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housedhs

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Sep 12, 2017
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I'm in a Kodiak B+, about 21 ft.  I just replaced the majority of cabin lights with LED bulbs (https://www.amazon.com/gp/product/B00X27XPMS).  I want solar to store energy efficiently and power my cabin lights, my ceiling fan, my wall outlet for periodically recharging phone/computer, and eventually maybe a television.

Doing a rough measurement, I have three spaces of 5' x 2.25'.

It looks like I could fit three of Renogy's 100w monocrystalline panels.  An experienced RVer friend sternly suggests an MPPT controller, which Renogy also makes.  I'm also thinking of a 200 aH Renogy gel battery.

I see those products readily available on amazon. 

It's not the cheapest kit, but my plan is to live full-time and boondock in the RV soon.  So I want something that will work commensurately.

Does anyone suggest  anything?  A different retailer or different equipment?

Thanks, folks.

Daniel
 
I did not do this, however I know others have used the higher density residential panels (Sunpower?) which would yield more output in the space you have and might be something to consider. They do cost more.


Good advice on the MPPT controller  :))
 
Just looked at a renogy 20 amp and it appears to have good features such temperature compensation, equalize etc. I wouldn't necessarily buy a gel battery. If you want to stay away from watering a battery or you need it inside the RV get an AGM.
If you can handle maintaining wet cells and have enough height clearance a pair of  GC2 are pretty good.
 
An MPPT controller would probably be the way to go with 300 watts of solar, especially if you knew you were going to be running your batteries down a lot while boondocking. I would strongly recommend not using a Gel cell battery for RVing. Gel cell batteries use lower charging voltages, and take longer to fully recharge than "standard" lead/acid batteries. They are also not very tolerant of overcharging.

When measuring the space you have for panels, remember to factor in adequate space between the panels and other objects on the roof (AC covers, vents, antennas etc.) Just because a panel will fit somewhere, doesn't mean it should be mounted there if other objects would shade even a small portion of the panel. Shading just two or three cells is often enough to reduce a panel's output to zero.

Renogy makes good products. Pay close attention to the length of wire runs and the thickness of the wires. It can make a big difference. Remember that solar is just an alternate method of recharging your batteries. No 12 volt appliances actually run off solar power in a typical RV installation. They run off the batteries and the solar panels simply charge the batteries.

A/C wall outlets and most TVs are part of your RV's 120 volt A/C system, so when boondocking without a generator, you'll need an inverter to power those outlets and the A/C appliances that are plugged into them. Inverters invert 12 volts D/C from your RV's batteries into 120 volts A/C. Inverters must be sized (balanced) to your battery-bank's capacity, because a large inverter can quickly drain a low capacity battery-bank, and 300 watts of solar won't help much.

Kev
 
Sun2Retire:

I know others have used the higher density residential panels (Sunpower?) which would yield more output in the space you have and might be something to consider. They do cost more.

Price per watt on residential panels is very attractive as they are becoming commodity items.  72 cell residential panels also output just about what most MPPT controllers want for voltage, without having to put any in series.  This means somewhat less of an issue with shading, as a shadow will only affect the shaded panel and not any other(s) in series with it.
Frank.
 
Yup, shading on one cell of a series wired system will affect the whole system. Shading on a parallel wired system will only affect that panel. Either way, shading is a bad thing, and one should design and install the system so there is no shading. When looking at panel placement, remember to open your vents if they don't have vent covers on them, and raise your tv antenna.
 
I had one other simple question.

If I'm on a Ford 350 truck, do I need to factor in the weight of panels?  I'll almost certainly get 300 watts' worth.

Flexible panels are obviously lighter, but also more expensive.

Thanks for the info...
 
One always has to factor in weight. But 100 pounds one way or the other is not likely going to make a lot of difference. Solar panels are not that heavy.


Frank.
 
My 130's and 160's are about 26 lb each. If you shop for flexible panels pay attention to a couple issues that people seem to have. They have a dimple like surface so they accumulate a dirt spot in that dimple. Depending on how often a person wants to go up to wipe them off it may not be an issue. It may also be more of an issue for those with morning dew which helps form the dirt spot.

They also had heat issues with some because of no air flow under the panel. It was a couple years ago that I read of those issues so maybe they have been resolved or were limited to some manufacturers.

You want the panels an inch or so off the roof. AM Solar sells a nice tilt bracket. I'd make them tilt even if I never tilt them. Just me.
 
It has been my understanding that generally a MPPT controller is best served in the following situations, on 500watts or more, high voltage panels or a mixture of panels.  There is a lot of marketing swaying consumers to MPPT and they make some claims which if not questionable for smaller applications, would only be realized in ideal conditions.  I have been using a PWM controller with lots of success, first on my TT with 320 watts and now my TC with 420 watts.  There are some excellent PWM controllers on the market that will rival the cheap MPPT controllers and less money, which IMHO are nothing more than a PWM controller the mfg throws the MPPT label on.  If you do decide on a MPPT I would spend the dollars and get one of the higher quality ones. Before deciding on panels etc. I would do an energy audit to determine your needs rather than look at the space you have and try to fill it.
 
