear the fantastic vent with the cover removed. My van roof is at least 13ft long, i have the extended van. I'm not sure the width of the roof, but from wall to wall, the inside is around 6 feet or a little less. Residential solar panels are 65"x39". Seems that most are 270W, so I would need 4 of them to clear 1000W. I've seen more expensive 300W panels in that size as well.

I guess this is a request for comment, and a vent. If I move forward with this idea I will use this thread.

 

[DLTooley]

Ya gotta do the math. I did a quick google and folks are claiming 600 watts plus or minus for a 6k btu. I'd close to double the amount of rated panel needed to run the a/c straight, without battery. 600 Watts should take 50 amps, so you will need one golf cart battery per hour(bought in pairs) running without sun, somewhat reduced for late afternoon when there is still some power coming off the panel. For a system of this size you will definitely want some sort of battery management so you understand what is happening. You should also be willing to turn off the a/c when needed to preserve battery life.

If you can't move to a cooler location getting shore power is also an option. As is a swamp cooler, if you are in the dryer West.

 

[John61CT]

Do **not** start expanding your daily **usage** of electrickery until you are happy with the ways you are producing **more** than you are using now.

Anything involving heat requires a **lot** of energy, pretty wasteful in a solar setup.

A mix of different ways to do things gives flexibility and resilience.

Your current goal should be to get your bank to 100% Full at least a few times per week. You need to know how to measure that.

Lowering consumption is one approach.

A genny used the right way in the morning can help if your panels aren't enough.

Adding panels until your roof is full would be the next step, reducing genny usage to just bad solar conditions.

Or then starting to add more portable panels.

 

[tx2sturgis]

Drive North.

Keep doing that until the days are mild and the nights are cool.

It works. 

 

[highdesertranger]

JiminDenver, paging JiminDenver. Jim needs to be in on this conversation. highdesertranger

 

[tx2sturgis]

Yeah, this comes up often.

The general consensus for MOST van-dwellers MOST of the time is that for MOST normal sized vans, there is not enough roof real estate for solar panels to run MOST a/c units for MOST of the day, MOST of the time.

Sure, a few have done it, but they often churn thru money and batteries making it all work.

I personally think that if you pack in a lot of weight (and $cost$) in batteries, and A/C units, and multiple large roof panels, and a couple of portable panels, a high amperage controller, heavy gauge wiring, large inverters, etc, then you have missed the point of van-living 'minimalism'...

Of course it can work with a bigger trailer/RV because then you have the ability to carry lots of batteries and room to mount lots of big panels.

 

[jonyjoe303]

During the winter I added so much foam insulation to my van to keep warm without using a heater which work excellent. Now its summer again and have yet to encounter a day where my 2 amp swampcooler hasnt been able to keep me cool. Many times I just run it on a low setting. Making the rear of my van as airtight as possible helped tremendously, over a typical weekend I might use 4 liters of water and run the swampcooler during the hottest part of the day.

I always park in the sun, the 240 watt panel/20 amp mppt easily handles running the swampcooler all day, with the 100ah lifepo4 I can run all night if I wanted to. 

I'm a big believer that swampcoolers work in more areas then they are recommended for. In some areas you might need a much larger swampcooler but it would still be less power then an AC. But you need massive insulation for it to be effective. I encounter hot humid days here in california, and the swampcooler kept the edge off the heat. In the humid conditions is the only time I ran the swampcooler all night long to stay cool. Its better then just using a regular fan. 

With AC you need a giant battery bank (at least 700 ah of lead acid or 400 ah lifepo4) and almost 1000 watts of solar panels. Hurriedyear website has pictures of his solar setup he uses to power his AC. He has a larger sprinter van. If I needed AC I would stick with the generator, it be more cost effective. In the end even if you could get enough solar, you might still need the generator to top off the batteries from time to time, especially lead acid which don't like to be left discharged for long periods of time.   

I had to use longer L-brackets to install my panel so it would clear one of my roof vents, I had to remove the cover from the vent. Installing panels over vents shouldnt be any problem.

 

[unicutie]

Thanks. Well, let me explain a bit more. I would probably not be contemplating any of this if it was just me. I'd just deal with it. But I'm in north Texas and I have a dog I need to keep cool during the day. At night I will have shore power available.

