Which solar panel would you choose for camper rooftop

[Wo_ody]

So its May 2014. Which specific solar panel would you choose to roof mount on your motor-home? When making a decision...are all panels aerodynamically suitable to withstand 85mph? Looking at installing a 600 amp battery bank and do not have unlimited roof space. Thanks for your input.

[Almot]

mena661 wrote:

Almot wrote:
I don't have 600 AH bank, but if I had, I could live a week without any solar at all, keeping rig warm and with as many hot meals and coffees a day as I wish. When there is more than one person in the rig, things are more difficult to control though.

We could do this back when we had the 5th wheel as the standby draws were an order of magnitude lower.

Standby draws can not be high, I don't know how many devices one must have to exceed 8-9 AH standby. If you could live off 45 AH a day including 1A standby, you could - with some effort - make it today on 45 AH including 8 AH standby.

But if you mean those real "standby" like radio, TV and LP sensor, and also idling current of always-on inverter (not Off current but no-load current), and semi-permanently running LP fridge circuit, then it will be more.

[mena661]

Almot wrote:
I don't have 600 AH bank, but if I had, I could live a week without any solar at all, keeping rig warm and with as many hot meals and coffees a day as I wish. When there is more than one person in the rig, things are more difficult to control though.

We could do this back when we had the 5th wheel as the standby draws were an order of magnitude lower.

[Almot]

JiminDenver wrote:

We used our 230w 24v panel as a portable last year and boy was it nice. The first trip we tried to use as much power as we could, the only time the batteries voltage dropped at all was at night. The next trip I left it flat on some logs for a week to simulate it mounted. Again we never ran out of power even though it clouded up by noon daily. The last trip was cold, cloudy and rainy most of the time. We were inside running the furnace more and watching DVDs to drown out the neighbors Honda 3000. Even though the output was minimal, it kept us off the generator.

What I said. Minimum solar size depends more on the user than on the weather. 230W portable is tilted, so this is roughly equivalent to 390W flat in winter, in summer tilt is less important.

Handy Bob - sorry, post editor doesn't work: http://handybobsolar.wordpress.com/about/
is living fulltime off 345W solar, and it does snow there. His panels are tilted so this is roughly equivalent to flat 590W in winter. Mind you, the guy is living fulltime, with power tools and all.

There are ways to reduce energy consumption without sacrificing a comfort, but people are usually reluctant to learn. I don't have 600 AH bank, but if I had, I could live a week without any solar at all, keeping rig warm and with as many hot meals and coffees a day as I wish. When there is more than one person in the rig, things are more difficult to control though.

[Almot]

ops - double post.

[Almot]

mpierce wrote:
"Most use 3M tape" to mount the panels. Wrong. Very few just use tape. Tape can ONLY be used on solid roofs, not rubber. I would hazard well over 90% use screws.

Yes. Rubber coated plywood is different from aluminum or fiberglass surface. Members here used 3M tape on fiberglass roofs, some used both 3M and deck screws. I also recall a report of one so-called "professional" in Quartzite that used 3M on rubber coated roof without screws, and example of unsafe install.

[JiminDenver]

rctour wrote:
Solar is a great topic and I think we motorhomers are just at the beginning of a trend to use them. I just started my journey in solar.

An alternative? I did a little research and think I came up with a good starter package; 2-250W 24v mono panels, breakers, breaker box, 60amp MPPT controller, monitor, heavy wire, brackets, all top quality stuff for about $1,300, that's before any delivery costs.

Then I decided for me a better alternative was a 200W mono folding portable panel with built in controller and battery clips for $475 including delivery. Trees will be much less an issue and more watt for the buck!

I can afford to experiment with $475 (I can sell it pretty quickly if things change).

My knowledge is minimal as is my watt needs, I think? I want to subsidize my power needs, not try and fa-fill them. It's an experiment, we'll see how it works out.

You can get a 200w folding portable from Eco-worthy or windynation for $300 shipped.

We used our 230w 24v panel as a portable last year and boy was it nice. The first trip we tried to use as much power as we could, the only time the batteries voltage dropped at all was at night. The next trip I left it flat on some logs for a week to simulate it mounted. Again we never ran out of power even though it clouded up by noon daily. The last trip was cold, cloudy and rainy most of the time. We were inside running the furnace more and watching DVDs to drown out the neighbors Honda 3000. Even though the output was minimal, it kept us off the generator.

[Shadow_Catcher]

One thing to remember is that wind speed is not road speed. We hit 40+ MPH head winds for days it seemed like two years ago when we went to California. Add that to vehicle speed of 65 to 70 plus wind gusts from passing semis going the other direction...
We have a single 66 cell high voltage panel (big) that has six ABS plastic mounts held on with 3M VHB tape to a Filon roof. I did this after calling #M and talking to an engineer who told me how much contact area I needed and the surface prep necessary. If I were to do it again I might use 2X2" aluminum angle. You do NOT want to completely enclose the bottom of the panel to allow for cooling.

[mpierce]

"Most use 3M tape" to mount the panels. Wrong. Very few just use tape. Tape can ONLY be used on solid roofs, not rubber. I would hazard well over 90% use screws.

