I know that this must be a previously discussed question, but I never seem to have any luck with the forum's search feature in finding previous articles. 

Anyway, I have a 2017 178 and would like to buy a suitcase solar panel for dry camping. I want to stay at a modest budget of $300 or less (hopefully $250 or less). I really know nothing about this subject so any advice would be appreciated. When dry camping I do not plan on using much electricity, but would simply like to be out a week or two while using minimal lights, radio etc., without the batteries going under the recommended charge levels. My R-Pod has 2 6V golf cart batteries. 

When I buy a suitcase solar panel I want to make sure I have 100% of all necessary items to hook it up and utilize it. I know that my R-Pod is prewired for solar, but that is about the extent of my knowledge :)

I would of course like to buy the best unit available for my budget.

Thanks in advance for any and all suggestions and information.

Sincerely,

John 

If you're still really wanting a solar option, I recommend http://www.rpod-owners.com/forum_posts.asp?TID=5017&title=connecting-a-100-watt-solar-panel-to-zamp-port - this thread . 

This https://www.amazon.com/dp/B00B8L6EFA/ref=asc_df_B00B8L6EFA5294242/?tag=hyprod-20&creative=394997&creativeASIN=B00B8L6EFA&linkCode=df0&hvadid=198107824285&hvpos=1o5&hvnetw=g&hvrand=3172157931545674147&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9031721&hvtargid=pla-348805311526 - 100 amp system  (edit. 100watt)from Renogy is a deal and a good place to start if your elec usage is low and there is sun. Mine recharges my batteries fully every day in the summer, not so much in the winter.

 If you really plan for a week or two off grid You may need more like 200 watt system and /or a small inverter/generator that can be used to charge the batteries. or like Will said, use your tow vehicle to charge.

rgds John

Little oops there, '100w' system..Nice though. PWM controller that's 30a. Room to add another panel (or 2) with changing the PWM controller.

Scroll back up to his response, where it says "this thread' it's a link.

http://www.rpod-owners.com/forum_posts.asp?TID=10976&title=charging-your-battery-from-your-tow-vehicle - This is the link to that thread, which is still 'active'.  The other link I posted earlier is to a thread on how to connect a 100 watt solar panel to your Pod's battery, particularly if you have a Zamp port.

Basically, all you do is run a set of inexpensive battery clamps from your tow vehicle to a charge controller (between 10 and 30 amps) and then run another line to the Pod's battery from the charge controller either with another set of battery clamps or by plugging into your Pod's Zamp port if it has one.  The gauge wire needed depends on both the amperage of the charge controller and the length of the wire, but if each length is no more than 10 ft., 16 or 18 gauge wire is fine (my 10 amp charge controller came with sufficient lengths of 18 gauge wire).  Then you just start the car and let the charge controller gently and safely charge up your Pod's battery.

A simpler approach is to use jumper cables, but this is not as healthy for deep cycle batteries, which are designed to be charged in a slow, controller manner, which jumper cables absolutely cannot do.  But in a pinch, they will work as well.

Will, has shown a simple way to control that re-charge with the system supplied with your solar kit/package.

What can 'you' live with or without? That is the real question at hand.

A good set of dual 6v batts will get you there. And you really don't have to spend a lot to get there.

Me, I'm going to draw a bit more than Pod, yet it is still workable.

The only mistake in my mind is not camping! So is my opinion...

Share your decisions and we all will grow from it.

In our 177, I mounted it on the rear wall of the storage compartment in the rear of the unit.  It just screwed in with shallow screws, and we never had a problem with it.

https://www.costco.com/.product.100389117.html?&EMID=B2C_2020_0116_Automotive

$119.99

Thanks

First, the hyperlink is now active if someone wish to have a look (on this reply only).

It's 100 watts of solar with a $20 controller. Priced about right for what it is, $1 a watt. Look at the size and decide how you will store it. I do like it's a panel vs. 3-4 panels connected (like HF). I also like it is Hard framed and the back connectors are correct (unlike HF). There are no final connectors on the leads and you will need to solder and protect them (not a deal breaker). Do realize this is pba based battery system, not lithium. You would replace the controller for one designed for Lithium if you so wished.

Not an unreasonable purchase as an entry to solar. You can always upgrade as you go and can afford. 

I have the same type panel I bought several years back at $1.50 a watt (mine is a 130w) and it was a steal at that time! 

Well, you need to calculate your demand in watts times the hours you will use whatever it is.  That is watt-hours  Then, size your panel(s) to generate that many watt-hours during a 6 hour charging day (average hours of full power generation in a day). 

So, if you run 20 watts of lights x 6 hours, 80 watts of TV x 4 hours, 10 watts of ventilation x 8 hours, you have 120 watt-hr + 320 watt-hr + 80 watt-hr = 520 watt-hr.  You need a 100 watt panel (100 watts x 6 hrs), it you set the angles for best generation.  A little higher panel wattage will not hurt.  Your Watts May Vary.

