Lets Talk Solar

CanuckRV · 07-14-2022, 09:58 AM

I have a '97 Roadtrek Popular 190. Currently, I have 2 100 amp hour Renergy LiFePo4 batteries, being charged either by a Renergy 40 B to B charger or by shore power.
My wife and I usually drive enough daily to keep the batteries charged but we have a trip coming up where we won't be doing so much driving and no shore power and would like to be able to top up the batteries so I'm looking at solar.

We have basically two systems 1) permanently mounted to the roof 2) portable "suitcase" both have advantages with a permanently mounted system we also have two choices ridged and flexible.

If I go permanently mounted I'm leaning towards flexible to conform to the curved roof and reduce drag.

I like the idea of the suitcase but if we are parked we are probably off on a hike or some such thing and worry about the pannels also hiking off. Also, there is not a lot of storage space in a Roadtrek. But not having to park in the sun also has its benefits.

Please tell me the good and bad of all the options.
Thanks

@Michael · 07-14-2022, 02:32 PM

I have both permanent flexible and portable flexible panels and can use both at once.

You've summarized the pros and cons quite well.

Rigid panels will have higher output per area and will last longer than flexible. Suitcase type panels will be the most portable but have the lowest output per area and highest cost per watt.

Depending on where you are camped, leaving panels unsecured while you are away from camp might be an issue. They also like to get blown over by the wind.

Running the engine and charging with your B2B might also be an option.

Have you an idea how much power you are using per day? Do you have an inverter, compressor fridge or other gizmos that use lots of current?

hbn7hj · 07-14-2022, 03:24 PM

What happened to the generator?

mkguitar · 07-14-2022, 03:43 PM

Quote:

Originally Posted by CanuckRV

...not having to park in the sun also has its benefits.

This is prime for me
and not just because I live in Arizona- we always try to park in the shade

mike

Davydd · 07-14-2022, 05:28 PM

I had 460 watts of solar panels on my roof on my previous Class B. I quickly realized that with 800ah of lithium batteries and a second under hood alternator that the solar panels were not needed. 15 minutes of running a second alternator could put more charge in the batteries than those solar panels in a day.

I also tend to mostly camp and tour in fall, winter, spring where the sun angles suck and the days are short and in the summer mostly at home in the Minnesota and upper midwest north woods (trees

).

So my current Class B has no solar panels whatsoever but still have the high capacity lithium ion batteries and the second alternator.

If you need or want to store outside under the sun without shore power for long term storage then solar panels can have a use. Under normal circumstances in camping driving is the distinct advantage of a Class B over any other RVs and can contribute more charge than any amount of solar panels you can get on top of a Class B.

In answer to the question. If you are parked with no shore power and in a remote situation where you might be hiking away from you Class B, I would be leery of putting suitcase solar panels out as you mentioned. If you think you can place them in the sun away from your Class B under the trees, you might not be able to do so or your panels may be set away from your Class B and be even more vulnerable. If you think you need solar put it on the roof with permanent mounting.

With my first two Class Bs and 200ah of AGM batteries and no under hood generator I also had no solar panels. If driving every day just a bit like going to trailheads I had no problems in being off grid. If an upcoming trip is not a norm buying and installing solar panels for it may not be cost effective when other creative organization and planning will do. I would think you could park at a minimum of two days off grid without solar panels without driving and minimal use with 200ah of battery.

GallenH · 07-15-2022, 09:24 PM

I have used a suitcase solar panel extensively in the 5 yrs since I've bought it. Mine is a 1997 PW with 100AH battery. I wired an outlet in a box going to the battery and fastened the box under the rear bumper. It has a rubber cover.

Setup is easy. Connect panel to outlet with plug after unfolding. Put it in a place that faces current sun. Change it's position in the afternoon to track sun.

In the campsite, it's chained to the hitch and then to the panel with padlocks. If I leave the site to go to a trailhead, it only takes a few minutes to break that down and put it in the RV. I've even left it at the site, chained to a tree or picnic table.

I've always been able to get back to 100% charge within a few hours, but.....a lot of the equation is the size of the bank and how power is used. I don't have a compressor fridge, so my power use is very low so the panel has to problem restoring what I've used. If you were a big power user with big battery banks to recharge a suitcase panel might not be the best option.

SteveJ · 07-16-2022, 05:09 AM

We are in our 7th year of several months per year of dispersed/dry camping. We have yet to lose our hard framed portable suitcase panels. We have a 25' vinyl coated wire cable and a couple of small cheap padlocks. We never pick them up when we leave the site, sometimes all day.

Each set of panels(120 watts each set of two) was re-wired to be in series to provide more efficient charging through the Victron MPPT charge controller. One set has a 50' 12 gauge cord that hooks into a connector on the RV. The second pair of panels hooks up in parallel with the first. We also carry a 25' extension cord that is rarely needed.

Set up takes about 5 minutes, stowing takes a bit more time at about 10 minutes +/-.

With our latest RV the daily AH budget has creeped up to 25 to maybe 80 AHs/day. Most days we do accomplish float charging in our two LA batteries unless it is really dark and gloomy.

booster · 07-16-2022, 10:56 AM

Quote:

Originally Posted by SteveJ

We are in our 7th year of several months per year of dispersed/dry camping. We have yet to lose our hard framed portable suitcase panels. We have a 25' vinyl coated wire cable and a couple of small cheap padlocks. We never pick them up when we leave the site, sometimes all day.

