Tuesday, November 18, 2008

RV Solar Made Simple

I said no pictures but here is one with parts of 3 solar panels showing. One across the front, one on the driver's side, and the corner of one across the back. The big one can not be seen as it is in the middle of the roof. I did not like them showing as we had a new paint job, but I wanted the use of them so, I got over it.
This is not rocket science. Well, maybe it is, but we don't have to understand it to get the benefit from someone else's work in developing it. If you like camping away from the beaten path, for free, this is great. One time investment. Even when in an rv park that charges for your electricity, don't plug in unless you need air conditioning. Everything in an rv runs off 12 volts or from your inverter.
I told you that I failed algebra. I can work out problems but the teachers did not like how I did it. Well, I understand that but many of those teachers are still working and I am retired. So, I don't care if I did fail a class or two, ha. Simple is the easiest way to get to where I want to go.
Out west the cattle ranchers catch rainwater in a big barrel , up on a hill. Sometimes they may pump it into that container.
I see the (1) solar panel as that container. It catches the water. The bigger the container the more water I can get.
Then they use a water pipe to get that water from the big container sitting on the hilltop to to the trough. That pipe is the (2) cable from panels to the drinking trough. The larger the water pipe the more water that can flow.
At the trough they have a float shut off control. That is our (3) charge controller. It will open and close as the trough needs water to keep it full.
The watering trough. The bigger the more water it can hold for the cattle. (4) batteries.
That is it, 4 main components in an rv solar system. Read on, I can save you lots of time and money.
If the rancher has trees on the hilltop he won't put the water catcher under them. We can not shade our solar panels either. They will not catch the energy from the sun. Placement on the rv is very important. Don't let the airconditioner or pod shade any part of your system. That is why I have one panel in front and rear, that show from the ground. I could have hidden both of them but the air conditioner would have shaded them, or partially covered the path from the sun to the rv roof. Not a good thing. Sure, at certain parts of the day some of the panels wont get direct sunlight but that is only early in the morning and late in the evening on our coach, when I park it west and east. When north and south, it is less shade and more sun. Think about this before installing them. Measure your space before you buy the panels. I bought mine one at a time. After I took up prime real estate with the first one I measured each spot on the roof before buying another one. Then, I looked for panels that would fit into those remaining, unshaded, spots. One beauty of solar on rv's, you can add as you go, if you plan ahead.
One note here, if using 12 volt system, buy only 36 cell panels. They will all say how many cells. Old ones had 32. Don't buy them or mix them in with 36.
The rancher wants water pipes that will flow good so the water does not evaporate in the hot western sun before it gets to the trough. We want large cables that will do the same. I use number 6 welding cable. Now, you can use #10 cable or even smaller depending on your panel sizes, to the junction. But, from there on into the controller, use big cable. If you don't you will not get a good flow of water to the trough and your batteries will never get full. The cows will die for a lack of water. The junction is where you tie all of your panels together. Ask me how I know about cable size. Teri and I had to pull #10 out of the GMC and replace it with the #6 welding cable. Not fun. I picked up a 100 ft. roll of welding cable on ebay for 30 bux plus 15 shipping so look around. Heat is an enemy to our water pipes, cable. Cows do not like hot water. Do not run it close to any heat like the refrigerator back. If you must use the refer vent, tie the cables so they are as far away from any generated heat as possible. There will always be heat in that vent, even when running fans as I do. Just a word of caution. Don't ask where my cables are run into the rv.
The float shutoff, charge controller. You get what you pay for here. Once again, ask me how I know. Ripped out a cheap one to replace with a good one. Wasted money. You must buy a good controller. My buddy Rob told me this when I was building my sytem. I did not hear him loud enough so listen, GET A GOOD CONTROLLER the first time. You want one that will handle any upgrades that you might have in the future. A 40 amp controller will more than do you. I got a good deal on a Xantrex 60 amp so I bought it. Whatever brand you get it must be a 3 stage with adjustable set points. Look around and you can pick one up on sale for 150 bux. Don't settle for anything less than a 3 stage with adjustable set points. Set points let you contol where the "float shut off" in the water trough sets and how much water gets into the trough. We can talk all day long about charge controllers but that is not keeping things simple as I promised.
Batteries, the watering trough. Batteries are expensive. Go to Sam's Club and check to see what the price is on their 6 volt deep cycles. Last time I looked they were under 70 dollars each. The best bargain out there for rv house batteries. Not the best, but by far the best bargain. They will work fine. This is a watering trough. Take care of it and it won't spring a leak for 5 or 6 years. The more expensive batteries might last longer but I doubt it. No debate, this is my blog. Rv's come already wired for house batteries. Most have one 12 volt deep cycle. It is not enough for real boondockers. When it is time, replace that single 12 volt with 4 - 6 volt batteries. Wire 2 in series for 12 volts then parallel them with the other two and still have 12 volts with twice the amperage. Amperage is how much water the trough holds. The more the better. More batteries can be added. We find 4 6 volts do us just fine. Never run the batteries below 50% charge. Will kill them quick. You can get meters, I have them in our system.
There it is, very basic. We use 4 panels on our roof giving us a total of 300 watts of power. That combined with with the batteries gives us all the "water" that we need to keep our "trough" full enough. Now, if it is real cloudy for several days in a row you may need to fire the generator but RVer's like sunny weather. We move toward the sun and the solar works fine for us.
We do not tilt the panels and you won't either unless you are a fulltimer. Don't waste money on tilting brackets. Make your own mounts. Just L brackets. Use butyl tape to keep from leaking. Oh, I hated drilling holes in my new paint on the roof top. Seal them good. Get an extra solar panel to make up for not tilting. If you start with one or two panels, you can add later if you plan ahead. Big cable and proper controller. I started with one 115 watt panel. Did not plan ahead. Had to redo everything. Look at new priced panels on the internet to get an idea of what they sell for. Watch on ebay. I got 3 on there. 1 new and 2 used. They have dates on them and are good for 20 plus years so check dates on used and buy only 36 cell 12 volt panels. We have 1500 dollars in our entire setup. That includes money I wasted. Our system more than paid for itself in a year. That is savings in campground fees at 25 dollars a night.
I take no credit for anything here except for sumarizing this information. I have not even scratched the surface of this topic. My only intention is to get you to thinking. This is a simple process, installing solar, and anyone can do it.
Thanks for stopping. I must get on with my retirement now.


At November 18, 2008 at 1:22 PM , Blogger Ben Campbell said...

Great Blog Dan, Very helpful. I'll put a link to it from my site. I love the cattle trough comparison!

At November 18, 2008 at 4:27 PM , Blogger Dan & Teri Gregg said...

Ok Ben. Thanks for comment. Hope the simple illustration helped folks realize that anyone can have solar in their rv if they want it.

At December 15, 2010 at 3:00 AM , Blogger Thesolar said...

Solar panels being used for many years now, but cost of production to have own solar powered generator at your own home typically very high but the efficiency low, making them largely ineffective source of energy.

Solar Panel Plans


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