Gizmo:

I would do an energy audit to determine your needs rather than look at the space you have and try to fill it.

Hah!  And I would say just the opposite!  ;D  Good thing we are all different.  Would be a boring world.  :eek:

The plus that I see to covering every inch of the roof with panels is that you can never be too rich, too thin, or have too much solar.  ;D  AND, if one uses the commodity residential panels, the price/watt is very attractive.  I also found that the cost of the panels is 'relatively' small compared to the rest of the system, which includes a controller (big $), and shipping (also big $ depending on where you live).  Residential panels pretty much require an MPPT controller as their output is in the 40v range.

The REALLY big watt panels  come built from 6" ingots for the cells, but one can find narrower panels made with 5" ingots that will fit on either side of roof vents, a/c units, and so on.

However, housedhs  is interested in weight.  Panels are not heavy.  And, housedhs asks about his F350 with regard to panels and weight.  The panels are probably going to go on the towed vehicle, rather than the truck.  ;)  The towed vehicle is going to have a maximum weight limit, regardless of the vehicle towing it.  So, as long as the fully loaded weight of the trailer is within the specs for the trailer, and the tow weight of the F350, all is probably good.

Frank.
 
Incidentally this is what I assembled for a solar rig for the RV. I just used the Amazon Shopping app, it was the easiest to search on.

I welcome feedback, potshots, tomatoes...

Renogy 200 Watt 12 Volt Monocrystalline Solar Starter Kit with 40A Rover MPPT Charge Controller https://www.amazon.com/dp/B06VY9DVY9/ref=cm_sw_r_cp_apa_zH2kAbZP3XAHR

Renogy 100 Watts 12 Volts Monocrystalline Solar Panel https://www.amazon.com/dp/B009Z6CW7O/ref=cm_sw_r_cp_apa_jJ2kAbPGJRGV7

Renogy Deep Cycle AGM Battery 12 Volt 200Ah for RV, Solar, Marine, and Off-grid Applications https://www.amazon.com/dp/B075RGX1WR/ref=cm_sw_r_cp_apa_LJ2kAb6CWP46T

I priced a solar kit with four 100w panels, but the above configuration was cheaper.

I need to keep this around $1000. I am interested in a larger battery bank than one 200ah agm though, and I would also like to add an inverter with whatever adapter would distribute the AC power to all my cabin outlets. I just find that gear pushes me way over $1,000.
 
I think the 200 watt Renogy panel system with the 40 amp MPPT controller would work fine in a 21 foot RV. The controller is a bit more than you'd need for 200 watts of solar, but it would accommodate more panels if you decide to expand, so that's good.

PWM controllers work just fine on most RV solar installations up to about 300 watts. In fact, PWM controllers can work well on even much larger systems, but only if the batteries don't get drawn down very far. RVers, however, tend to draw their batteries down pretty far overnight. Since PWM controllers don't have the ability to convert excess voltage to amps, like MPPT controllers do, it can take a lot more time for a PWM controller to fully recharge deeply discharged batteries.

Installation is everything when installing solar in/on an RV. Here are some tips...

1. Don't allow any shading on the panels
2. Use as thick a gauge wire as you can from the panels to the controller, and even heavier gauge wire from the controller to the batteries (2 or 4 gauge works well)
3. Keep the wire run as short as possible, especially from the controller to the batteries
4. Install the controller as close to the batteries as possible. If you're going to use AGM batteries, it's OK to put the controller in the battery compartment. If using standard lead/acid batteries, put the controller in a separate compartment.
5. Put an in-line DC cutoff switch between the panels and the controller, and between the controller and the batteries. This isn't mandatory, but it's very helpful if you have to do any maintenance
6. Install an appropriately rated fuse between the controller and the batteries, and put it as close to the batteries as possible 

You don't need/use solar when plugged into shore-power, so I'm assuming you're planning on doing some boondocking. Knowing your battery's state of charge (SOC) is important when boondocking, and the typical battery indicators in most RVs do a poor job of indicating SOC. A good battery monitor is a must when boondocking. I recommend the Trimetric RV 2030. In my opinion, boondocking without one is like driving without a fuel gauge.

Kev
 
Really appreciate the info, especially the monitor suggestion. I was thinking the same thing about keeping tabs on my battery level, just couldn't find good info for a monitor. That's awesome.
 
Can anyone suggest an affordable way to get help installing the system? I need to remove a TV antenna, and make sure it's securely patched and sealed. I'm located in Dallas, and willing to bring the RV and gear to a different location too.

Thanks for being so tolerant and helpful with all my questions...!
 
Here is an affordable way to get help with your installation.  How about some free help.

Bring it to the Quartzsite Rally.  I will have a full workshop with tools onsite and you will get lots of advice and maybe even some hands on help.  There are two Solar vendors in town so if you need any additional parts you can get them.

Several of us have Solar installations and we do have a fair amount of experience.

The biggest downside is the distance from Dallas.  If you are retired and have the time it would be worth the trip and the weather would most likely be better than Dallas.
 
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