FWC Raven panel placement & 200W solo or 2x100W duo?

Stokeme

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Hello … great to be back again with a 3/17 Raven install. Simple open shell, will add one cabinet. With previous Grandby, my 2x100W roof solar was ample to charge 150 aH LiFePO4.
Any thoughts, pros/cons, about using 1- 200W panel vs 2- 100W panels? With 2 1/2 feet less roof length, this leads to ask Raven owner’s about panel placement with only one roof fan? Looking to order panel(s) ahead. Appreciate any feedback.
 
As Vic wrote the biggest single panel you can fit is probably the best choice. It will cost less and weigh less than any combination of smaller panels that provide the same (or even less) power.

Generally I recommend looking at residential type 300 to 400 watt panels. If it will fit, a quality (LG, REC, Panasonic, Maxeon, etc) 72 cell panel is recommended. Cost for the panel will likely be around $275 - $320.

60 Cell panels produce 270 -300 watts​
72 cell panels produce 350 - 400 watts​
96 cell panels produce up to about 500 watts but are often too bid for a pop-up camper roof that has vents​
Solar DesignWidthHeightDepth
60-cell39”66”1.3” – 1.6”
72-cell39”77”1.3” – 1.6”
96-cell41.5”62.6”1.38”

You will need a solar controller that can handle a 40v - 50v panel that outputs 10 - 12 Amps. (the solar controller will convert that to the 12v input for your batteries such as a Victron 100/20 (or equivalent). See table here:

I hope this is helpful

Craig
 
I'll be a contrarian with the philosophy "less is more". We get along fine with a single 100W flex panel that I throw on the roof in camp. Our 100 Ah battery rarely drops below 80% SOC. Energy uses include 65 liter fridge, propane heater fan, lights, charging devices, and a 50W electric blankie that uses 10% battery capacity if on for 3 hours. Honestly we just use solar to save a little gasoline, unless we park for more than 3 days. We've parked up to 6 days in sunny weather and the battery reaches 100% SOC by noon. Hopefully the lack of permanently mounted roof panel saves us a bit of gas, due to reduced drag.
 
These campers are so aerodynamically awful that anything going on within 3 inches of the roof surface more than two feet back from the front of the overhang and in a few inches from the sidewall makes no meaningful difference in drag.
 
Agree Jon, there is so much dirty air going across the roof. I would not worry about wind drag being constant up there on surface mounted items four inches up. There is also pockets of negative pressure as most find their front mechanical vents opening up while driving.

All this is constantly changing as you drive into different wind currents and directions at different speeds.
 
Rubberlegs,

I don't understand how your battery stays above 80% SOC from a 100 W solar panel without having a separate source of recharging.

Everything I have read about 12 v refrigerators leads me to believe that the 24 hour power consumption is 30Ah - 40Ah (depending on manufacturer and model) in 70 - 80 degree weather and higher in hotter weather.

Looking at some manufacturer specs for electric blankets shows they draw 3 - 4 amps per hour. So 3 hours would be 9Ah to 12Ah.

Not counting the power to run the fan from the heater, roof vent fans, internal lights, periodic use of a water pump (if you have one), recharging phones and other devices. It seems your daily consumption would roughly be between 40Ah and 50Ah a day.

With clear skies and a well pointed panel a 100w solar panel will produce 30Ah - maybe 35Ah a day at best.

Seems to me even in ideal conditions the panel would be barely recharging the battery if not slightly falling behind everyday.

Consumption of around 40Ah per day is consistent with our experience in our camper on late spring through early fall use. We need more power in early spring, late fall and Winter. We originally had a 100W panel. When we experienced cloudy days or rainy days the panel could not recharge the battery every day and it got lower and lower.

I looked at adding a second panel and found that a single 300W - 350W panel was marginally more expensive than another 100 W panel and that the weight of the single 350W panel was less that two 200W panels.

I am talking about rigid panels. I am not aware of any semi-flexible panels over 270 W. Also, a good quality 200W semi flexible panel is close to the price of a 350W rigid panel.

I made the conversion several years ago when semi-flexible panels were frequently failing within 12 - 18 months of purchase so I decided to stay with a much more reliable rigid panel. I have read accounts that the semi flexible panels are better now but I still read about early failures of flexible panels.

What am I not understanding is how a 100W panel can keep your battery from dropping below 80% SOC, assuming the power consumption values above are close to correct (and perhaps they are not - but I would then like to understand what the power consumption actually is) in any situation other than parked with no shade and no clouds in late spring through early fall when the sun is still high in the sky.

This question is posed mainly so people who are thinking about their setup can better understand the details.

I think it is better to have plenty of power with some margin (for the successive cloudy days) than not enough. If you add additional devices to your camper (or camping), such as electric bikes, a drone, a computer, etc, that require power, there will be power available without having to upgrade the solar charging system (again).
 