Each set of panels(120 watts each set of two) was re-wired to be in series to provide more efficient charging through the Victron MPPT charge controller. One set has a 50' 12 gauge cord that hooks into a connector on the RV. The second pair of panels hooks up in parallel with the first. We also carry a 25' extension cord that is rarely needed.

Set up takes about 5 minutes, stowing takes a bit more time at about 10 minutes +/-.

With our latest RV the daily AH budget has creeped up to 25 to maybe 80 AHs/day. Most days we do accomplish float charging in our two LA batteries unless it is really dark and gloomy.

100' of 12ga (out and back) total is going to give you over 1.25v of drop and cost you quite a bit of capacity as it is nearly 10% drop. How much can you harvest in a day?

Blueboy1 · 07-17-2022, 12:27 AM

Hi, send me a private message and I will show you my 250 watts roof mounted solar panels on my 1996 Dodge PW. No need to be flexible ! Have a nice day all

Winston · 07-19-2022, 12:20 AM

Quote:

Originally Posted by Davydd

I had 460 watts of solar panels on my roof on my previous Class B. I quickly realized that with 800ah of lithium batteries and a second under hood alternator that the solar panels were not needed.

Davydd, we have heard this argument frequently. But having parked 10 days straight at the Oshkosh Airshow last year without shore power and without moving the vehicle an inch, has taught us the contrary.

GaryBIS · 07-22-2022, 04:09 PM

Hi,
Another factor for roof mounted solar panels is that they increase aero drag and decrease MPG. Probably near negligible for flexible panels mounted right to the roof, but can be 2+ MPG for the full roof rack mounts.
An MPG test I did on this...
https://www.buildagreenrv.com/mpg-pe...n-camper-vans/

Gary

booster · 07-22-2022, 06:56 PM

Quote:

Originally Posted by GaryBIS

Hi,
Another factor for roof mounted solar panels is that they increase aero drag and decrease MPG. Probably near negligible for flexible panels mounted right to the roof, but can be 2+ MPG for the full roof rack mounts.
An MPG test I did on this...
https://www.buildagreenrv.com/mpg-pe...n-camper-vans/

Gary

I don't understand the simulated roof rack. It is an aerodynamic nightmare, I think. Leading spoiler/deflector an then a recess, then flat area with other recesses, etc. How bad would indicated by the 4% frontal giving 10% in mpg decrease

With anything like solar panels, I want the long dimensions parallel to the airflow and consistent. Steps and bumps are not a good idea.

We have 3 100 watt panels on the rood of our 07 Chevy Roadtrek 190 and have found there to be at most a minimal .2-.3 mpg increase but other times we don't see any change over the same trips. Our mpg over thousands of miles, with and without the solar has been very consistent.

Our panels are off the roof for cooling and to let some air under them to help reduce the negative pocket you get behind them. I don't care for putting a leading edge deflector on unless the panels are not parallel to the airflow.

GallenH · 07-22-2022, 07:24 PM

Thanks for the interesting test. The pictures appear to show a panel with a traditional mount, not a flex panel. Is that correct? If so, was it that panel that gave you the 0.1 increase in MPG?

Other discussions on this site have indicated that flex panels mounted directly on the roof increase heat inside and promote a "hotter running" solar panel which decreases it's effectiveness. Not sure about all of that but it's worth considering for someone thinking about installing panels; in addition to the fact that they degrade faster than traditional ones.

Excellent work. Must have taken a while to do and definitely worthwhile to the rest of us.

dmb496 · 07-22-2022, 09:46 PM

We own a 2020 Galleria built on a 2019 Sprinter 3500 dual tired chassis. The vehicle had 3 - 100 watt flex solar panels that were installed by Coachmen.

This spring I decided to remove the 3 flex panels. I replaced them with 4 Renogy 100 watt hard panels. The surface of the new panels are 3" above the Sprinter roof. I also installed a small air deflector on the front.

The old flex panels were glued directly to the roof. They were very good at heat-soaking and that heat was transferred into the Sprinter's roof. I'm glad they are gone.

The new panels provide a lot of shade to the roof and transmit no heat.

We have traveled 3,800 miles this season since installing the hard panels. Our fuel mileage this season is identical to last season when we still had the flex panels. No increase, no decrease.

GeorgeRa · 07-22-2022, 09:51 PM

I have also 300W - 3 100W panels setup attached to roof rails and practically there was no difference in fuel consumption, but I don’t have a roof rack.

CanuckRV · 07-24-2022, 02:27 PM

Well, we just got back from our trip and have no issue with replenishing the batteries even with just short trips. The shortest was only 4 hours and 1 and a half was on the Ferry to PEI (luckily 2 days before the fire) and were at 100% at the end of the trip. With our Energy usage, we can do about 3 days on our 200amp hr storage capiacity.

Boxster1971 · 07-24-2022, 05:08 PM

Quote:

Originally Posted by CanuckRV

Well, we just got back from our trip and have no issue with replenishing the batteries even with just short trips. The shortest was only 4 hours and 1 and a half was on the Ferry to PEI (luckily 2 days before the fire) and were at 100% at the end of the trip. With our Energy usage, we can do about 3 days on our 200amp hr storage capiacity.

For those that are not aware of the Prince Edward Island ferry fire last Friday.

https://globalnews.ca/news/9008755/pei-ns-ferry-fire/

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