Size the battery bank for your load x 3 days of no sun and double that so the battery doesn't drop below 50% charge.  520 w-h x 3 x 2 = 3120 w-h.  Divide watts by 12.5V and you get 250 Amp-Hr.  That's a lot of battery, but you get the gist.  You may find it acceptable to run with 1 or 2 days reserve and then recharge with your vehicle, or a small, suitcase gas generator.  Two Group 24DC batteries like my 180 has would be 150 a-H, almost 2 days. 

Its better to run this calculation in amp hours than in watt hours. This is because if you do it in watts hours you aren't taking into account the losses in the solar module and battery. If you do it in amps and amp hours those losses are taken care of automatically.

Measure each of the loads in amps using a clamp on multimeter. Multiply each by the number of hours of daily operation and add them up to get total load amp hours per day. Divide that number by 4 for a less sunny area or 5 for a sunnier area. Look up the max power current rating  (not the watt rating) of the solar module you're interested in and be sure that its that value or higher. That should run your loads indefinitely on solar in a clear location in spring, summer, and early fall. If you only want to extend a battery charge for a few days of camping you can get a smaller solar module.

You can use the daily amp hour number you calculated to size your battery as discussed in the post above. 

I disagree with this philosophy, as you then have to compensate about series/parallel issues. I have for years just converted batteries and loads into watt-hours. Then you can deal with each battery and load as just a "box of watts". As it happens, when battery voltages go up and down, the current (amps) will go down and up. The watts pretty much stay the same.

You will also notice that the industry is moving that way too. The batteries in EVs are listed and used as watts and watt-hours. 

It just simplifies things all over the place.

There are no series parallel issues on our 12V systems. And, its very easy to measure your loads in amps using a clamp on dc meter. Watts measurements are a lot more difficult. The reason EV's are rated in kwH is for comparison purposes because each manufacturer uses a different operating voltage. That has nothing to do with the simple little 12V power systems in our rPods.

Working in watts actually makes things much more complicated. Batteries and solar modules are not boxes of watts. If you do the calculations in watts and watt hours you have to take into account several derate factors which are built in if you work in amp hours.  Lead acid battery round trip efficiency is about 85% and solar modules never produce their rated watts due to the way then are measured at the factory. They are also designed to produce more voltage at max power than a battery can normally take so unless you are using an MPPT charge controller there is another loss there. Overall, by treating batteries and solar modules as lossless boxes of watts you will overestimate system production by something in the range of 30-35%. 

I've been designing solar modules and systems for 40 years, I assure you that amp hours are much simpler. If you really want to use watts and watt hours you can certainly do so, but you have to build in about an 85% efficiency for the battery and about an 80% multiplier for the solar module(s). You will get to the same answer either way, as it should be. 

Not to take away from the OP's question and would love to discuss further with both you and GG. I believe the entire group could learn the benefits of each side of this. One of you wish to start another thread?? I for one am interested in the conversation.

Most appliances and devices report watts consumed, not VA.  For most people, using watts and a lowish 12.5V for the system voltage is simple and easy.  That should comfortably account for resistance losses in the system.  This is a design exercise intended to get to a useful system without unnecessary expense and weight from over-kill.  YWMV. 

My PV panels are fixed, but some times of the year, I get a pleasing 85% of rated outout, at the battery.  Azimuth and elevation angles are important to performance, but you can control that easily enough when boondocking. 

A good site for establishing angles. 

https://www.solarpaneltilt.com/

Oh dang, just when I was gonna tell yall all about the swap here at my place (with three phase) that the electric co-op did, swapped 3 old transformers that were 10 KVA for 3 new transformers that are 5 KVA...

Go ahead and use reported watts on your trailer DC loads if you can find them (and you believe them). Or, you can measure the loads quickly and easily in amps with a clamp on hall effect meter, or with a current shunt if you prefer.

12V batteries are rated in amp hours, so if you work in watt hours you have to convert back to that for the battery sizing anyhow. 

Lead acid batteries have a round trip efficiency of about 85%. But, their coulombic efficiency (amp hours out over amp hours in) is essentially 100%. Their efficiency loss is in voltage. You charge them at 14 plus volts and discharge them at a bit over 12V. Hence the 85%. But, if you work in amps and amphours you don't need to take battery efficiency into account, its taken care of.

Now on to the solar side. If you look at the Vmp (voltage at max power) in the spec of a PV module intended for 12V battery charging you will see that it is generally in the 17-18V range. Why so high to charge a lead acid battery at only 14-14.5V or so? 

ROTFLMAO!!! How's that workin' out for ya? 

At least the part of what offgrid wrote that I read is correct.  But, offgrid, you miss the point.  This isn't Physics class, it's handbook engineering, because people want a quick, easy answer and there's bills to pay. 

Setup the panels and let's go fishin' (or huntin', shootin', whatever). 

Very well so far. 

Its a long story and would be a thread detour but yeah, we downsized the 3 phase power here. This building used to be a commercial business....but I'm converting it into a residence, and was only using about 5% of the rated transformer capacity, and the electric bill is based partly on kwh used, and partly on available capacity, so yeah, we downsized the hardware on the pole...saving me about $25 a month....

The transformers are rated in KVA....that's really the only tie-in with the thread.