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It was my understanding that partial shade on a panel can cause it's output to be drastically reduced or go to zero. That is why I installed 2 100W panels wired in parallel on different areas of the roof. Could this be a problem with a single large panel? Let the experts educate me.
 
I don't understand how your battery stays above 80% SOC from a 100 W solar panel without having a separate source of recharging.

Everything I have read about 12 v refrigerators leads me to believe that the 24 hour power consumption is 30Ah - 40Ah (depending on manufacturer and model) in 70 - 80 degree weather and higher in hotter weather.

Looking at some manufacturer specs for electric blankets shows they draw 3 - 4 amps per hour. So 3 hours would be 9Ah to 12Ah.

Not counting the power to run the fan from the heater, roof vent fans, internal lights, periodic use of a water pump (if you have one), recharging phones and other devices. It seems your daily consumption would roughly be between 40Ah and 50Ah a day.

With clear skies and a well pointed panel a 100w solar panel will produce 30Ah - maybe 35Ah a day at best.

Seems to me even in ideal conditions the panel would be barely recharging the battery if not slightly falling behind everyday.

Consumption of around 40Ah per day is consistent with our experience in our camper on late spring through early fall use. We need more power in early spring, late fall and Winter. We originally had a 100W panel. When we experienced cloudy days or rainy days the panel could not recharge the battery every day and it got lower and lower.

I looked at adding a second panel and found that a single 300W - 350W panel was marginally more expensive than another 100 W panel and that the weight of the single 350W panel was less that two 200W panels.

I am talking about rigid panels. I am not aware of any semi-flexible panels over 270 W. Also, a good quality 200W semi flexible panel is close to the price of a 350W rigid panel.

I made the conversion several years ago when semi-flexible panels were frequently failing within 12 - 18 months of purchase so I decided to stay with a much more reliable rigid panel. I have read accounts that the semi flexible panels are better now but I still read about early failures of flexible panels.

What am I not understanding is how a 100W panel can keep your battery from dropping below 80% SOC, assuming the power consumption values above are close to correct (and perhaps they are not - but I would then like to understand what the power consumption actually is) in any situation other than parked with no shade and no clouds in late spring through early fall when the sun is still high in the sky.

This question is posed mainly so people who are thinking about their setup can better understand the details.

I think it is better to have plenty of power with some margin (for the successive cloudy days) than not enough. If you add additional devices to your camper (or camping), such as electric bikes, a drone, a computer, etc, that require power, there will be power available without having to upgrade the solar charging system (again).
Good questions, ckent. Clearly we are on one side of the bell curve for power usage. My post didn't answer the original poster's question, so sorry for the thread drift. (I'd probably get just one panel, might as well get as much wattage as you can afford).

Our fridge usage is based on almost 500 nights out, mostly Oct-May but a lot in southern California deserts. I haven't calculated amp-hour usage for it. It seems to turn on a lot. Some of the days when out hiking it was really warm. A few weeks ago it got up to 82F, but it was sunny. Our solar easily kept up while wandering all day. Perhaps we spend more time outside the camper with just the fridge using power than other folks? Hard to say -- everyone is different. Also we have the small 65 liter fridge, usually set at 1.5 or 2.

We don't have some of the other gadgets you mention except we sometimes use a laptop, have two tablets and 3-4 phones (don't ask why so many phones!), a rarely used vent fan. The electric blankie uses about 3.5 amps, close to what you mentioned. We don't anticipate an electric bike

On cloudy but warmer days stuck in the camper, I think we use about 25-35 Ah per day... that's a guess. Probably similar for colder days due to heat. We've had to hunker down in bad weather and I'm kinda recalling those numbers. It's really important to know what you use. We'd have to drive after about 3 days stuck inside.

We use a flex panel because I don't want to drill holes in the roof. The aero excuse isn't a very strong one, admittedly. Before we had a 90W suitcase panel that kept up ok, but it was 22 lbs. The 100W flex panel is only 5 lbs and so thin that we put it on the bed when travelling. Not for everybody though because in camp we have to put it on the roof or windshield (or the ground propped against something), tie it down, and reverse the process when breaking camp.

On aero, I'd like to design a fairing but haven't gotten the energy to figure it out. I think it's a tough 3D problem so I'd want to use 3D CFD software. Our windshield is pretty close to the front of the camper, so that aero transition will be tough to solve. I've read about others who've made flat fairings haven't improved gas mileage, but have reduced noise and bug squishes. I'd want to do it right, but too many other projects seem to have priority. But it'd be fun excuse to use my son-in-law's 3D printer. I wish I still had access to 3D modeling, but retired from that stuff a decade ago. However, I tried 2D modelling a few years ago.
 
It was my understanding that partial shade on a panel can cause it's output to be drastically reduced or go to zero. That is why I installed 2 100W panels wired in parallel on different areas of the roof. Could this be a problem with a single large panel? Let the experts educate me.
Short answer = Yes. Long answer, it depends on how many diodes are in the panel(s) and perhaps other factors too.
 
