In the near future I would like to install a solar panel on my trailer to at least maintain my battery. There are amorphous, poly and mono-crystalline panels. We boondock more often during the summer and we don't always park in direct sunlight. One site said I had to buy panels only rated for rv use. I was hoping to buy a panel and controler and have it installed by a local trailer shop. Any opinions as to which type of panel would be best for me.
Go to "windsun.com" and start you research. You will find a wealth of information from a company with over 30 years in the business. They also have a forum with discussions on everything solar.
The site that said the panels have to be rated for rv use is (to be polite) wrong.
Monocrystalline panels are the most expensive and most of the better ones have a 10 year warrany and will last 30-40 years.
Harold and Linda
2009 CT Coachworks siena 35V
W-22 Workhorse 8.1L
I have bever heard of a RV only solar panel. There are some home only type panels, that might not have a frame around the solar panel, and might be molded into roof insulation or something, or some solar panels above 200 watts are just to large to fit easy onto a RV roof, where it really needs to be less than 40" wide.
My suggestion is to measure a couple of places you think a solar panel might fit. Something more than 30" X 50" if possible. Without the shade from the TV antenna (mistake with the original installation of my pair of 45 watt panels). My original set of 45 watt panels, 15 amp controller, and some wire, roof mounts, and instructions for $750 in 1994.
The flexible solar panels require a lot more square feet to make a given wattage, so a 50 watt panel might be twice as large with the flexible panel than a rigid one.
Also compare with dollars per rated watt, then don't expect the wattage to be nearly as much as advertized. Expect they will actually charge about 80% of the advertized rate. Or take the rated amps X 5 to get about how many amp hours you will collect in a day.
And while you might carefully count how many amp hours each light might use, remember to add about 35 AH for the propane, CO detectors and refrigerator draw.
I just figure that you should be collecting about 50 amp hours per day, then what is in the battery will last about 4 days - and will eventually discharge to almost nothing. But if you collect more like 75 AH, then you can refill the battery each day.
A while ago at wholesalesolar.com - another good source for panels - I saw a few panels with warning "not for marine use". Probably some materials in frame or soldering. But this is not usual. Most panels are perfectly OK for RV, there is no "RV specific" panel. Also, the type - polycrystalline, mono, amorphous - doesn't matter.
If you only need it for battery maintenance - not as a source of power for dry camping - get some small panel with as cheap controller as possible, stay away from panels rated to 24V nominal (27-36V Vmp) as those require expensive controller, and stay way from flexible laminates - those cost more than rigid panels.
Make sure you really need to "maintain" only, i.e. to compensate for self-discharge of batteries for when trailer is not in use. Sometimes people say "maintain" and really mean keeping batteries full when boondocking, i.e. getting enough power for their daily needs. Maintaining is a few amp/hrs day, daily use is dozens or hundreds of amp/hrs.
Edit - PS: to cut down the current draw for when not in use, you need to disconnect ALL loads, including fridge, propane/CO detectors, and radio. Otherwise you'll need dozens of amp/hrs a day when in storage, rather than few amp/hrs a day.
* This post was
edited 05/24/12 03:11pm by Almot *
Shipping cost can really raise the price. If you have a local seller to pick up it will really help.
I assume you are looking for a nominal 12v panel, 80w to 160w, PWM controller.
I bought mine at http://www.solarblvd.com/ but they seem sold out of the panels you are probably looking for.
The major equipment should be $2 to $3 per watt or keep looking. It is way easy to spend $10 per watt. Although there is a new tariff on Chinese panels that could be pushing the price up. If you find some close outs at a good price jump on them quick.