So you want to add a solar system to your van build. Great! Solar power is a great way to supply usable electricity to your van anytime anywhere. Plus its a green, reliable, and cheap source of power. The start up cost might be a bit intimmidating. But after installation it's an endless renewable stream of electricity that will inevitably pay for itself. I am here to help guide you on your solar journey. Here is what you can expect from this guide series:
We are going to start off basic to help you get the big picture so you understand how everything works. Then we will break it down and get into the details. It's okay if you aren't tech savvy. I am going to make this as simple as possible.
Note: You are working with electricity which can be potentially dangerous. Be sure to take all necessary precations. If you aren't comfortable installing your system yourself consider hiring a professional or calling on the help of an experienced friend or family member. Although I believe anyone can do anything if they are truly determined this is something you want to get right. Trust me. Safety first.
Table of Contents (so you can skip ahead if you'd like)
1.How Does Solar Work?
Solar power is simple. Light from the sun is converted into electricity which gets stored in some batteries. The batteries then supply power to all of your electronics. Simple right? Okay, maybe not that simple. Let's break it down some more. Solar panels collect light and convert it into electricity. From there it travels to a charger controller. A charger controller's job is to make sure that the batteries are charged safely and properly. Next is the batteries themselves. This where the electricity is stored until it is needed. To use the power from the battery there are two ways. DC and AC. DC or direct current is the natural state of power from the battery and is usually 12V. What is the V for? Don't worry. More on that later. In a van DC might power things like a fridge, vent fan, or lights. AC or alternating current is different. AC is used to power things like a TV, laptop, or coffee maker. To change DC to AC you need an inverter. This device typically converts 12V DC to 120V AC. Now you have 12V DC and 120V AC to run everything you need. Now let's break it down some more.
2.Terms You'll Need To Know
Before we proceed there's some terms that you might need to know. Refer back here if something doesnt make sense.
DC- (Direct Current) the state of electricty in batteries. Note: Your vehicles electrical system is DC.
AC- (Alternating Current) the state of electricty in a house. The electricty in a standard outlet.
V- (Volts or Voltage) Imagine electricty as water running through a pipe. Voltage is like the pressure of the water in the pipe.
I- (Amps or Current) This is like the volume of water flowing through the pipe.
W-(Watt or Wattage) Wattage is like the power created by the volume and pressure combined. Or VxI=W
AH- (Amp Hour) an Amp Hour is how battery capacity is measure. AKA how long it will last.
Inverter- Converts power from DC to AC
Converter- Changes power from AC to DC
Fuse- safety device that breaks open to stop electricty if there is too much current being used
Circuit Breaker- A safety switch that turns off if too much current is used.
3.Figure Out Your System Size
All the parts in your solar power system come in different capacities and sizes and that's all based on how much power you need. So how do you figure that out? This all depends on what devices and electronics your going to use in your van. So first you need to decide what you need to power. Seriously, pull out a notebook, laptop, or phone and make a list. Your whole system is based on this. That being said, be honest with yourself about what you will really need. This includes electronics you want to charge on occasion.
Before you start selecting what you want to use keep this in mind. When it comes to appliances and electronics DC is your friend. Why? Because DC is more stable and efficient. You will also lose some power when converting DC to AC through an inverter so it might be a good idea to try and use whatever DC powered devices you can find. This isn't critical but it will make things simpler when it comes to wiring and it will save you some power.
Here is a simple example setup:
Now that we know what we are going to be using we need to know how much power it all uses. So how do we figure that out? With mathEach items power usage is measured in watts. You can usually find it on a black label or printed somewhere on the device. Or if your looking online you can usually find it in the item description or details box. If it's not measured in watts it might be in amps.
Heres some helpful conversions:
Volts x Amps=Watts
Watts / Volts =Amps
Example: (These are wattage estimates)
|4 LED dome lights||2W each, 8W total|
|Laptop||20W, 60W charging|
These values (W) represent how many watts each device uses per hour. So to figure out how many total watts they will use per day we have to take each times the amount they are used per day and then add those values to find out the total.
|Item||Wattage||Time (hours)||Total Wattage|
|4 LED dome lights||2W each, 8W total||4 hrs||32w|
|Water Pump||36W||0.6hrs or 10min||14W|
|Laptop||20W, 60W charging||2hrs||120W|
|Total=||641W or 1000W Buffer|
In this example I was quite precise in the amount of time used but it doesn't have to be this exact. You could say your going to use all items 8 hrs per day as a general average and that would provide a good buffer between what is required and the total available. If I had calculated it that way I would get very close to 1000W. Now we know how much power we need. Let's round 641w up to 1000w just for some extra power in case we need it.
