Tuesday, August 21, 2012

RV Solar Install - experience and advice (Part One)

Occasionally people will ask us for advice in installing a solar setup in their RV. Roxanne has been suggesting heavily (ouch, quit it!) that some posts on this topic might be helpful.

Hands down, the two best mods we've done to our rig to let us be so self-sufficient have been the solar install and our composting toilet. We highly recommend both for boondocking.

We made the mistake, back when we were still in NY before hitting the road, of hiring our house electrician to rewire our motorhome for us. We had already bought our 4 6-volt batteries to use in our short lived 5th wheel and wanted to incorporate them into The Duck. It turns out the electrician had no clue how RV electrical systems work and he ended up screwing us up big time, which we didn't discover until we were boondocking exclusively and could hardly charge our batteries. So, when our buds Nicole and Darlene helped us install our solar, we first had to undo everything the electrician did before we rewired for solar. It was a big job but we're happy with the end result and now I'm very familiar with how our system works. I told you that story to recommend to you that if you do get help doing your system make sure they know what they're doing. Our guy didn't bother telling us he was winging it, it was bad.

First things first, you need to size your system. How much energy do you use and what sized components do you need to fulfill your requirements (battery bank capacity, how many amps, what size inverter)? There are a bunch of sites online that tell you how to figure what you'll need so I'll just describe what we have and how it's working for us.

Our solar system looks like this:
Panels absent on picture day

We bought our components piecemeal and saved some money that way but you can buy whole systems then just add in the batteries and inverter.
2 135-watt Kyocera solar panels.
Rogue MPPT Charge Controller.
4 6-volt Lifeline batteries wired in series and parallel to give us 12v and 440 amp hours.
Xantrex ProWatt 2000W inverter.

For added convenience, we also have a Xantrex LinkLITE battery monitor, and a remote on/off switch for the inverter.

This might be a good time to talk about inverters vs converters. People often get confused, scratching their head over what does what. The converter only comes into play when you're plugged into shore power or when your generator is running and it's there to charge your batteries. It takes the power being generated by your generator or coming in from the campground power post or from your mother-in-law's house when you're moochdocking in her driveway and converts that ac power to 12v which then gets stored in your battery bank to power your 12v house systems (pump, lights, fans) and to give you stored energy to use when you're not plugged in or running the genny. Think converter think plugged-in.

The inverter is what you use when you are not plugged in or running the generator. It takes the 12v energy stored in your battery bank and changes it (I won't say converts because that could be confusing) to AC to power those things you have that have to plug in, like computers and TV. Think inverter think unplugged. Now, you can install a whole house inverter like we've done so that all of your outlets are live whenever the inverter is on, or you can just get a smaller inverter that will only power, say, an outlet strip in the living room that you use to charge your computer and watch a little TV. Whole house inverters are more expensive and you may decide you don't need that much power available. Ours is a 2000w inverter. We could probably have gone with a 1000W inverter instead and saved a hundred bucks but I like the cushion of the 2000w. I can run our high PSI air compressor to fill our RV tires when I plug it directly into the inverter, I doubt I could do that with a smaller one.

The only time since we've been in the southwest that we've had to conserve energy and turn off the inverter when we weren't actively charging our computers was when we had three weeks of virtually no direct sunshine (Flagstaff, monsoon season). All of the rest of the time we've had more power than we need. Since our solar install in January, we haven't run our generator once. In fact, we've talked about getting rid of our generator because we just don't need it anymore.

Do you have a single space, like a basement bay, for all of the components to live together? Do you have enough space to add a battery to your existing setup, or to go with a different set of batteries (4 6-volt batteries will take more space than 2 12-volt)? Will the compartment you use handle the extra weight of the batteries? Each of our 6-volt Lifeline batteries weigh 66 pounds. How will you run your wiring and where will you mount your panels? Ideally, there's enough room in your existing house battery location for the batteries you need plus the charge controller and inverter. If there's not room then the install gets a little more complicated because you'd have to reroute the existing 12v cabling that is powering your house systems now. Our NY electrician moved some of the house wiring to the very last back basement bay where he mounted the batteries, controller and inverter. Only moving some screwed us up and we had to fix that later but it was good that we had that whole back bay to work with, plenty of space for our needs.