I offer an alternate opinion as I recently upgraded to two 100W roof panels (in parallel) and a 3rd 100W portable panel after the original, less than 5 year old, roof mounted panel died.
Rational: From my experience, and as @ckent323 points out, flexible panels are prone to fail, and I rather not lose all electrical generating capability if/when the next one fails. In my opinion, having the redundancy of two smaller panels is worth the small increase weight over a single larger panel. I should state I'm not wired for truck charging so the redundancy may be less critical if the truck alternator is used as a backup charging source.

The remote panel? Not so much for redundancy but gives me the ability to park in shady spot on a hot day and keep the portable out in full sun.

In other words, my roof mounted panels are there to collect power while driving and the remote becomes the predominant charging method once parked.
 
With ever improving ETFE exteriors & integrated cellular bus bars, I’m going to give flex a try. The life span 7 years ago was disappointing but improved on my 2nd set, which were a step up from my initial cheap commodity panels. Being w/o a camper for 2 years, I’m hopeful the current flex panel tech will impress. The roof weight for me is a factor vs the increased longevity of glass. Almost sure I will run 2 separate roof panels with one dedicated to my fridge housed in the truck. The pricing is friendlier, but with tariffs?, quien sabe?
All the discussion above ruminates with me. I have a semi recent portable & prob will add another.
 
Desertdog,

The 360W panel on the roof of our camper, with cables and mounting hardware is about 42 pounds. The panel is now almost 4 years old and is working as new. The camper and solar panel are outside 365 days a year and the panel has survived a trip to Alaska as well as sun, rain and moderate size hail. It provides all of our electrical power. Since installing it I have not needed to have the camper connected to the truck charging system. The battery bank is two Lifeline deep cycle 12v 220Ah AGMs. The batteries are 6 years old and working as new (as far as I can tell). They have had 2 cycles on them and only twice have been discharged below 75%.

We have a Norcold N300 3-way refrigerator and are contemplating going to a 12v (looking at Isotherm, Dometic and Vitrifrigo models of comparable size). I think the Vitrifrigo has a slightly larger freezer compartment, We have plenty of excess power production (I planned to change over to a 12v fridge at some point when I sized the solar panel) so not worried about the change.

 
Another weight data point: my two Renogy rigid 200 watt panels total 52 lbs. I increased the struts on my Grandby from 30 lbs to 40 lbs, which is about right. The rears could have stayed at 30 lbs and been fine. I have to pull the rears down about halfway before it wants to drop on its own, but it’s easy to stand on the bumper and pull, and that gives me a chance to make sure it folds properly.
 
CK, your reasons above had me thinking glass this time. But 42lbs gives me pause, let alone Jon’s 52lbs. At 69, with 70 on the horizon this year, that much weight on roof allocated to panels this time around would be weight excessive. With my new Raven installed yesterday, I’d like to add a few items on the roof (with so much less space than my previous Grandby) utilizing added accessory weight in lieu of solar panels. (recovery, etc.)
 
Stokeme

I will be 72 in a few months. The Solar panel is mounted on the roof between the front and rear vents on our 2007 FWC Keystone. The weight is slightly aft of the middle of the roof. Lifting the roof with the over cab bed extension slid in is not a problem for me.

However, we normally travel with the over cab bed pulled out and with the over cab bed pulled out the effort to lift the roof is more than I want to lift (although I can) so I use an On-Stage model SS8800B crank up speaker stand to lift the front when the bed is pulled out. Lifting the back is no problem for me. However, Wendie can use the speaker stand to lift or lower either the front or the rear.

We open the door and reverse the ceiling fan to pull in air (very slightly pressurize the interior of the camper) when lifting the roof. Similarly, the fan and door can also be used to control closing the roof.

I have carried kayaks on the rood in the past and the only way I can raise and lower the roof when they are on is to use the speaker stand.

Jon R's comment caused me to recall that have 2 interior lift struts at the point where the over cab bed starts. We do not have rear lift struts on our camper. I changed the struts to 40 pound struts several years ago. They seem to only last a couple of years before the seals leak and they are not helping much so that is something we all should keep an eye out for on our campers.

On my list of upgrades is a 12v linear actuator to use instead of the speaker stand. I think it is probably a better solution for lifting and lowering and would work even without the lift struts.

 
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If roof weight is a big concern, an approach that can work for some people, depending on how long they like to camp remotely in one spot without running the engine, is to not do solar at all, and instead invest in a large battery capacity and the maximum sized truck charger your alternator can supply.

I can easily go four to five nights on my 200 ah battery in my Grandby. My 30 amp charger provides a day’s worth of charging in less than 90 minutes of driving. A 50 amp charger would be proportionally faster.

I use solar as my primary charging source, and usually have my truck charger turned off. However, I would be fine without solar on nearly all the trips we do. Heck, 1/2 the trips are long weekends and I really don’t need any charging if I start with a fully charged battery.
 

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