Un-mounted Solar Panel Options?

[Suanne]

I'm hoping that you all might be able to help me think about how to meet my electricity needs this winter, using un-mounted solar panels.

Here is some background:
-I'm planning to boondock (solo) in our 20' Class C this winter in the desert SW. I will be testing to see if I like snowbirding, staying relatively stable for 3 months.
-I will temporarily modify the inside of our RV to be closer in form and function to a fullsize van (reducing storage, living area, and amenities). Although I'd prefer to do this test in a van, I'm not ready to commit to one yet. And, because I'll be waiting out any bad weather, I want something roomier than my Prius.
-Assuming I like snowbirding during this test period, I'm saving money to purchase a van to modify.

Our Class C currently has two 6v Interstate Deep Cycle Extreme batteries, 122mins @ 75Amps, 232Ah, less than 2 years old and in good condition. I understand a portable 100W suitcase solar system would not provide enough power to both return the amount of power used each day and bring the batteries back to a full state of charge by daylight's end.

So, I'm now trying to figure out what to do for electric power this coming winter. I don't want to mount any solar panels onto the Class C because they wouldn't be used on the RV once I get a van. What ever solar power investment I make for boondocking this winter in the RV will be ported over to its permanent home on a full-size van (probably medium-high top).

My electricity needs are relatively small except that I'm on the computer about 8 hours each day/evening for communication, research, website maintenance, photo editing, writing, reading, commerce, etc. I don't watch movies or game. I expect my computing devices to include a Dell Venue 11 Pro tablet w/keyboard, Verizon Jet Pack, and Wilson Sleek booster. I'll also re-charge a smart phone, and occasionally AA/AAA batteries, a toothbrush and maybe an electric razor. When hot, I'll run a Fantastic Fan. I use LEDs for lighting.

I don't know the actual power usage of these items. But, I just ordered a Kill-A-Watt meter and should have some real numbers within a couple of weeks. However, based on a previous post, the 232Ah capacity of my RV's batteries is probably more than I need. If 75Ah is enough, could I get away with using the 100W suitcase solar system? The only other portable option that I can think of is a Unisolar 128W flexible panel. If I got one of those, would it keep a 100Ah battery healthy?

In addition, I'll have a Honda eu1000i generator with me to do some charging, even though I really dislike the noise. And, I can also recharge the house battery and devices a little bit during drives into town (approx 12 miles every 10 days).

I'm posting this now because I hope to find out what else I need to consider, even before I have the numbers off the Kill-A-Watt meter. Although I've certainly studied many posts and blogs about solar power, I'm still very much in learning mode. Are there any other options out there for un-mounted panels that might meet my electricity needs this winter?

Thanks for any help or direction you can provide.

Suanne

 

[SternWake]

Basically any framed solar panel can be made portable. They are not really heavy, all you need to do is find a way to support it so that it faces into the sun and cannot blow over, and perhaps a method to keep it from walking away.

Running some 10 awg mc4 cables from panel into a a good connector like the 45 amp anderson powerpoles will allow you to easily disconnect it from the solar controller.

There are two types of solar controllers. PWM and MPPT. Mppt can harvest more in cooler temperatures at lower battery voltages, but for the price of a MPPT compared to PWM, one can either get an additional panel, or perhaps a bigger panel.

Generally Bigger wattage panels are 24v nominal or higher voltage panels, and these require a MPPT charge controllers. Higher voltage panels are good because you can use longer cables without suffering as much voltage drop, which is the nemesis of all 12v DC systems.

The Unisolar 128 is 16 feet long, too big to adhere to a Van roof, And I've read more than one report about them failing when used as a portable panel, rolled and unrolled daily. They have minimum rolling diameter and I suspect these users went a little thinner and broke some intercell connections.

I have a Unisolar 68 in addition to a framed Kyocera. My 68 came rolled up in a narrower diameter than Unisolar recommended, but it works fine.

I'd really urge you to acquire as much solar as you can fit on your future van's roof, and can easily carry by yourself and which you can store easily when driving or pulling the panel inside the class C RV overnight, if thievery is a concern.

It is very difficult to have too much solar, and the more you have, even if it is excessive, will just make your batteries happier and reduce your stress. You will not have to worry about the drive into town to charge things and actually be able to recharge closer to the battery manufacturer recommended bulk rate while also powering your computer equipment. Basically all you would need to do is move the panel to face the sun 3 times a day, and you would harvest more, much more than if the panel was mounted flat on the RV roof.

Interstate GC batteries are made by US battery and US battery recommends a 10% bulk rate which would be 23 amps or close to 400 watts of solar.

Since you have the Honda you can get a 30 amp or slightly higher amp charger and feed these batteries once a week with that 30 amps for a few hours and keep them happy enough, and even a quick generator blast in the morning daily with your morning coffee or something else for 15 minutes or so, and it will help greatly to met these higher bulk currents that make the batteries so much happier, and let the solar silently power your computer stuff and charge them until sundown.

It is not as if Not meeting the manufacturer recommended minimum bulk current is going to cause the batteries to die extremely prematurely. Since you will have other options concerning charging with the Honda you don't have to stress being able to have solar capable of making 23.3 amps. GC batts are pretty tolerant and should give pretty good lifespan, it is just they they will appreciate all you can give them when you do cycle them down to 50%. The more solar you have will mean less you will discharge them when working throughout the day, and can splurge a bit more come nighttime, and then yo might not even have to bother with the Honda until the rare cloudy day moves in.

 

[cyndi]

Reiterating what Stern Wake said. I purchased the UniSolar ePVL-144, with the intention of rolling it up, rather than affixing it to the roof of the moho.
http://www.amazon.com/UniSolar-ePVL-144-Laminate-Amorphous-Solar/dp/B00CGAEJCW

Within a couple of weeks you could see places where the panel was breaking down. It was then mounted to the roof.

