Solar setups

[DeanWinchester]

First off, you can write everything I know about them on a BB with a wide tip marker.

I was fool enough to buy the Harbor Freight package. It is absolute, UTTER GARBAGE. Used it twice, burned out the control box twice. Now it's out of warranty. Grrr.

Anyway. I have no idea how to calculate watt/hrs and all that mumbo jumbo. SO, maybe some of you smarter folk can help me out. I would like a solar setup for my camper van. It needs to be able to handle about half a dozen LED lights which is a pittance. That's simple. The only REAL drain is going to be, I need it to run a box fan and a CPAP machine all night. Can a couple of 12v batteries handle this? I'm thinking a 24v system would be much better. Stepping down voltage is easy and always preferable....eerr so I understand. When me and Mrs. are out, it would need to be able to provide light when needed, keep a small box fan blowing on her during hot weather nights and it MUST handle her CPAP machine at night.
This is as much for camping as it is potential "Bad Times"

As I said, I got burned on the Harbor Freight çrap and ain't doing it again. I have a small gas generator that's more than capable but, (1) it's noisy & (2) you have to feed that pig! I like to have it for emergencies but a quiet, easily renewed system is much more what I want.

I know some of you guys have hunting cabins and whatnot. Care to share?

[lancem]

Need to know how many watts the fan and the CPAP machine draw, that info should be on both items. With that we can calculate the power requirement for 8-10 hours of run time and then be able to figure out what you need to get that solar wise.

[DeanWinchester]

The bottom of the CPAP machine says
115V
-1.27A (1.43A Max)
50-60/400Hz


As far as the fan goes, I can buy any kind of fan, but to make her really happy, I'd like to be able to power her Dyson air foil.

120v
60Hz
.55A


Are those the numbers you're talking about?
I don't know what the LED lights pull, I ain't bought 'em yet. BUT, I can hook up several for what ONE incandescent bulb sucks up. If I can just power up these things with a healthy margin I think I can work the lights in easy enough.

[cbrick]

I also suggest a bank of DEEP CYCLE batteries . . . NOT car batteries. One deep cycle battery = fair - Two = better - Four = good - Six = best. This is for the CPAP strictly so you don't run down the batteries in the middle of the night. Remember also that the batteries MUST be fully charged before you leave, do not rely on the solar to bring several low batteries back to a full charge. Solar will/can charge them back up but it is a trickle charge and could take days to do so.

If you have four 90 ampere hour deep cycle batteries that's 360 ampere hours. If your solar puts out 15 amps to the batteries (that's per hour) that's 24 hours of steady charging without using the batteries to fully recharge them. 20 amp solar is still 18 hours to recharge, 30 amp solar is 12 hours to fully recharge but you don't have 12 hours of good direct sunlight so each day your batteries are less charged than the day before . . .

Rick

[cbrick]

To run the 110 volt appliances you'll need an inverter to convert the 12v DC to 110 AC. Doing so works fine but is a heavy draw on the batteries. You can't run the 110 appliances straight off the batteries. Figure out the combined wattage of all 110 appliances and add them together and get an inverter that handles more wattage than that.

The LED's are a minimal draw but they are still a draw on the batteries so . . .

Rick

[DeanWinchester]

Given my budget, it's probably gonna be 12v but I'd sure like to get a 24v inverter.

[lancem]

115*1.43=165 *8 hours=1320W 120*.55=66w *8 hours =528w 1320+528=1848w total over 8 hours. Talking just round figures with a 24V system I would look at one string of 6V 220AH golf cart batteries (4 of them in series for 24V), I would think one good 230-240W panel would be enough to charge them back up if it is connected all day and no load other than batteries, if maybe some other loading or want quicker charging go with 2 panels. In my experience LED lighting draw is so small and is used for such a short duration in the grand schema of things I don't worry about them in the calculations. Of course depending upon your inverter loss, and the type of charge controller you are using you may be able to size the battery bank/solar array differently but this should be a good start.

Depending upon your planned use you may find that feeding the generator may be the cheapest option in the long run as payback on solar, especially small systems that are infrequently used can be long.

BTW I have been living off grid for over 2 years, I have around 700AH of batteries, and 2800W of panels on a 48V system, and sure do enjoy not getting a bill every month :)

[DeanWinchester]

Where does one get, and how do you know which one; a brain box. Something to manage all this. It sure would be cool if I could have my solar set up with a plug on it to allow me to plug 120v ac into it and feed the batteries, be it grid power or a generator.

[lancem]

I use all Outback power equipment, probably way out of the price range you want to be in for just camping but their inverters allow you to also charge back from the grid/generator. I'm not familiar enough with other brands to be able to recommend something.

