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-   -   Airstream factory installed 80 watt solar system (http://www.airforums.com/forums/f295/airstream-factory-installed-80-watt-solar-system-180474.html)

dirksauer 04-20-2018 07:37 AM

Airstream factory installed 80 watt solar system
 
I have a question regarding my factory installed 80 watt solar system. It is showing it charges about 1.2 amp in full sun. Is this to low or is the system working normal???

Crambi 11-04-2018 09:00 PM

I have the same system and will usually see 3.7 amps in full sun. Volt x amps = Watts. Have you cleaned your panel? Dirt will reduce output.

Acheron2010 11-04-2018 09:36 PM

Not to hijack the thread, but I'd be interested in others experience boondocking with the stock 80 watt system. Has it met your needs for lights/furnace/whatever overnight or several nights?

wulfraat 11-04-2018 10:14 PM

80watts is only enough to keep the batteries topped up while in storage, generally speaking . You’ll need more if you want to put energy back into the batteries after an evening of using the furnace, etc...

My first boondocking setup was 300watts. It did ok for my two group 27 lifelines, but after a few years I wanted more output on cloudy days so I moved to 480 watts.

After several years again I changed trailers and now running a big lithium battery bank with 800watts of solar. The panels can generate up to 55amps during the peak hours. I have full residential power without ever having to be plugged in.

All depends what your needs / wants are for boondocking.

pastorwug 11-29-2018 03:43 PM

Quote:

Originally Posted by wulfraat (Post 2176160)
80watts is only enough to keep the batteries topped up while in storage, generally speaking . You’ll need more if you want to put energy back into the batteries after an evening of using the furnace, etc...

My first boondocking setup was 300watts. It did ok for my two group 27 lifelines, but after a few years I wanted more output on cloudy days so I moved to 480 watts.

After several years again I changed trailers and now running a big lithium battery bank with 800watts of solar. The panels can generate up to 55amps during the peak hours. I have full residential power without ever having to be plugged in.

All depends what your needs / wants are for boondocking.

Where did you purchase your 300 watt system?

GMFL 11-29-2018 04:07 PM

Quote:

Originally Posted by pastorwug (Post 2184860)
Where did you purchase your 300 watt system?

Am solar.
https://amsolar.com/

uncle_bob 11-29-2018 04:44 PM

Hi

If you are after furnace + lights + fridge, you are going to use a lot of amp hours.

(Yes there is some guessing here)

Furnace 6A for 10 hours = 60AH
Fridge 1A for 24 hours = 24 AH
Idle drain on the trailer 1A for 24 hours = 24 AH
Lights, water pump, fans ???? guess another 20AH

That's 128AH over 24 hours. Maybe you will get down to half that ... maybe.

Assuming it's winter time, 60% of max output is probably all you are going to hit. The sun is lower in the sky. For each 100W panel you have, 60W x 6 hours = 360WH may be all you get. If that is at a 13V charge voltage, you get 20 AH. To hit the "maybe" low number, you would need a 300W setup. To hit the "more likely" number you are up at 600W. (yes, there's some shortcuts in the math above).

Now, let's say it's cloudy for a day and you get zip. You need 128AH usable battery to keep things running. Your batteries are at 70% capacity due to the cold. You need about 400AH of lead acid's to keep up. Indeed if you get sun at noon and want heat the next morning .... that's going to add to the battery requirement.

After that day of clouds, you now need 2X the solar to keep up with the load *and* charge the batteries.

Simple answer - don't depend on solar in the winter.

Bob

AirMiles 11-29-2018 06:27 PM

Bob is correct that winter solar production will be about 75% less than summer solar production. Bob also provided very reasonable estimates of the number of amps that may be needed in the winter. But I believe Bob was too pessimistic about the effectiveness of solar panels in winter months.

Here is a PV Watt calculator provided by National Renewable Energy Laboratory. The PVWatts® energy estimate is based on an hourly performance simulation using a typical-year weather file that represents a multi-year historical period for a location with a Fixed (roof mount) photovoltaic system. https://pvwatts.nrel.gov/ For DC System Size, enter 0.1= 100W, 0.2=200W, 0.3=300W . . .