So my thinking is : I would only really need to provide panels enough to directly run the ac when the sun is out. If i quadruple my solar and only double my batteries, I should have little trouble reaching full charge regularly. If I insulate well, which I am in the process of that, hopefully the compressor wouldn't be running the entire time.

But yes I'm thinking the fit would be tight. That would be a project in itself  though I have no qualms about putting together a contraption. Anything for the pup. I am gonna go measure and see what I'm working with.

 

[tx2sturgis]

The last update from awhile back, I thought you were way over in Flagstaff area...dunno where I got that idea....anyway..

Are you and the dog sitting in the van during the heat of the day? If so, let him outside, they love to lay in the shade under the van, assuming he can fit. 

If you are leaving him unattended while you are out working or whatever, then any single failure of any component in the chain will mean your dog could be baked alive.

 

[unicutie]

we had to come back to texas. And yea I have no where to keep him while I work. we're good in here up to around 85-90 degrees with the vent and fans. Yea I'm very conscious of the fact that this system needs to be reliable, which is why i dished out for the honda genny. I can keep an eye on the van while I work, I work at a pizza shop and i park right out front. I would be very uncomfortable about leaving him truly unattended.

If i sold the generator I could get a good price for it, part of the reason I felt ok about buying it is because I know that honda gensets are highly re-sellable. I could probably sell my 200W mppt stuff as well. You can pick up 1060W of grape solar panels at home depot for $1k. Then I would just need cable, inverter, mounting, charger, and 2 more batteries.

I had a look up there and yea, they would fit although it would be a pretty serious platform on top! They would be almost as long as the entire roof and about an inch wider than it. It would definitely be an interesting look, even less stealth than my van already is, lol. I'd probably run 2 wood rails down the length and bolt the panels to the wood. I guess one advantage would be that the entire roof would be under shade.

and yea when we're in a good situation for it, he loves hanging out underneath the van

 

[wmyers4u]

Two thoughts

1. They make smaller window units. A smaller one will give you more amp flexibility on bad days

2. Something I am considering..... A removable thermal barrier aka insulating curtains midway through the living area so I'm cooling/heating a smaller space when not in use or in times of lower solar charging.

 

[tripper]

3 x 60 cell good house solar panels will get you 900-1000+ watts of solar which is plenty to power a 5K btu AC, it will probably power a 6k btu AC also.
These are about 67 inches by 40 inches each. Put together on a roof would be about 5 1/2 feet by 10 feet long, using L brackets you can space them up high enough to clear your vents without looking like it is too high. A 1000 watt or bigger inverter will power up a 5k AC.
Expect 350-450 watts of power being used by the ac while the compressor is running.
This system would only be useable during the main daylight hours.
Not reasonable to use at night unless you have a huge amount of battery storage, say 1 x 100 AH deep cycle battery (lead acid) per non sunlight hour.

Cost to build between $1600-$3000 depending on which panels, controller, etc.

The only way to avoid the huge shipping cost on house panels is to pick them up yourself. Local residential installers often have surplus house panels, call around and see if they will sell you any locally.

BTW there are two common sizes of house panels available, 72 cell and 60 cell. The 72 cell ones are too long for a van roof (almost 7 feet, ~80 inches) going crosswise.
I am going to post a detailed listing of everything needed to run a 5k AC during daylight hours here in a week or two.

For daylight hour use any good deep cycle battery will work as you are running off the solar not the battery.

LG has very high efficiency 72 cell 405 watt panels and 60 cell 365 watt panels if you can find source them. Beware that a lot of the inexpensive house panels you see for sale are low efficiency older 72 cell panels

I know the system works as I have it and use it often. I use 3 x 305 watt panels to run the 1000 watt inverter and 5k AC. If there is sunlight I can run it indefinitely.

 

[DannyB1954]

Hello everyone.





Then, I'm having trouble with my batteries not charging as I have to park in the shade to keep the temps down.

So I'm thinking, what if instead of this mish-mash of thrown together systems, I just go all out on solar so that I can park in full sun and still keep the inside cool... plus the batteries charged ...



I guess this is a request for comment, and a vent. If I move forward with this idea I will use this thread.