Not a fan of math? You could stop here and use this online solar calculator from Renogy. All you need to know to use this calculator is your total wattage, how long you want to use your devices, and how many hours of direct sunlight there is available. It might also be a good idea to use it to check your work if your unsure. If you want to learn more read on!
Next is the batteries or battery bank. We need to know how much battery storage we need. These are measured in AH (amp hours).
AH x Battery Voltage= Power in watt hours
100AH x 12V = 1200WH(watt hours)
So this means the battery could supply 1200 watts for 1 hour, 120w for 10 hrs, or 40 watts for 30 hrs. You get the idea. You could also combine two batteries in parallel for more AH or storage capacity. 100AH + 100AH= 200AH x 12= 2400WH
Note: There are three types of batteries and they are each very different. Sealed Lead-Acid, AGM (absorbed glass mat), and Lithium-Ion.
I will go over the basic pros and cons of each.
AGM (absrobed glass mat)
As you might have noticed there are a few ways to approach this. Lead-acid is a cheap option you could find at walmart. It's lower upfront cost will get your system up and running but in a year or two you will likely be returning them with a warranty or buying new ones. AGM is your medium choice. They can be placed anywhere as they won't need to be vented but have about the same specs as lead-acid albeit a tad more efficient. Then theres the long hauler. Lithium-ion. If you have a little extra room in the budget and want something that will last longer and is much more efficient this is what you want. In all categories lithium beats the other types.
Lastly, What size panels do I need? The larger the panel wattage the faster your batteries charge. But here is how to figure out the minimum.
Watts required / direct sun light hours = panel size
641w/6hrs (summer)= 106.83 watt panel our calculated minimum size
1000w/6hrs (summer)= 166.66 watt panel our "just in case" size
Now it's not likely that panels come in these exact sizes so you'll have to find one thats close. like a 100watt or 200watt solar panel. Just like before with the batteries there are different types of solar panels. In this case there are only two that are generally used for this type of application. MonoCrystalline and PolyCrystalline. If you had two 100W panels, one mono and one poly, they would both produce 100W but the moncrystalline one would be smaller in size. This is because monocrystalline is more efficient than polycrystalline so it can achieve the same result with less space. As you may have guessed mono is more expensive then poly do to its efficiency but when your dealing with limited roof space it may be a better option.
Review of Sizing Your System
Lets review. In simple terms the larger the solar panels the faster you charge your batteries. The larger your batteries the more power you can store. And finally your max usage should not be more then the power your panels and battery can keep up with.
Here are some helpful links:
4.What Type of System is Right For You?
Now you know how much power you need but what type of system do you want? Do you want to rely only on solar? Do you want to be able to plug in your van to an external source like a campsite to charge your batteries and run electronics? Do you want to be able to run off of a generator? Do you want your vehicle's alternator to charge your batteries while driving? Or use your house battery to start your van if it's battery dies?
5.The Basics of What You Need
Lets talk about the basics of everything your system will need to operate safely and efficiently. You will find each type of system below. Skip ahead to whichever style fits your needs.
Stand Alone Solar System
This setup is solely solar with no excess connections.
Solar System Connected to Vehicle Battery
This setup allows your vehicles alternator to charge your battery bank while driving or to use your battery bank to jumpstart your vehicle battery if its too low to start.
Solar System With External Connections For a Generators or AC Hookup
This setup will allow you to charge your battery bank with either a generator or AC hookup.
We have reached the end of Part 1 of the Complete Guide to Off-Grid Solar!
I hope you found this guide useful and that you have learned everything you need to know to begin putting together a system. In Part 2 I will go further into detail about the three types of systems I previously mentioned. Together, we will get into the actual installation, wiring, and operation of your system! Part two will be complete with diagrams, schematics, an visual aids. So stay tuned!