Has anyone added roof-mount solar to Coachmen Prism?

[FollowTheSun]

Wife and I are about to begin new ventures as we ready to purchase a class-c Sprinter, lease our home, and drive into a year of travel as we search for a new homestead. While we feel confident about our class-c MB Sprinter decision, we have not yet decided which make. We are persuaded toward a 2016/17 single slide unit with the diner, closet, and queen bed on the port side. However, I wish to add a few things to the motorhome which I believe will greatly enhance our boondocking comfort. While most of the things I wish to add are quiet simple, three items concern me because of available space or necessary coach modification, these are: 1) 300 watts roof-mount photo-voltaic, 2) whole-house reverse osmosis for freshwater, and 3) shore AC power surge protection.

In this thread, I would like to focus on the photo-voltaic solar panels, and leave the other two topics to another thread. I have already calculated my average daily power consumption and have concluded that 300 watts with a MPPT controller will generally satisfy my daily energy recharge rate on a weekly schedule (already compensated for a flat panel roof-mount with seasonal variation). I am, however, concerned about available roof real estate for two solar panels on a class-c Sprinters. Has anyone here accomplished such installations with ideas and experience about how I should proceed?

[Rich.M]

There is a lot of information already in older strings. Search MBS, Solera and Forester strings for "solar" to get up to speed. I also suggest the Jack Mayer website to understand the practical electrical and mounting details. 300 watts flat mount with mppt is about right to boondocks with MBS. We have 400 watt on pwm and no shortage of power.

[FollowTheSun]

Originally Posted by Rich.M

There is a lot of information already in older strings. Search MBS, Solera and Forester strings for "solar" to get up to speed. I also suggest the Jack Mayer website to understand the practical electrical and mounting details. 300 watts flat mount with mppt is about right to boondocks with MBS. We have 400 watt on pwm and no shortage of power.

Greetings Rich.M ... thanks for the advice. Also you have indirectly answered part of my concern by mentioning you have 400 watts on your roof. How many panels did you install?

[Rich.M]

We have 4 * 100 watt Renogy eclipse panels. They are small in size for their output, high amps ( nearly 6 amps) at a lower voltage of 17.7 made them a better match for pwm controller. 4 panels spreads out well on the roof to minimize shade problems. We have frequently dry camped and had more than enough power. 300 watts would likely be enough if not too many cloudy days.

[Rich.M]

Roof landscape also crowded with wifi ranger and we boost 4gm cell booster on metal ground plane. The Renogy panels work well and are sturdy. We just went thru a hail storm with dime to quarter sized hail without panel damage. Our hengs vent covers have bullet sized holes and cracks after the storm. Duct taped for now as we are 15 days into a 4 week trip.

[FollowTheSun]

Originally Posted by Rich.M

Roof landscape also crowded with wifi ranger and we boost 4gm cell booster on metal ground plane. The Renogy panels work well and are sturdy. We just went thru a hail storm with dime to quarter sized hail without panel damage. Our hengs vent covers have bullet sized holes and cracks after the storm. Duct taped for now as we are 15 days into a 4 week trip.

Rich.M thanks for the photograph ... it says a great deal. It is good to hear that the panels survived the hail. Sorry to hear about your other damage. Interesting, I too am planning to add wifi and cell boosters. I am actually hoping to use one of solar panel as a counterpoise for the cell-booster antenna, and to also shield between the exterior and interior antenna. Since I plan to experiment with an exterior omni-directional and and interior directional, may need a shield to prevent signal feedback. Have you done any experimentation using a solar panel for your ground plane/counterpoise? This scheme, if I can make it work, will allow me to use the booster while in motion and get rid of the so called “candy-bar” antenna which terrible limits the use of your cellphone.
I am also hoping to install the wifi cable such that I can exchange between a whip and a yagi depending on need. I think a yagi with the cell booster is probably unless since calls transmitted between any tower further than 22 miles away will create packet delays greater the 250 microseconds which will begin to drop calls, but I'm not sure about that … haven't kept up on cellphone systems. Beside, a yagi is only useful if parked.

