How many solar panels do you need? Let's talk about different kinds,
mounting, and where they'll all fit.
Welcome to part 4. We just finished talking about the real heart of an RV solar setup. So now we
need to keep those batteries charged. Again, from the power audit and solar calculator you used back
in part 2, you should have a decent idea as to what your solar panel wattage is going to be.
So first I'm going to talk about small setups. If this doesn't apply to you then you might want to
check out the time stamps in the description and skip ahead to the next chapter. If your
power needs are low and you want to keep it as simple as possible, it doesn't get any easier
than a portable setup. This is often two solar panels, sometimes up to four that you set on a
stand outside your RV or vehicle. That's not to say that you couldn't do more than that, but it
starts to get a little bit unwieldy. Another thing to consider is that oftentimes those with small
setups are also in a smaller RV or a van and don't necessarily have a lot of storage space
to keep all these portable panels when they aren't deployed. You can build your own stand but
honestly, there are so many portable solar kits available now with stands included that I would
just recommend buying one of those. Many of them even come with a solar controller that's paired
with the panels to make it even easier. You pretty much just connect the kit to your battery, set up
your panels, aim them at the sun, and you're all set. As the day progresses you move your
panels a couple of times to follow the sun across the sky. I still would really recommend having a
battery monitor though so you always know how much power you have on hand and when you may or may not
need to conserve a little bit more. Another option here could be a solar generator package. Sometimes
they're referred to as a portable power station and it's really one unit with a battery and
inverter inside of it and a few solar panels used to charge it. Of course, this doesn't integrate
with an RV. It's a standalone unit that you plug your devices into. One drawback to a portable
setup is they can be pretty easily stolen if you leave it out unattended. While I suppose anything
is possible, roof mounting your solar panels mostly solves that problem. It's also nice because
a roof mounted system is always on and it doesn't need to be set up and put away unless you have a
setup where you need to manually tilt your panels. It's pretty safe to say that roof mounting is
the most popular option here. But, before we talk about different solar panels and the ways they're
mounted, we should probably talk about weight. Especially if you're considering a large setup.
Be aware of how much cargo carrying capacity your RV has and how much it weighs right now,
when it's fully loaded. Especially if you full time in it, because if it's also your house,
chances are you're already carrying a lot of stuff with you and you might not have as much
capacity as you'd like. Keeping added weight down definitely played a big role in designing
our system. Flexible solar panels are definitely a lot lighter than rigid panels. Since I used
all flexible panels, I'll talk about those first. Mounting them was really easy. I just used three
large Velcro strips underneath each panel to hold it in place and then put roof repair tape around
all four edges. After a year and a half and even after an unfortunate mishap with a tree, I'm still
really happy with this setup and I would mount them the same exact way if I were to do it again.
I've also had a lot of comments asking about how hot my panels get, if you should have some sort
of air gap underneath them, and if I've had any issues with heat on my rubber roof. My panels
have held up really well. I haven't had any heat problems. And I'd still happily recommend the
175W Renogy flexible panels that I went with. They have a 25 year power output warranty which I think
is important because flexible panels in general haven't always had the greatest track record with
holding up over time. So far, my experience has been that these ones hold up just fine.
Other brands have been coming out with flexible solar panels that have an adhesive backing to
them. They're just peel and stick without any need to tape the edges, which looks pretty nice.
I should add that just because a solar panel is flexible doesn't mean you shouldn't still handle
it pretty carefully. They can flex unevenly when handled and that can actually crack the
individual solar cells in the panel which would make the whole panel less effective overall.
Moving on to rigid solar panels. If I wasn't so worried about weight I would have bought rigid
panels since they're a lot less expensive. They also dissipate heat better and due to the way
they're mounted, they pretty much always at least have a small gap underneath them. So that extra
airflow helps to reduce heat even more which means a little bit more efficiency on hot days.
There are also a ton of different options for mounting them to your roof. One of the simplest
ways is using Z brackets that bolt onto the frame of the panel and then are screwed into your roof.
It should also be mentioned that anytime anything is screwed into your roof it really needs some
sealant to keep the water out. Dicor self-leveling lap sealant might be the most well-known kind
and it's also what I would recommend. Z brackets keep the panel fairly close to your roof so if
there's much of a curvature to it you'll notice that your panels might be slightly tilted along
with the curve. Another option is to mount a series of rails to your roof and then mount
solar panels to the rails. Rails can be raised so your panels can fit over the top of roof vents
and sometimes even your AC units. There's also the option of using mounts that allow
your panels to be tilted. Being able to tilt your panels makes a big difference in the amount of
wattage you can bring down, especially in the winter time. These can be done manually when
you get your RV set up at a campsite and there are even motorized mounts that can be wired in.
If you're only mounting a few panels on your roof and really need to get the most out of them, tilt
mounts really are the way to go. Again, there are a lot of options for mounting solar panels. Had I
gone with rigid panels, I was leaning towards using Z brackets because it didn't seem too
complicated, and as beneficial as tilting panels can be I was looking for a hands-off system.
Seeing as how I didn't go this route though I can't really speak from experience as to which
mounting type is necessarily the best for rigid panels. So let's move on to figuring out what you
can actually fit on your roof and if it's going to meet your power goals. And real quick, if you're
finding this info to be useful could you hit that like button for me? Thanks. For reference,
our fifth wheel is 40 feet 7 inches long. There's a front and rear cap to account for, 2 AC units,
and a number of vents. I was able to install 15 175W panels and there's still plenty of room to
walk around. The first step I would suggest is just to go up on your roof with a tape measure,
take a lot of pictures, and do your best to sketch out a reasonably accurate map of your roof.