As an example, Solar production for each 100W roof mounted solar panel at 0 degrees horizontal would be as high as 6480W in July and as low as 1450W in the month of December in Jackson Center, OH. Based on this above example, 400W of solar could produce 5800W on an average December day, the lowest production month of the year. Dividing 5800W by 13.6V average results in 426AH of possible battery charging. Of course a battery cannot accept the full production of a solar array because a lead acid battery will only bulk charge for several hours, then run through a gradually declining amperage absorption stage for several more hours before it is fully charged, and then moves to float stage. Even with the inefficiencies of a lead-acid battery bank's acceptance rates, my experience has been that 400W of solar can easily keep a 230AH lead-acid battery bank fully charged with significant furnace usage, refrigerator use, water pump and lighting use under challenging late-season cloudy conditions. Here is a link to 30 days of my experience http://www.airforums.com/forums/f448...ml#post2177241

I agree that solar panels are addictive and you should consider installing as much wattage as your Airstream's roof can handle. But on smaller Airstreams, 200 to 400W may be all you can install. I have been very satisfied with the 400W of solar installed on my Airstream's roof.

uncle_bob 11-30-2018 09:00 AM

Hi

The gotcha is that the stock controller is *not* a MPPT design. The peak power point may change, but the controller ... not so much.

Also the falloff of light due to low angle sun pretty much kills any gain you might get, even with a MPPT.

Bob

Oli44 08-03-2019 11:26 AM

The Airstream Factory, in the course of installing solar, disconnects the Blue DC positive wire in the Parallax power supply. Has anyone reattached this wire, in order to be able to use a generator and the Parallax, to charge the battery, when the sun is not out to recharge with the solar system? I am told that this will not impact the solar system installation in any way, as it is an independent system, connected directly to the battery for power.

farafield 08-04-2019 05:13 AM

Quote:

Originally Posted by Acheron2010 (Post 2176155)
Not to hijack the thread, but I'd be interested in others experience boondocking with the stock 80 watt system. Has it met your needs for lights/furnace/whatever overnight or several nights?

My experience with a Lifeline AGM group 24 battery and the factory installed 80w panel is that I can be out for a couple of days using water heater, pump, refer on gas, some lights. BUT I worry about draining the battery too low because not sure how much I can trust the monitor.

I did an experiment on my last trip. I used the refer only on gas plus the parasites. I was in a shaded campsite with filtered sun. It seems according to my Sunexplorer II that my battery held its own throughout the day, then lost 10% at night.

I am not an electric wonk meaning I am doing this by "feel", not figuring out the amps per appliance etc etc. but I will probably get there at some point.

I'm not sure how much I trust the Sunexplorer II or totally understand what it's telling me. When I headed out on that last trip, I had plugged in overnight to cool down the refer and the SE II showed 85% battery remaining. Maybe my solar panel needed cleaning. My battery may not be in tip top shape.

Next time I will be sure to have my panel clean, battery at 100% and try the same experiment.

I will likely get a pair of golf cart batteries and a solar panel suitcase at some point. But for now my trips are short and I don't mind camping vs. glamping. I'm usually at a state park with water and bathrooms but no hookups.

uncle_bob 08-05-2019 07:31 AM

Hi

The panel on the stock solar setup is at best making a guess at the battery state. If solar is "running" at the time, the guess is worse than if it isn't running. It will overstate the percent you have and thus fake you out. The best number it will give you is with no solar and nothing going on in the trailer.

A somewhat better approach is to use a multimeter on the battery posts. The same qualifiers apply. You also need to convert what you get based on battery temperature. Indeed this is all a lot of work. Unfortunately the only real solution is a shunt based monitor like the Victron BMV-712.

Bob

JeffCross 08-05-2019 08:54 PM

My experience with factory solar
 
I have the factory solar with one AGM battery, I have since upgraded to two AGM batteries. (You can see my efforts in another thread.) And I have added a 100 watt Zamp panel via AMSolar recently.

My results were "surprisingly good". We boondocked 3 days in Rocky Mtn National Park in a full sun spot. We did everything we would normally do, run the heater when necessary, run the water pump, run the fan when it was a little warm, had the fridge running on propane. We also had two grandchildren who loved to leave the lights on or forget to turn off the pump.

