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-   -   Adding more solar and batteries (https://www.airforums.com/forums/f37/adding-more-solar-and-batteries-174231.html)

Dena m 10-23-2017 09:06 AM

Adding more solar and batteries
 
I have a 2017 Airstream motor home. I'm thinking of adding the Airstream packages for two additional solar panels and two more 12 V batteries. If I run refrigeration and one reading light in the evening, how long do you think I could boondocking with this setup?
Also, is Airstream the best one to install?
Sharing your experiences and knowledge would be much appreciated.

Dena

uncle_bob 10-23-2017 09:30 AM

Hi

I'm often confused about AS and their packages. I *think* that the standard solar upgrade both on the motor homes and on the trailers involves two AGM batteries. Put another way, you only have two house batteries when it's all done. I've been wrong before .... :)

Solar is highly dependent on the sun :) In the middle of the summer, out in the desert, it works quite well. In the late fall deep in the forest, it's not going to be much of a help. Your generator is still your friend.

To me, a "perfect" solar setup would let you run on batteries for two days. The solar would recharge those batteries in one day. That way you can have a day of shade / clouds / rain and not be in crazy trouble. Others scale things so that the solar is half this size.

You have a very finite amount of space on top of your Interstate for panels. Unless you add outriggers or portable panels, there is a maximum amount you can put up. That more than almost anything else will limit what your outcome will be. There are no "super panels" that produce 10X more power per square inch ....

The advantage of the AS package is that you can get it done at the dealer. If there is a problem with it, any AS dealer should be able to work on it. The disadvantage is that they probably don't cram quite as many panels on as a custom job could.

Some basic math (with guessing involved):

Two group 24 AGM's give 180 AH with 90AH usable

Stock solar is rated at 300W (guess practical max at 240W)

In 8 hours of summer sun, you likely get about 14A on average so 112 AH

The solar will recharge the batteries in less than a day.

Reading light for three hours is maybe 4 AH so not a lot.

Fridge depends a lot on how hot it is and how often you open the door. Guess it at an average of 1A. Over 24 hours that would be 24AH. If it is at 3A, you would be at 72AH.

Bottom line, as long as you have full sun, you should be doing ok.

Yes, there are lots of variables so this is only a guess.

Bob

old 10s bum 10-23-2017 10:15 PM

Iíve been reading up on solar for the AS thru the treads on AirFourm. I keep getting the answer, you canít run everything off the solar panel on top of the roof because there isnít enough room. Iíve been reading about solar cloth. Iím not sure if they have perfected the product yet, but when they do, Iím in for changing my awnings in to a solar system.

uncle_bob 10-25-2017 06:58 AM

Quote:

Originally Posted by old 10s bum (Post 2025669)
Iíve been reading up on solar for the AS thru the treads on AirFourm. I keep getting the answer, you canít run everything off the solar panel on top of the roof because there isnít enough room. Iíve been reading about solar cloth. Iím not sure if they have perfected the product yet, but when they do, Iím in for changing my awnings in to a solar system.

Hi

You most certainly can do an outrigger system with panels on the outriggers. Potentially you could triple the solar input that way. Whatever you do has to stand up to 100 MPH winds (40 MPH wind + 60 MHP down the road). It will be a heavy structure. Putting that sort of weight on top of an AS will raise it's center of gravity and make it a bit unstable.

Net result would be about 3X power from the sun. If you keep the same ratio of solar to batteries, you now need 3X the batteries. They also add weight and take up room. You could put them down low to drop the CG a bit. Since it's a ratio of solar to battery, the battery type does not really matter.

Some math, numbers based on a mid sized trailer:

Stock setup gives 1 day charge to 100AH

Double this is possible so 200AH with more batteries and panels on the roof.

Add outriggers and you are at 600AH with 6X the batteries you had originally. That gets you to 600AH.

If you want the "charge in one day / use for two" setup, you are only at 300AH. Let's stick with the 600AH for now.

When it's chugging along, your AC probably is pulling ~120A off the battery (might be a bit more, might be a bit less). Just how much exactly will always be a "that depends" sort of thing. Your 600 AH of solar will let the AC chug for about 5 hours. If it runs 50% of the time, you get to 10 hours. Do you want the trailer at 75F when it's 95F / 95% RH outside? That gets into this as well. Trailer is in the sun for solar ... not good for the AC ....