We removed our rear air conditioner to make shade-free room on our roof for our 2 panels. You might think this was insanity but in the two+ years we've been living in The Duck, we never used that A/C and since we boondock exclusively we never use A/C period. We still have the front A/C in case we ever find ourselves plugged in in a hot place - hey, it could happen. Removing the A/C not only freed up space up top but allowed us to have a great path for our wiring since the controller, batteries, etc. live in the basement bay under the bedroom. You really want as short a run of wiring as possible between all your components. Here's some good info to determine what size wiring you'll need - the size is dependent on the distance the wire will run. We used 6-gauge wire for our installation. I think we paid around $100 for our wiring. You should figure another $100 or so for miscellaneous items, like the terminal rings that have to be crimped or soldered onto your wire, dicor sealant for the roof screws, and hardware screws. I know I made a few separate trips to the hardware store when we were doing our install.

I don't want this to get too long and boring (too late!), so I'll continue the subject later. My next post, batteries!

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Teri said...

My two house batteries are inside my RV, in a compartment in the floor behind the drivers seat, I wonder if this would be a problem if I decide to install a solar system when I am done with workamping - probably not for about 5 years.

Paul and Marti Dahl said...

Very nice write up, easy to follow.

We thought about solar and decided to wait a year to see if it would be a good fit for us. So far, we have not boondocked near enough to make it worth our while.

Who knows what next year will bring?

Rick and Kathy Rousseau said...

Like you said piece mealing it together is gradual and less stressful. Each step of the way you can stand back and make sure you are doing everything right.

I have fabricated the battery racks that will saddle the sides of the forward bay in our 5er. Once I run the feeder cables from the roof to the basement controller then the Batteries will go in. Like I said taking my time and doing it right. Be Safe and Enjoy!

It's about time.

stillhowlyn said...

Well done and very informative...Thank you! We installed our 4-110 watt solar panels many yrs. ago and eventually replaced the 2 8-D 12-volt with 6 6-volt golf cart batteries at the suggestion of Solar Electric in Scottsdale, when our very old Heart Interface interverter died, and we replaced with a 2000 watt Magnum. Would be interested in how often you've been told to equalize the batteries. Lynda PS: Pls. do a post on compost toilets in the RV!

Diana said...

I went one step further and took out my converter. When I am plugged in, the solar panels are more than enough to charge the batteries, since that is all they have to do.

Great post!

Bob said...

A little surprised than an "Electrician" would be so clueless. Maybe too proud to do a little research, or just admit that he wasn't familiar with the process?
One of the reasons I prefer to not let trades people anywhere near my "stuff".
Unless I know where they live...

VtChris said...

Great post and oh so timely!! I am curious.....what do you think about removing the converter? And I too, have seriously considered removing the generator now that I have solar.

Annie said...

Teri, I don't know but I imagine you could be set up for a short wiring run from a basement bay to your batteries, or maybe a box in your living room just over the battery compartment.

R&K, sounds good. Will your controller live in the compartment with the battery bank?

Lynda, that's an impressive set up, you must be able to run whatever you want whenever you want and then some. And stay tuned for a composting toilet post!

Bob, we wouldn't have thought bad of him if he'd told us he didn't know RV systems after all. Finding out later was not a fun surprise.

Diana, interesting!

Chris, congrats on your new system! It never occurred to me that the converter could be removed but if you're always going to be in an area where the sunshine is adequate for charging the batteries, I don't see a problem with removing it. We have 2 converters for some stupid reason (the electrician again), I wouldn't mind taking them out and selling them... RV generators are not cheap so I imagine we could recoup a little of the solar install cost by removing and selling it. It's too heavy for me to mess with ours by myself, though, so I'd have to hire it done.

Vicki said...

Oh...don't mind me...just headed to your Amazon store again.

Perth Electrical said...

I'm looking for comments on the solar/electrical system I'm planning to put on a new RV. I'm not a novice to solar and electrical RV mods, but I know there are people far more experienced than I am that post here and I'm soliciting comments and suggestions.

The Good Luck Duck said...

PE, although Annie will write more about this later, you may want to check the right-hand sidebar. Especially HandyBob Solar and Andy Baird's RV website.