I just installed a solar system that runs my 6,000 BTU window air conditioner. I used the longer solar panels as they utilize the roof space more efficiently. At night though it may be impossible as you would need so many batteries that you would probably overload your van. I used six 160 watt Renogy panels for a total of 960 watts. You can see my set up here        There are more efficient panels made by a Chinese company but if you ever need support, good luck. Grape solar also has panels that put out 20 Watts per panel more but they are about $70 more per panel. If you don't mind going wider than the vehicle by a bit, Solar panels for houses can be made to fit.
You will need more solar than mathematics would indicate. The A/C may only take 420 watts to run, but the solar panels will never put out their rated output laying flat on the roof, (they need to be 90 degrees to the sun to get max). There will also be intermittent cloud cover so the batteries will drain when the sun is behind a cloud and the solar needs to be large enough to not only run the A/C but also recharge the batteries, (from being drained due to cloud cover). The panels and controller set me back about $1,200 and then figure another $200 for brackets and hardware.
For me it was worth it as I live where it gets hot, (Southern Nevada), and I like keeping my dog cool while I am shopping.

 

[unicutie]

THanks for your input. Yea i have thought more about this, If I reorient the 200w of panels I already have, I can get a rack and put three regular house panels to get an extra 750-800w. I've seen the 300w ones, they're a good bit more expensive. I haven't considered the renogy 160 panels actually though I was looking at the bigger ones of theirs. I would get a second battery bank and wire it at 24v. I would probably use 2 charge controllers instead of one big one. I would set it up so I could switch the original panels from the 12v bank I already have to the 24v one and pick which one to charge.

I will also need to add a lot of insulation, which I'm going to do first since I can't really afford a $2k solar project right now! I'm also looking into building a battery bank from li-ion cells instead of more golf cart batteries.. Not sure yet! Either way I like the idea of having a good sized solar array. Maybe by the time summer is over and I don't need a/c anymore, I'll be able to afford it

 

[DannyB1954]

THanks for your input. Yea i have thought more about this, If I reorient the 200w of panels I already have, I can get a rack and put three regular house panels to get an extra 750-800w. I've seen the 300w ones, they're a good bit more expensive. I haven't considered the renogy 160 panels actually though I was looking at the bigger ones of theirs. I would get a second battery bank and wire it at 24v. I would probably use 2 charge controllers instead of one big one. I would set it up so I could switch the original panels from the 12v bank I already have to the 24v one and pick which one to charge.

On the solar panels I went with what would fit my roof the best without empty space. On my van, house panels would be too long, and with 100 watt panels I could fit two next to each other but not have enough room left over for a third. That partial empty space would be useless. So choose whatever panels that will fill your roof completely from side to side.
With a MPPT controller you can wire the panels in series for 24 volts while still keeping a 12 volt battery system. The controller will change the 24 to 12 for battery charging. The advantage to doing this is the panels will produce more usable power on cloudy days or during mornings and evenings. The disadvantage is if one of the panels gets put into the shade, the other panel that is mated to it will also be reduced in output. Kind of like a chain is as strong as it's weakest link.

 

[unicutie]

i have experience with the chain thing, one little branch cast a shadow on a part of your panel and the whole thing takes a hit. My two panels are wired in series.

I might go 12v if I do a lithium bank. If I do a lead acid one I will do 24v because of discharge rate. Also I think another reason I had for 24v was that charge controllers can handle more panels at higher voltage and i was looking at maxing them out.

 

[DannyB1954]

I just wired my panels for 24 volt to charge a 12 volt set of batteries and my charge controller , (which is supposed to be MPPT), did not charge the batteries well. I re wired panels for 12 volt and the controller works just fine. It is quite hot here, so maybe the heat generated from changing the 40 volts solar to 14 volts created too much heat for the controller.

 

[ericlp]

Here is the nitty gritty... The real answer is "NO!"

1) 500 Watts @ 120 Volts = about 4.1 Amps.
2) 500 Watts @ 12 Volts = Around 41.6 Amps

I hope you now see where this going? Downhill pretty damn fast. So even with 200Amp Hour Battery with only a usable 30~40 % capacity (drain it down much further than that and you will KILL your battery life in a hurry(don't DO THAT!!)).

So, a fully charged 200Amp hour battery, draining at 30% (max level), about 60 amps, witch means you'd probably only be able to run your AC off of a FULLY charged 200 Amp hour battery for AC alone for about an hour. So, if you wanted to run your fridge, charge a laptop, lights, cellphone, etc...etc...forget it, that battery is hosed till it can be fully charged.