Isn't Bob selling a portable suitcase kit?
http://www.cheaprvliving.com/?s=suit+case&submit=Go

 

[Optimistic Paranoid]

If I were doing this, I would go with a rigid, framed panel, for the reasons Sternwake and Cyndi said. The only tricky part will be figuring out how to transport it safely when you are driving. You will need some kind of padding, and some way to secure it so it doesn't move around. If you decide to go with TWO panels, the padding becomes even more important, so they don't damage each other in transit.

Regards
John

 

[Bela's Mom]

Suanne, when I decided to start a solar system, I also wanted a portable set-up for several reasons that I won't go into now. I decided against the suitcase panels/kits as I would then be stuck with the built in charge controller and could not add panels to the system later if I wanted. I already had two metal sawhorses and I decided to use those as a stands. I don't need as much power so my system is smaller but here it the picture of what I did that may give you some ideas. That is a 70 watt panel and I have two of them for 140 watts. I only have 100 ah battery.
Like Sternwake said, the panels are not heavy, so if you can find/or build some kind of portable stand, you can attach the panel to it. As the sun gets higher overhead, I just place an adjustable curtain rod under the free end to bring it up flat. I use the shadow the stand and panel make to know that I have it pointed directly at the sun. I use 12" stakes and bungee cords to stake the stands down to the ground if it is windy.

While this is a bit more labor intensive than on the roof, I get the maximum sun exposure by tracking it, and I don't have to climb up on my super high roof Sprinter van to clean the panels. I also don't have to worry about shadows on the panels made by the roof vent,air conditioner and tv antenna.

Hope this helps a bit.

 

[Willy]

One thing I'd like to take issue with is "..Generally Bigger wattage panels are 24v nominal or higher voltage panels, and these require a MPPT charge controllers.." and NOPE. I have THIS PWM charge controller (under a different name, but same guts) and the input voltage is max 30v. ..Willy.

 

[Suanne]

Thank you, thank you, thank you -- SternWake, Cyndi, John, Jo and Willy.

I'm seeing that framed solar panels are the way to go. I already have a couple of portable saw horses for supports. And I could easily store, pad & secure everything above the cab where a queen mattress currently resides.

If I can figure out how to get them to fit on the roof of my future van, two sounds better than one. They would keep our current 6v's happy enough, and be more than enough for the lower capacity size battery I get for the van. More is better

Now, to figure out all of the other components for this system, and how to set them up ... MPPT controller placement, do I need a smart charger, where/how to run the wires, etc.

Thanks again, Suanne

 

[Spaceman Spiff]

This is about all I can add to the conversation, as I am trying to size my system also. Will give you some numbers for what a fantastic fan will draw:
http://www.wanderthewest.com/forum/...an-vs-maxxfan-comparison-including-amp-usage/
-- Spiff

 

[Willy]

One option, given limited room on your van roof, is to have one panel mounted and running lengthwise on the roof, with the other hinged to that panel and running lengthwise too. When driving it would be folded over and locked, opened up when parked for a bit. ..Willy.

 

[Optimistic Paranoid]

As far as the MPPT controller goes, the rule of thumb for an optimized system is that the controller should be located as close to the batteries as possible - without actually being in the same compartment as the batteries themselves, of course.

Wires from the panels to the controller as long as necessary, wires from the controller to the batteries as short as possible.

Appropriate sized fuses ( or circuit breakers ) in the hot wires on both sides of the controller. The panel to controller fuse should be as close to the panels as possible. The controller to batteries fuse should be as close to the controller as possible.

Always fuse a wire BEFORE it goes through anything it could short against if the insulation failed. Fuses AFTER that point provide no protection at all.

Regards
John

 

[SternWake]

Here is a larger wattage Nominal 24 volt panel, look at the VOC and VMP

Well over 30 volts.

http://www.solar-electric.com/solarworld-sunmodule-sw275-monocrystalline-solar-panel.html

Whether the PWM controller will just clip the extra voltage and turn it to heat, or the extra voltage releases the magic blue smoke, is anyones guess.

 

[Willy]

Here is a larger wattage Nominal 24 volt panel, look at the VOC and VMP

Well over 30 volts.

http://www.solar-electric.com/solarworld-sunmodule-sw275-monocrystalline-solar-panel.html

Whether the PWM controller will just clip the extra voltage and turn it to heat, or the extra voltage releases the magic blue smoke, is anyones guess.

The 30v is, I believe, for a 12v system.. it can go up to 55v for a 24v system. operating manual ..Willy.

 

[akrvbob]

I was selling suitcase systems, but now Amazon is selling them for less so I stopped selling them and recommend Amazon instead.

I wouldn't be so quick to give up on the suitcase systems. Two of the 100 watt panels would be all you need. It's true you will pay more per watt but it might be worth it.

Are you going to pull a toad? If not you are going to have to muscle those panels in and out every time you want to go somewhere. I think that will become a real burden on you.

Plus you can find shade in the desert and being able to park in the shade and EASILY move the portable panels out to the sun will be great.
Bob

 

[Suanne]

Bob, If I could connect the suitcase solar panel systems together, that would seem like a better solution. But, from what I've read on amazon.com, you can't connect them. I won't be pulling a toad. The panels I'm considering are 160W, 58x26", 25.5lbs (http://www.amsolar.com/home/amr/page_33_20/go160_solar_panel.html). It'll be a hassel to move 2 of them in and out every 10 days for sure; but I'm not sure it'd be that much more of a hassel than moving 3 of the suitcase systems. That's my thinking in theory anyway.