Our meter never showed below 90%, we were 100% almost the entire time. We did clean our panels before going, so that's a plus but I was impressed and amazed at how well the batteries did with the solar.

Just my experience.

farafield 08-06-2019 04:40 AM

Quote:

Originally Posted by JeffCross (Post 2273663)
I have the factory solar with one AGM battery, I have since upgraded to two AGM batteries. (You can see my efforts in another thread.) And I have added a 100 watt Zamp panel via AMSolar recently.

My results were "surprisingly good". We boondocked 3 days in Rocky Mtn National Park in a full sun spot. We did everything we would normally do, run the heater when necessary, run the water pump, run the fan when it was a little warm, had the fridge running on propane. We also had two grandchildren who loved to leave the lights on or forget to turn off the pump.

Our meter never showed below 90%, we were 100% almost the entire time. We did clean our panels before going, so that's a plus but I was impressed and amazed at how well the batteries did with the solar.

Just my experience.

Are you using the stock monitor or did you install a new one?

uncle_bob 08-06-2019 07:38 AM

Hi

If the batteries are cold, the "magic voltages" go up. Outdoors in a cold climate they can stay cold for a while. ( = it's battery temperature rather than air temperature that matters).

The stock monitor sits inside the trailer. If it's cold out, people tend to keep the trailer warm. That's just the way it goes. Ours is right over the stove so indeed it might be the warmest place in the trailer right around breakfast time :)

A cold battery into a warm monitor can read 100% charged when it actually is at 50% ....

Bob

JeffCross 08-06-2019 08:33 AM

Factory Monitor, but always looking to upgrade
 
I am interested in updating to a more sophisticated monitor, but to be honest, I haven't looked that hard, but I am interested in finding a more accurate one that is fairly simple to install. I am not an electrician, but I am willing to learn.

Again, not to hijack this thread, but I was wondering if anyone had a fairly simple, medium expensive, recommendation as I would like to have an accurate reading of my batteries.

uncle_bob 08-06-2019 10:16 AM

Quote:

Originally Posted by JeffCross (Post 2273822)
I am interested in updating to a more sophisticated monitor, but to be honest, I haven't looked that hard, but I am interested in finding a more accurate one that is fairly simple to install. I am not an electrician, but I am willing to learn.

Again, not to hijack this thread, but I was wondering if anyone had a fairly simple, medium expensive, recommendation as I would like to have an accurate reading of my batteries.

Hi

Unfortunately there really are only two approaches: One reads voltages and pretty much guesses from there. The other puts in a shunt and does a bunch of math. Voltage monitors with temperature probes attached to the battery do a bit better, but they still have issues.

The shunt based devices all have the same basic issue - installing the shunt. It's not impossible to do on a DIY basis. It simply involves running another cable over to the shunt from the battery. You then move the leads that were on the battery negative over to the shunt. Usually the shunt gets protected from dirt and wet. That means the cables route a bit further than you might think at first.

If you are going to the trouble of installing anything at all, go with a shunt based device.

Bob

waninae39 08-07-2019 06:22 AM

look into the victron systems
free web access and blue tooth control from your phone

we use many of their products and are happy
with lion batteries be sure to measure batt temp and get a shunt to measure current

i have posted my schematic before

uncle_bob 08-07-2019 08:09 AM

Hi

Indeed the shunt based stuff does cost money. It also takes time to install. If you will be out for more than a couple days on batteries, management will get complicated. It's not impossible to do by voltage monitoring. People did it that way for years and years. You are likely to run the generator a bit more often than the minimum to keep things topped up. That was fine "way back then".

These days, you may be out and about with only solar and no generator. There is no backup to fill up the batteries. The only option is to conserve energy. The shunt gizmo tells you how much you are using (in amps) as well as the state of the battery. You have all the information you need to make an informed decision.

Bob

lsbrodsky 08-07-2019 08:16 AM

I agree, Bob. I think part of the issue is that people do not generally know what battery voltage means in a lead-acid battery and when/how to use the reading. I think once that is understood a plain old voltmeter can tell you a lot. No question that a shunt device with the "computer" to give you a variety of results is way better. I see more of our members taking the plunge and installing battery monitors, almost exclusively Victron. I wonder if Victron ever knew that they would be so big into RV's?

Larry


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