Welcome to Part 2, let’s talk about RV Solar System goals and power consumption!
In the last video we went over the basics.
We talked about how RV electrical systems work and some terminology.
So again, I’m breaking this up into chapters in the description.
I encourage you to check that out and skip ahead to whatever is most interesting and
helpful for you.
This topic is just so broad, no two setups are going to be completely alike.
We have 15 solar panels on our roof, but we’ve boondocked in places where there was a couple
in a teardrop trailer who went the full 14 days at this particular BLM location with
just 2 solar panels on a stand and never ran a generator.
So, in this video we’re going to talk about what is required for your RV to function the
way you want it to when you’re not in a campground.
I think most of us get into RVing thinking we’re going to spend all this amazing time
in open areas, out in nature.
Then we end up sometimes packed into an RV park thinking that this isn’t necessarily
what I signed up for.
Our first travel trailer was 23ft long with a single deep cycle battery.
It didn’t have an inverter and the fridge ran on propane, so there really wasn’t very much
power draw.
Of course the very first night we tried to stay at a Walmart, the batteries died and
we actually had to use the jumper cables from our tow vehicle to the trailer battery just
to get the slide back in the next morning!
5 years later, we hit the road full-time in a 41ft 5th wheel with two kids.
This time we had a residential refrigerator that would run on this 1200W inverter off
of the two deep-cycle batteries that our trailer came with.
Unfortunately, the result was still pretty much the same. We ended up having to run our
generator all night long just to keep from killing the batteries.
So let’s face it, RVs are usually just designed to go from one campground to the next.
Some of that is starting to change, but mostly it’s the same old story.
Generators are a great option.
Many RVs come with one or it’s an option you can add when buying new.
Of course that’s not always the case, but portable generators are also a very popular option.
And that’s actually what we went with!
Let’s also just throw it out there that unless you’re looking for a very small solar
setup, a generator is probably going to be the most cost effective means of getting yourself
powered off-grid.
Of course you do have to buy fuel and maintain it, while solar is quiet and doesn’t produce
any exhaust.
One of the many factors that spurred us on to go ahead with our solar project was that
running a generator all night really just isn’t the best boondocking etiquette.
Especially at places like Harvest Hosts, or other similar places like that.
Moving on, let’s talk about how out how much power you need.
This is going to vary wildly for many of you.
I strongly suggest you get a notepad or start in an Excel file or whatever your favorite
method is for getting organized.
Some just try to figure out a really rough estimate off the top of their head and I really
think you’re going to be disappointed with the end result if you do that.
The very first question to answer is what kind of refrigerator do you have and how much
power does it actually use?
Obviously this is an appliance that you can’t just shut off to save power, so it’s a good
place to start.
A refrigerator running on propane uses the least amount of power, but still a little
bit to run the control board.
A 12V refrigerator uses a little bit more, but a full size residential refrigerator is
by far the biggest power hog.
Estimating power usage can be a little bit tricky.
Every electrical device comes with a sticker or information on the power supply about its
electrical needs.
It’s a good place to start, but it’s not always completely accurate.
For example, we do have a big residential style fridge.
The sticker just says it has a full load rating of 7.2A and it’s a 120V appliance.
So together that’s 864W, but that’s really only what it uses right when it starts up.
From doing some testing, I’ve found that very briefly it starts up with a big power
surge, which is why our RV again came with this 1200W inverter to run the fridge when
we’re in transit off of our two batteries.
But right after that great big startup power surge, it actually only runs at about 110W.
It gets even more complicated because of course it doesn’t just run all the time.
You can pay close attention to how often your fridge runs over the course of a couple of
hours and then make an estimate from there.
I’ve found that just to get through a night, I would need a full 100AH Lithium battery
just to run the fridge, nothing else.
Probably the best way to know for sure how much power any of your 120V devices use over
the course of a day is to buy an Electricity Usage Monitor off of Amazon.
Kill-a-Watt has been a really popular brand for years, but there are lots of other cheaper
options out there as well.
You plug it into your wall socket, and then you plug your device into the monitor, and
it will record the power usage over time for you.
I’ll include a couple of links in the description.
I’ll admit, I ended up doing just a lot of math and estimating all of our power usage
when I designed our system.
It does work, but I would suggest you only go that route if you’re super confident
that you can estimate everything correctly.
So, directly testing everything will easily be the most accurate way.