[Rich.M]

I chose to place my booster antenna on a round 3 inch high, 9 inch diameter cake pan painted to match roof as ground plane. This met the criteria for 1/4 wavelength in the cell freq for Verizon lte. 3 inches high was needed to get above the panels. The cake pan is round and seems to maintain the omni directional antenna well in use. I mounted far enough from panel to prevent shading. Even a small shadow may drop panel output. These coaches are small and the cell boosters have internal automatic anti feedback circuits. I went with the candy Bar internal ant but used a low loss cable to run it to the passenger seat visor shelf. Now anyone sitting in passenger seat can call when driving or stopped with boost. If I need to hot spot wifi then we just put iPhone on visor shelf. The coach metal roof keeps cell signal leakage low for max boost at roof ant. It is working well for us. Too complicated to try and shield all areas of such a small coach and I wanted to keep internal ant hidden.

[dukeboone]

I have two 160w panels flat mounted on my roof. In some circumstances the A/C shades one of the panels, which is unfortunate however the overall performance for our needs has been superb. I ran both fans all day, used the interior lighting as much as needed, left portable devices plugged into USB ports to charge and even used the bedroom TV to watch a feature length movie. But the time I went to bed the solar controller was reporting that our capacity was at 85%. By mid morning we were back to 100%.

My controller is a BlueSky 2512ix MPPT controller and I have the BlueSky IPNPro Remote with a battery temp lead and shunt. I also used 6 AWG cable. It's a great system and the remote display gives me an enormous amount of great data.

[dukeboone]

[FollowTheSun]

Greetings dukeboone, thanks for posting those photograph, it is a very clean install. I think a few shadows are unavoidable, as are gray skies. All you can really do is compensate by installing a bit more solar, and try to reduce other losses. I like that you are using 6awg wire versus 8awg. At 320 watts max load the IR drop for 8awg would have been about .12 volt per 10 feet wire run; 6awg is near half at .07 volts per 10 feet. At full load 8awg is producing about 2.2 watts loss per 10 feet; whereas 6awg is about 1.4 watt per 10 feet. While the difference seems insignificant, so also was the cost and labor difference. When designing a system with so many uncontrollable variable, it is good to reduce controllable losses at every practical corner. Given your total wire length is probably two conductors run about 20 feet (40 feet of wire from panel to battery with controller in middle): your 6awg choice is conserving about 25 to 30 watts per day. (forgive me ... I carry an engineering curse from my first career. I can't focus on an entire subject for long, but I can torture an insignificant detail to death.)

[I Simpson]

Originally Posted by FollowTheSun

Wife and I are about to begin new ventures as we ready to purchase a class-c Sprinter, lease our home, and drive into a year of travel as we search for a new homestead. While we feel confident about our class-c MB Sprinter decision, we have not yet decided which make. We are persuaded toward a 2016/17 single slide unit with the diner, closet, and queen bed on the port side. However, I wish to add a few things to the motorhome which I believe will greatly enhance our boondocking comfort. While most of the things I wish to add are quiet simple, three items concern me because of available space or necessary coach modification, these are: 1) 300 watts roof-mount photo-voltaic, 2) whole-house reverse osmosis for freshwater, and 3) shore AC power surge protection.

In this thread, I would like to focus on the photo-voltaic solar panels, and leave the other two topics to another thread. I have already calculated my average daily power consumption and have concluded that 300 watts with a MPPT controller will generally satisfy my daily energy recharge rate on a weekly schedule (already compensated for a flat panel roof-mount with seasonal variation). I am, however, concerned about available roof real estate for two solar panels on a class-c Sprinters. Has anyone here accomplished such installations with ideas and experience about how I should proceed?

We haven't only because we don't lije to put holes in rhe roof. The one on my Lance didn't belp noticeably.

[FollowTheSun]

Originally Posted by I Simpson

We haven't only because we don't lije to put holes in rhe roof. The one on my Lance didn't belp noticeably.

Greetings I Simpson. Yeah, the idea of adding a few holes also concerns me. But yet, the manufacturer already put a lot of holes in the roof for various vents and AC. Those holes seem quite secure, although I suppose periodic inspection is wise. It seems, at least to my inexperienced neophyte mind, that we should also be able treat any new holes with the same technique the manufacturer used … but this idea also seems like I might be poking the dragon, so-to-speak.
I have watched several videos where folks simply glue the mounting brackets to the top of the roof membrane. Although they seem to use a suitable high-strength adhesive, this technique, without some kind of mechanical attachment (screws) into roof struts or some other framing, causes me serious concern.