You are probably looking at around $1000+ by time you are done with this small system,(batteries $90-120 ea, panels $300 each, inverter, charge controller, wiring) you could feed a generator a long time on that, just saying...

[DeanWinchester]

Another thing that confuses me is; a battery ain't a battery. I understand deep cycle but the battery must match the system and just because it's a twelve volt battery don't mean squat. I have access to bus batteries from school buses. I can get two really cheap.
I have one already and I think that's what cooked the cheapo harbor freight system the first time. I needed a smaller battery.

[cbrick]

You could add a regular battery charger to run off shore power or the generator, that's no problem but be sure to get a charger with automatic shut off feature. Some low end chargers don't and if the batteries are over charged you'll smell rotten eggs and get to buy new batteries.

You said a camper van so I would think that leaves out golf cart batteries, they are kinda big and expensive. That would work well but where are ya gonna put it?

The difference in deep cycle batteries and car batteries is the thickness of the plates. A car battery has thinner plates and is better at supplying a surge of power as in a starter motor but because of the thinner plates will run down quicker. The car battery will take a faster recharge without damage than the deep cycle. The deep cycle battery has thicker plates and will supply power over a longer period of time before going dead but isn't nearly as good at surge power. The deep cycle battery also isn't as good as the car battery at taking a fast recharge, they are better off with a slower trickle charge. A fast heavy recharge of a deep cycle battery can blister the plates (because they are thicker) causing flakes to fall off, collect at the bottom the battery and short out the cell.

Rick

[cbrick]

The school bus batteries are the same as regular car batteries only larger for a heavier electric load (lights, bigger starter etc). The same with big rig truck batteries, just bigger but not different.

The school bus batteries weren't the cause of the solar panel failure assuming the panels put out 12v DC, would just take longer to recharge. If they were equipped with any type of inverter that's a whole nother matter.

Rick

[Deliverator]

I'd make sure that the cells can be connected back into your home when the van is parked in the driveway. That way you are getting the benefit of the panels even when you aren't out camping.

[garym1a2]

I would get a 12 volt cpap machine, 12 volt fan and 12 volt leds and skip the invertor.

[GRUMPA]

I live on solar as well, it does get pricey in a real big way. Here's another way to do what you want, not as good as solar but I'm using it right now as a matter of fact as I type. It's a homemade unit, 6.5HP El-Cheapo engine bought from Evilbay, pulley bought from Evilbay. The generator head itself is a reworked car alternator, been wound for 32v DC. When I have it just above an idle it will produce 10amps at 32v which is just over 300wts. I have it wired right into the load controller to govern it so it wont over charge the batteries. The thing I like about it is the gas tank itself holds something like 9/10's of a gallon of gas, that will run that generator for 7 1/2hrs. So far I've used it for just over a year without so much as a hic-up.

Just click this link for a picture...
http://castboolits.gunloads.com/album.php?albumid=934&attachmentid=89372

[Thumbcocker]

I was able to get a 12v power unit for my cpap machine. Check online.

[MtGun44]

Not rocket science, but it is engineering. I designed and built a home solar system that
has been running without significant issues since 1996.
PM if you want some help.

Bill

[MaryB]

A 220 amp hour 24 volt battery bank will need 22amps charge current to make the electrolyte in the batteries mix properly. Recommended charge rate is c/10 where c is the batty capacity in amp hours. I run a 24 volt 928AH battery bank with 2,400 watts of solar feeding it, 80+ amps charge current at peak. Runs my computer, 2 24 inch monitors, all my ham gear and the TV for the entire night and also the freezer most of the time(has automatic low volt shutoff and an alarm to alert me). Add up all the amps used for everything, for 120 volt equipment multiply by 5 for a 24 volt battery bank(times 10 for a 12 volt) to get the amp draw. Add all those together to get your amp draw per hour. Size your battery bank double that them buy panels that fit the c/10 rate. Never ever run batteries below 50% discharge unless you like replacing them often if using golf cart style deep cycle batteries. There are larger batteries made for solar that take more abuse but they are about twice the price per amp hour.

1,200 watts of panels, about a 10x10 foot square

http://i226.photobucket.com/albums/dd248/maryalanab/Solar-panels-complete.jpg

[leadman]

There is a wide selection of solar parts available on E-Bay. Some good, some not. My son and I both bought from the vendor renogysolar and have been happy with the products. They also have a facility in California with people you can speak with on the phone.
I have 2 sets of the Harbor Freight panels and another 100 watt renogysolar panel on my motorhome. These run thru 2 of the HF controllers with no issues. I have 3 group 29 group batteries and can dry camp for over a week with no need to run the generator. This is running the refrigerator on propane with 12v controls, water pump, water heater 12v controls, fans, lights, tv, heater if needed, and using a 12v fillet knife when needed.