Measure how large those blank roof spaces are. You have to figure out how to most efficiently work
around roof vents, AC units, sometimes antennas, and even ladders can sometimes use up some of that
precious roof space. Next, take some more pictures of your roof at different times of day to see how
long the shadows from some of the taller things like AC units are. I did this in the summertime
knowing full well that shadows in the winter would be a lot longer. I spaced my panels around the AC
units as far away as I could, which helps keep the AC unit shadow off of them in the summer.
But go into it knowing that with all the items sticking out of an RV roof, there's no perfect
way to mount everything if your plan is to use all of that space. I also just want to throw
out there that if you're planning on tilting your roof panels, keep in mind the extra shadows that
are going to be cast by the solar panels that are standing up. You don't want to have that
extra power you're gaining by tilting your panels negated by shadows that are then cast across other
panels. If you already have some panels that you'd like to use in mind, find their physical
dimensions and you can start playing with how many you can fit and what the best placement might be.
Ideally you want them all to be exactly the same. Later you'll have to decide what version of series
and parallel wiring you're going to use and keeping them all the same provides maximum
efficiency. Or you might find that the panels you thought you wanted aren't going to work
because they're too bulky or your roof vents are all in the wrong places to fit them. Naturally,
none of us want to spend more money than we have to and it's really common to say something like
"I know I want 1200W of solar panels and these four 300W panels are the least expensive way to
accomplish that." Then only later to find out that a 300W panel is actually 5.5 feet long by
3.25 feet wide and you only have a big enough blank area on your roof for maybe one of those.
Of course, you could probably still use a raised rack to still mount four of those over the top
of whatever's in the way. But, if you want them all to fit without doing that, you'll have to
consider some other panels. It helps to have a few different sizes of solar panels in mind,
get their dimensions, and see how you can plot them out on that map you made of your roof. You
could also make a cardboard cut out the size of the panels you're considering and lay it on your
roof in different places to better visualize the whole thing. After I drew a couple of different
ideas on paper, I took my measuring tape and put blue painters tape all over my roof to represent
where my panels would go. Try to also keep in mind where the actual wiring connections are on your
solar panels so you can also come up with a plan for where you're going to route all the wires for
them. At this point you might have to ask: Does my roof space match my power goals? Having some kind
of raised mounting platform usually provides enough space for just about any array. But,
if you find yourself in my situation where you really need to stick with lighter weight options,
that might not work. Let's say you've maxed out your roof capacity, but you'd still like
to add another panel or two. You can always add a couple of portable panels to the mix. You can
buy one or two or more of the same panels that you're using on your roof, make or buy a stand,
and then wire them into your solar controller in a similar fashion to what you're using for your
roof panels. Now that you've figured out where to mount your solar panels, if you have room to spare
and can afford it, I'd actually recommend upping your overall solar wattage by another 10 to 15%.
I feel like the numbers that you get from most solar calculators don't really account
for less than ideal conditions, and a slightly larger solar array helps make up for that. While
obviously there's not much you can do about a cloudy day that reduces your wattage by half,
you also can't always have control over what angle to the sun you're parked at. And that's where that
extra 10 to 15% comes in. The next thing to consider is wiring. A solar controller is a
battery charger that handles all of that solar wattage and converts it to the proper voltage for
your batteries. Since battery voltage is almost always quite a bit lower than solar panel voltage,
you want your solar controller to be as close to your batteries as possible.
And that means usually running wires through your roof down to wherever the heart of your system is.
A lot of RVs nowadays come with solar pre-wiring. This is a set of wires that's already run through
your roof and down to the battery bay, or somewhere. Sometimes you have to go look for it.
Mine was actually tied up in a loop behind the cargo bay wall. It's helpful if it works out,
but make sure you check how big those wires actually are. The ones that came with ours were
8 gauge which is only good for about 24 amps and it wasn't going to cut it for our setup.
For example, let's say you're using six 200 watt panels that operate at 24 volts each. Two of
them are wired in series which are then wired in parallel to two other sets of two panels. At most
this would be 48 volts, because there are only two in series. Six 200 watt panels make a 1200
watt array and 1200 watts divided by 48 volts would be 25 amps, which would be too much for 8
gauge wire. So pre-installed wiring is really nice if it works out because it'll save you a step, but
make sure that the wiring that it came with can actually handle the amps that you could be pushing
through it. If it's too small or you didn't have solar pre-wiring to begin with, you'll need to run
some sort of new wire through your roof. During our install I ran some large wire through my roof
and installed a junction box over the top of it. This served as a good point for all those solar
panel wires to come together before attaching to the main wires that deliver that power down below
to our solar controllers. As far as the solar panel wiring itself goes, it's most commonly
connected with MC4 connectors. They're waterproof and most panels come with them already attached.
MC4 connectors aren't expensive, and they're pretty easy to make. And fortunately the crimpers
that go with them aren't very expensive either. So, there are lots of other great videos out there
on how to crimp them. If you aren't into that idea you can use waterproof splices to hardwire your
panels, but make sure you have a way to install a fuse between each set of panels that are wired in
series. I went with MC4 connectors and bought fuses with MC4 connectors right on them that just
plug right in. At this point we need to choose a solar controller, and we'll talk about that
actually in the next video, as well as how the whole system ties together and doing some testing.