[Sandiegodoug]

I bought the flexible 100 w panels. They are frameless . I attached to roof using industrial strength Velcro all around. Hug the roof tightly and I think I would need a crow bar to remove

[FollowTheSun]

Originally Posted by Sandiegodoug

I bought the flexible 100 w panels. They are frameless . I attached to roof using industrial strength Velcro all around. Hug the roof tightly and I think I would need a crow bar to remove

That is an interesting idea! It gets rid of a lot weight and wind resistance. Have you notice an thermal issues with panel performance or with causing roof hot-spots?

[Sandiegodoug]

No
Panels work great. Very flat on roof. They are 100w panels and I could easily fit 2 more, but I find these work fine. (I have 2) mine are renology panels but there are others. Smaller than framed panels. I didn't want to drill my roof . The 2 inch industrial Velcro all the way around was probably overkill but didn't want to take a chance of loosing them, plus keeps wind from getting underneath panels.

[hkreck]

Where did some of you get your solar system from? Model #'s and the like?

[Sandiegodoug]

I bought mine from renology
100w flex able panels
They sold me all the parts to
Connect to my controller
I bought a mppt 30 amp controller
From Amazon , although better ones available , it was cheap and seems to work well. I also got all the wire and connectors from renology . They are the ones that recommended the 2 inch industrial strength Velcro to attach the panels to the roof. Very easy to install

[MarsMan]

I have a 2015 Prism. added 250 watt panel. Works great (over a year). Also a Trik-L-Charger to allow the solar to keep my MBS battery charged.

FYI- we decided against the slide with the bed in it. We are often in areas we may not be able to extend the slide... sleeping can become a problem. We have the corner queen and the slide (with the closet/dinette in it). Can fully operate without slide out... However, way more oom when it is

[FollowTheSun]

Originally Posted by MarsMan

I have a 2015 Prism. added 250 watt panel. Works great (over a year). Also a Trik-L-Charger to allow the solar to keep my MBS battery charged.

FYI- we decided against the slide with the bed in it. We are often in areas we may not be able to extend the slide... sleeping can become a problem. We have the corner queen and the slide (with the closet/dinette in it). Can fully operate without slide out... However, way more oom when it is

Greetings MarsMan ... We just got the Prism 2150LE and completed a 3-week 3,600 mile shakedown. We finally decided on the corner-bed/single slide for the same reasons you stated. Roof space is very limited so it seems I will need to settle on 200 watts total solar. As we learned during our shakedown, 200-watt supply should serve us well as our electrical use seems much than originally estimated.
By the way ... how did you attach your solar panels to your roof?

[MarsMan]

Originally Posted by FollowTheSun

Greetings MarsMan ... We just got the Prism 2150LE and completed a 3-week 3,600 mile shakedown. We finally decided on the corner-bed/single slide for the same reasons you stated. Roof space is very limited so it seems I will need to settle on 200 watts total solar. As we learned during our shakedown, 200-watt supply should serve us well as our electrical use seems much than originally estimated.
By the way ... how did you attach your solar panels to your roof?

Nice choice... I stand corrected. My panel is 200W and not 250W. I forgot I wanted a 250 and could not find the real estate to install. I contatcted Coachmen and asked for the roof structure drawings for my 24J. I was able to use selftapping screws to hold down one edge of the panel. I also dicored the crap out of it. The other edge I used expanding screwed (used in drywall and again dicored the crap out of it. On the leading edge I placed a deflector (small plastic tube) to keep wind from flowing under the panel and causing some lift.30,000 miles and several days in high headwinds and higher speed, all is good. I ran the wire down thru the fridge vent and under my kitchen counter. Put a cut off switch in line between the panel and the controller. The controller was mounted near my step where my batteries are located. Ran heavy gauge wire to the batteries. Also installed Trik--L- Start to keep things charged on the Benz side when she is not in use or boon docking/parked for extended time. Check your Coach batteries monthly to make sure acid not cooking off. After 1 year of continous use, levels remain at the proper levels. PM me if you have other questions.... I may not be able to answer all. I have had extensive experience with my Prism and its "quirks"