Did you check the fuse on the back of the controller? It is under a black cover there. Also make sure the display button on the front is not pushed to turn off the display.

I have installed led lights that I bought off e-bay also in my original fixtures. When I was debating on changing from incandescent to led I did a draw test on 3 of the incandescent lights and it was 5.2 amps IIRC. Four of the new leds was .5 amps.

If you get an inverter to go from 12v to DC 110v AC make sure it does not draw powder when it is turned off. My first one in our old trailer would draw almost an amp when off.
You can also set up a constant duty solenoid from your alternator to the "coach" batteries to charge them when you are driving. You can either hook it up to close when the key is in the run position or install a separate toggle switch to turn it on. An isolator does not pass thru full voltage and will never bring the batteries to full charge.
You will want to check any electrical item you install that runs off the batteries for parasitic draw (draws when off). Most radios and tvs do draw powder when off.

[MaryB]

Morningstar makes good charge controllers, if you can afford it go with MPPT, it will gain you 20% more charge over a PWM controller.

[DeanWinchester]

I think the wife has found a 12v power cord for her particular machine. Be great if so.

[Finster101]

I am not knocking solar but for the use you have in mind you can purchase a new "QUIET" small generator that sips gas and works when the sun is not out. I have a Honda EU2000. You can barely hear it run and it will go 18 to 20 hours on just over a gallon of fuel and not take up any more space than a medium size cooler. I lived off of it for ten days after I lost power in a hurricane and had zero problems. All I'm looking at is how much room a properly sized battery bank will take up in the camper, it will be a lot of space. Then, would you need a separate bank of batteries for the house as well? I also don't think it would be good for them to not be used frequently. Not bashing just throwing out an alternative.

[Petrol & Powder]

Dean- Lot's of good info here, you'll have to sort through it and glean what you need.
MtGun44 is correct, it isn't rocket science but it is engineering. I'll second the advice about deep cycle batteries. The large 6 volt flooded cell type are probably the most bang for your buck but even those are expensive. I don't know how much space/weight you can dedicate to your system, some of the responses in this thread would involve systems that are very heavy/big/expensive.

Solar power systems are made up of three basic parts: Panels, charge controller, batteries. [an inverter is the forth component if you need to convert 12-48 volts DC to 120 volts AC and sometimes that device can be combined with the charge controller]

The panels convert sunlight to DC electricity. Bigger panels = more power but cost more.
The charge controller is the brains of the system and performs a few functions, the most important is the regulation of the battery charging.
The batteries store the power produced by the panels and deliver that power as needed.
If you need 120VAC, an inverter is used to convert DC to AC and step up the voltage. There is some loss in that process. Don't forget to add fuses/breakers to your design.

Finster101 brings up a very valid point. Despite the advances in solar systems, sometimes a generator is still the most pragmatic option for short term, reliable, stand alone powder. Particularly when short term high loads must be met.

Solar has some strong advantages: stand alone power in remote locations, no noise, good for handling long term low power requirements and no need for a supply of expendable fuel.
However, solar has some disadvantages: VERY High initial cost, weather dependent, must be oversized to handle occasional peak demands.

I'm not bashing solar or generators. A little thought and engineering will serve you well.

Good luck !

[Petrol & Powder]

Where does one get, and how do you know which one; a brain box. Something to manage all this. It sure would be cool if I could have my solar set up with a plug on it to allow me to plug 120v ac into it and feed the batteries, be it grid power or a generator.

I'm not endorsing this company, just providing an example: http://www.altestore.com/store/Charge-Controllers/Solar-Charge-Controllers/c892/

[MaryB]

AltEStore has some really bad reviews if you search. www.solarblvd.com (http://www.solarblvd.com) is good for panels, inverter prices are a bit higher than others. 6 volt golf cart batteries run me around $100 each, 4 would make a 232 amp hour 24 volt bank, 2 a 12 volt 232 amp hour. Space wise they aren't super bulky a bank of 4 side by side will fit in a 30"x12"x12" space with room above for cables. Must be a vented area though to prevent hydrogen gas buildup and a possible explosion.

Vented battery box that has a PVC vet to outside, I was running 12 volts at the time, switched to 24 for better efficiency and ability to use smaller copper interconnects

http://i226.photobucket.com/albums/dd248/maryalanab/batterybox.jpg