[rctour]

Solar is a great topic and I think we motorhomers are just at the beginning of a trend to use them. I just started my journey in solar.

An alternative? I did a little research and think I came up with a good starter package; 2-250W 24v mono panels, breakers, breaker box, 60amp MPPT controller, monitor, heavy wire, brackets, all top quality stuff for about $1,300, that's before any delivery costs.

Then I decided for me a better alternative was a 200W mono folding portable panel with built in controller and battery clips for $475 including delivery. Trees will be much less an issue and more watt for the buck!

I can afford to experiment with $475 (I can sell it pretty quickly if things change).

My knowledge is minimal as is my watt needs, I think? I want to subsidize my power needs, not try and fa-fill them. It's an experiment, we'll see how it works out.

[Almot]

Wo.ody - plenty of good advice here, but it looks like you need to read up more, before trying to make any choices. No offense, but there is no answer to your question "which panel".

Like Jim said - install as much solar as possible. There is a "recommended" amount of solar 600W for 600 AH bank, but you won't regret if you install more. Depending on your energy habits and the area where you camp, you may need anywhere from 400 to 1,000W to cover all you needs with solar except for maybe airconditioner. Some people can make it on 400W, and some need +1,000W even in dry and sunny locations. The only thing that is difficult to run off battery and solar is airconditioner, it requires too much AH and high current.

Type and size of controller will become clear after you'll have decided on total panels wattage and voltage.

Leaving aside Unisolar amorphous flexible panels, all panels are pretty much the same in terms of size per given wattage, and all have about 1.5" thick frame with rectangular profile. If you want to be sure it won't be ripped off the roof at 85 mph, you need to use adequate size and type of mounting brackets, this has nothing to do with panel choice. Brackets are usually home-made, they keep the panel at 2"-3" above the roof - necessary for heat dissipation, and at about 4 degrees angle to the sides or to the rear or front - this is necessary to drain rain water. Off the shelf brackets are rarely good, and for panels 120W and larger I wouldn’t use them at all. On rubber coated plywood of most trailers and 5-wheels people use aluminum angle brackets anchored with deck screws into the roof, and with sealant under the bracket. On aluminum and fiberglass roof - a typical material on motorhomes - your solution for brackets should be different, so I won't go there.

You could also glue on a few rolls of Unisolar flexible panel like somebody did on their motorhome. There are photos on the List of Installs here at the forum, looks very aerodynamic. This eliminates the need in brackets.

Panels from AM Solar are expensive (as are most their items), there are stores to get it cheaper. Don't know about their installing services. To me, any service is expensive because I can do it myself. For somebody with not much knowledge and no time or desire to plan and install on his own, there is no choice but hire an installer. This trade is not regulated and there were examples of unprofessional and unsafe installs, for all those big $$ paid. So choose wisely.

[pianotuna]

Hi Wo.ody,

Thanks for the compliment--but there are folks here who know lots more than I do.

Have you done an energy audit?

My choice of panel would be high voltage with an MPPT controller. Under 500 watts I'd pick the Rogue 3048

Below 800 watts I'd pick the Tristar MPPT 60 amp unit.

Over 800 watts I'd pick the midnight solar 90 amp unit.

I would probably pick a poly panel rather than mono, because field testing seems to indicate the poly does better in low light. I'd pick the lowest cost per watt.

Wo.ody wrote:
I'm a DIY type so I plan on doing this myself.

Pianotuna...I consider you a solar expert...what "today" panel would you choose?

[free_radical]

Wo.ody wrote:

pianotuna wrote:
Hi,
How did you pick 85 mph?

Just a WAG about highway speeds. Considering the possibility of hurricane or tornado, they should withstand as much as possible. Since most attach panel feet with 3M VHB tape they will "depart" under severe loads.
I'm a DIY type so I plan on doing this myself.
Pianotuna...I consider you a solar expert...what "today" panel would you choose?

I doubt any kind of tape will hold it for very long..
I drilled holes all the way thru my roof trusses which are 3 inches thick and bolted stainless bolts and nuts on,,six bolts per panel..
Sealed the holes with silicone while sliding the bolts in,,,no leaks yet..

[Wo_ody]

pianotuna wrote:
Hi,

How did you pick 85 mph?

Just a WAG about highway speeds. Considering the possibility of hurricane or tornado, they should withstand as much as possible. Since most attach panel feet with 3M VHB tape they will "depart" under severe loads.

I'm a DIY type so I plan on doing this myself.

Pianotuna...I consider you a solar expert...what "today" panel would you choose?

[CA_Traveler]

Which specific solar panel would you choose to roof mount on your motor-home?

Better approach:
1. Figure out your power usage and how much solar would be needed for some typical day in terms of sun/overcast.
2. See what panels and equipment are available and at what cost.
3. See what fits on the roof or ground or elsewhere.
4. DYI or installer installation are considerations.

Most feel constrained to place the panels close to the roof but they can be mounted higher which can eliminate shadows and allow for larger panels.

All of the above involve tradeoffs and there is no specific panel for all. There are many posts on solar including installation etc. You can dig into what works for you or just raise your CC to someone like AM Solar.