Now let's say you actually got 500 watts of solar panels on your roof of your van (highly unlikely). You would only get a full 500 watts if the panels were extremely clean, (yes you went up there and cleaned them daily)... And you would only get that FULL 500 watts for about 2~3 hours a day. Remember that is a huge difference between 500watts of solar from the panels at 12 or 24 volt solar panels DC vs.. 500 watts grid power at 120Volts. See above chart... Just because you are getting 500 watts does not mean you are running 500 watts @ 120 Volts.. nope nope and nope.

Now, you really don't get that full charge since, converting the power from the panels thought the charge controller you'll lose about 5% of that, and to STORE the Energy to the batter is another 5% loss. Then to convert that power to 12volts DC to 120 Volts AC, is another 10% loss... plus probably another 5% loss just going through all the mazes of wire coming from the roof, all the way to the AC. So..... You can really see how poorly inefficient this is... Reality is you'll need to pump in around 800+ watts to run a 500BTU AC off of SOLAR alone!

Now if they made a 12 Volt AC, and you had lithium ion... pretty much you would only lose out about maybe 5% since you wouldn't need the inverter and Lithium is very effient about losing any power... And DC AC's are very expensive! Not just something you can pick up at HomeDepot.

But the Advantage of Lithium is you can drain that battery down to almost 10%. so for a 200amp hour lithium battery you would be able to run the AC about 2.5 times longer...and lithium will charge faster to boot! And... if that weren't enough, Lithium batteries will last 3-4 times as long over a heavy lead acid battery...

The down side? While cheaper than a lead acid battery over the long run, the up front cost is hell of expensive. running around 2K for two 100 amp hour batteries.

 

[ericlp]

(part 2) apparently can't post such a long reply.

So what did we learn from all this? If wanted to run AC in your a 5000 BTU that will only suck down about 430 watts (get the lowest wattage AC you can buy)....

You will need max solar panels on the roof maybe 400 watts, lithium batteries 400amps should do it. and MORE... Like an underhood generator (basically a high amperage output alternator) with a remote start, so the system would basically start the van to run the generator to charge up the batteries when they get low. Kinda like how a toyota prius does it. 400Amp hr battery alone will run you 4K, 1K for solar, and probably 1~2K for underhood generator with remote start (see how roadtrek does it). Probably only need to start the van 3/4 times through the night. So, for about 10 grand, you could have to ability to go anywhere and have AC without starting a stinky generator. Even tho, honda is the BEST! Hopefully your running NON ethanol fuel for that honda. If not you'll be clogging up the carb and cleaning it sooner rather than later. You didn't say what honda you got, but hopefully you got the EU2000 minimum as it will run more effient on that load than the EU1000 and will also lower the sound level.

That is why on a house you have MASSIVE roof space, where you can even tilt the panels to get the most from the sun's energy. But even if you wanted to power your AC at home, one would need minimum about 20 300 watt solar panels... massive battery banks. and that would be to cool down one room and still run the rest of the house ...esp, if you wanted to run AC at night.

Cheers!

 

[DannyB1954]

A Ryobi 900 watt propane generator, (700 watts continuous), runs my 5,000 BTU window air conditioner just fine. It hooks up to a 20 lb propane bottle and can run for several days. Manufacturer says it will burn 1 lb in 3 hours. Propane engines do not stink. They often use propane powered forklifts in warehouses. Gas engines are not allowed.

So in theory anyway the generator will run for about 60 hours on 20 lb, ( 3 hours per lb). Propane is sold by the gallon. Propane weighs 4.2 lbs per gallon. 5 gallons of propane weighs 21 lbs. Prices vary for propane. At $3.50 a gallon that would cost about 30 cents an hour to run the generator, ($3.50 times 5 is $17.50 That divided by 60 is $0.29 an hour).

My solar system can run the air conditioner from about 10 am to about 5 pm here in Southern Nevada. The cost of the parts to do my solar system is under $1,500. The generator was about $350 I think. I don't like batteries as they take up space and weight. I am using two 100 amp hour batteries, ($220). That is what I figure I need to get me through the night to run lights and 12 volt compressor refrigerator. Here in the Southwest desert the night temps cool so I don't need the AC at night. The most I think I run the generator is maybe up to 3 hours a day in the summer heat. So about a dollar a day to stay comfortable as I like. This system also allows me to have a microwave oven and a George foreman type of grill.