At some point you work out that this isn't going to fit with lead acid batteries. Lithiums are the alternative, mounted in the heated space of the trailer. That adds some issues you may or may not be happy with. If your daily budget is 600 AH, you probably want 800 AH of usable battery capacity (typical = 75% of max). That gets the total capacity into the 1,000 AH range (max discharge = 80% of theoretical).

So yes, you *can* improve things. There are a number of people who would love to do this for you. They can do a terrific job of fitting this and that in here and there. There's a bit of magic involved and a *lot* of hard work. At some point the question will come up (likely asked very politely) :) "how would you like to pay for your $30,000 upgrade?" . It is pretty common pay at least part of that up front.

Money is what always stops this conversation. The number could be a bit bigger ... Indeed if that number is *not* an issue to you, go for it. We'd all love to follow along. Please post lots of pictures !!!!

Bob

billrector 10-25-2017 07:06 AM

Wow...I thought OP just wanted to run refrigerator and reading light!

DreamStreamr 10-25-2017 07:07 AM

Friend and his wife from San Diego have 3 100w panels on their Airstream Interstate and 4 80amp hour batteries. He and I, parked side by side at Albuquerque Balloon Fiesta dry camping a couple of weeks ago, each used about 45 amp hours each night from sunset to sunup ("panel sun"). I have 250 watts solar (tilted) and 300 amp hour battery capacity.

We both recharged to 100% by 5 or 6pm each day. He "cheated" a little, running his generator for 10 minutes each morning. I think he was making coffee or toasting something. It was nice having the quiet power, no starting/stopping/refueling. Love it.

lewster 10-25-2017 07:19 AM

HI Dena,

Let me be quite specific about the solar you intend to install.

First, you can put up to 400 watts on your roof. Next, it is especially good to install 4 GPL-4CT batteries at 220 amp/hours usable (440 amp/hours total)if you are so inclined, or larger for your battery bank (unless you want to go lithium, which is another story completely).

You should also add a 2000 watt Magnum inverter/charger to this system to charge the batteries (takes 2-1/2 hours for a complete recharge at the Magnum's 100 amp charge rate) along with the required ME-RC controller and appropriate wiring. This will allow for the complete use of your entire coach on the inverter when off-grid.

I use these components all the time in my solar installations and they will definitely give you what you are looking for. BTW, the fridge in a '17 draws between 5-6 amps per hour, not the 1 amp that was suggested earlier.

Thanks!:D

TravlinMan 10-25-2017 08:31 AM

Have ya tried doin it with what ya got before ya spend tons of money? Ya said two 'additional' panels, so I assume ya got at least 1 panel already?

I have got an ARB fridge in my truck, which is a compressor fridge like the interstate has, and I am able to run it indefinitely using a 100w panel and 1, 12v battery. I use a folding, 100w briefcase made by Renogy, which was about $200 a few years ago. I also have an additional 100w renogy panel for the trailer, which is all I have needed to run my lights and radio and charge my devices at night. That 100w panel (also portable) will charge the two 12v batteries that came with my International by noon each day, even on cloudy days.

I find this is all I have ever needed to boondock for weeks at a time and my setup cost just a few hundred bucks.

https://www.amazon.com/Renogy-Watts-...NK6?th=1&psc=1

Dena m 10-25-2017 09:02 AM

Adding solar and batteries
 
Quote:

Originally Posted by lewster (Post 2026205)
HI Dena,

Let me be quite specific about the solar you intend to install.

First, you can put up to 400 watts on your roof. Next, it is especially good to install 4 GPL-4CT batteries at 220 amp/hours usable (440 amp/hours total)if you are so inclined, or larger for your battery bank (unless you want to go lithium, which is another story completely).

You should also add a 2000 watt Magnum inverter/charger to this system to charge the batteries (takes 2-1/2 hours for a complete recharge at the Magnum's 100 amp charge rate) along with the required ME-RC controller and appropriate wiring. This will allow for the complete use of your entire coach on the inverter when off-grid.



I use these components all the time in my solar installations and they will definitely give you what you are looking for. BTW, the fridge in a '17 draws between 5-6 amps per hour, not the 1 amp that was suggested earlier.

Thanks!:D


Thank you so much, Lew. Guess battery kits are on backorder from Airstream. Adding another panel now and likely another when I have batteries installed. I'm sure I'll enjoy my Interstate once it's equipped for my style of glamping. Sure wish your business was in So Cal!

Dena


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