Test or estimate the power usage for everything that you want to run on your system, and document it.
It will take a while, but doing this legwork up front will help you out tremendously.
Take your time with this step because you’ll be basing the design of your entire system
off of it.
Because what you really want to avoid is really underestimating your power needs and buying
a bunch of equipment only to found out that you can’t actually do what you had envisioned.
There’s absolutely nothing wrong with starting small, but make sure you plan for it.
It’s no fun to realize that you don’t have enough solar panels to charge your batteries
back up, but you already maxed out your solar controller so you actually have to buy a different
one.
Maybe you didn’t have big power goals but you would like to be able to run your microwave
briefly only to discover that those AGM batteries you bought have way too much of a voltage
drop under a big load like that and that it makes your 2000 watt inverter that you bought
shut off when it’s time to reheat lunch.
That’s not much fun, but it is an example of another scenario that could happen if you
didn’t plan everything properly.
By the way, we will go over batteries and inverters in the next video.
In the meantime, let’s document what you want to run off of your 12V system.
I strongly suggest buying and installing a battery monitor for this.
Again, you can estimate your power usage, but I found this was especially difficult
for things like lights because being just one of 4 people living in this thing, I wasn’t
totally sure how many hours a day everything was being used.
You will, without a doubt, want a good battery monitor to go with your finished final system
in the end anyway, so you might as well get a jump on it so you can use it to better estimate
your power needs.
I’m kind of partial to Victron equipment because that’s what I used, but that’s
not to say that there aren’t a whole bunch of other really great options out there as
well.
Real quick, if you’ve made it this far through the video would you mind hitting that like
button for me?
It helps others to find the video and I would really appreciate it!
I think most people prefer battery monitors that have Bluetooth built in so they can just
check it with an app from their phone.
It’s super convenient.
Mine actually doesn’t have that because I used a central control panel for everything
instead.
Otherwise I would definitely bought a battery monitor with Bluetooth.
You’ll also find that you might have a handful of devices that are off, but still plugged
in and drawing power.
Having a battery monitor and testing all of your 120V devices will help you to track down
these parasitic draws on your system.
They might not look like much up front, but sometimes over the course of 24 hours they
can really add up!
Especially on smaller systems, the amount of wattage your inverter uses when it’s
not even doing anything can actually be a little surprising too.
Oftentimes with smaller systems, people shut their inverter off at night.
On great big systems, that’s a lot less of an issue.
I also want to mention that another surprisingly power hungry 12V device can be that furnace.
If you aren’t going the super minimalist route, don’t forget to plan in the power
needs of that furnace blower!
The next step is to use one of the many online calculators to get an idea as to how big of
a solar, battery, and inverter system you need to meet your power goals.
If you just Google RV Solar Calculator you will get a ton of results and honestly, most
of them do a pretty good job.
They all ask you to plug in your estimates.
A lot of them say things like Microwave, Coffee Maker, 15W Lights, etc., and you put in how
many hours a day that you use everything to get an estimate.
Those are okay for a rough estimate, and it might even be helpful to use one of those
just to see that your estimate is close to what you actually measured with your own power
audit.
It’s always nice to see numbers match up to know that you’re on the right track.
I really like the calculator from Renogy.
If you’ve already documented your own power usage you can just plug it right in.
If they ask for the efficiency of your charge controller, you can play with what it looks
like with various types.
I think the Renogy calculator has suggestions for Pulse Width Modulation vs MPPT.
I don’t think that you’re going to find that the difference is drastic and we will
definitely go over the specifics of that in again a later video.
This should give you a pretty decent idea as to the kind of solar setup that would meet
your power consumption goals.
I’d actually say that the general estimates for your solar panel wattage is a little bit
low.
I’ve gone over the amount of wattage we see with our setup in various conditions in
our Lessons Learned video as well as our 1 Year Solar Update.
Since our panels don’t tilt and we can’t always aim the back of the trailer towards
the south because campsites face in all sorts of different directions, our actual peak power
is more like 80-85% of our total rated wattage that we have on our roof.
At this point you might start thinking about what would physically fit for you.
Or, if your power needs are really minimal, you might think about a portable setup.
That’s definitely the easiest way to go.
But first, we actually need to talk about something way more important than solar panels.
Your batteries and your inverter or inverters plural truly are the heart of the system and
that is what we’ll go over next in the next video.