Ok so your looking to outfit your off road rig with some portable solar panels? For your backcountry off road overland camping adventure? And wondering what type or style solar panel you will need? Or what you might need to hook it up? My goal is to tackle these topics in this post.
Solar Panel Types
There are three solar panel types monocrystalline, polycrystalline and amorphous here are some of the differences between them
The most popular solar panels used for off road and camping are mono crystalline. And for the most part they have the best power output to size ratio.
- More efficient
- Not as finicky with angle to sun
- Cost a bit more than others types of solar panels
- Cells are black in color
- Better in full sun conditions
- Smaller footprint taking up slightly less room for same wattage panel compared to polycrystalline panel
- Monocrystalline has higher watt output for the same size polycrystalline panel
- Cell are blue panel color
- Little Less efficient than a monocrystalline panel
- Performs just a tad bit better, in a shaded environment. Compared to a mono crystalline panel
- Generally not as forgiving when it comes to angles to sun
- More economical to purchase
- Not typically used for off road camping
Compared to an amorphous panel. Crystalline style cells don’t do as well in partially shaded environments. crystalline style solar panels should be as perpendicular to the sun as possible for best performance. They also can start loosing some output as the temperature goes above 77 degrees fh
- Needs a bigger footprint taking up to, twice or more the area. To achieve the same watt output as a monocrystalline style panel
- They are more Flexible and light weight
- Can handle higher heat better than a crystalline panel
- Can take pretty much the whole spectrum of light from the red to blue. absorbing a wider visible spectrum of light makes it better in low light, cloudy, over cast type weather
- Still good in full sun as well
- More durable than a crystalline panel
- They can still work even if one of the cells gets partially blocked
It’s kinda of a jack of all trades for its weight size to watt output
What Solar Panel Should I Buy?
Picking a solar panel comes down where you live. What your power requirements and application are. And how much room you have for the panels store them, and or mount them.
Rigid vs Flexible Solar Panels vs Solar Blanket?
Semi Flexible Solar Panels
- Thinner profile so they won’t stick up like a hard panel so less wind resistance on a roof
- Flexible panels need to mounted on a good hard flat surface. (gluing them or use eternabond or VHB Tape by 3M)
- Also keep in mind that with flush mounting them to a flat hard surface it will cause them to build up more heat which may reduce the efficiency of the power output of the solar panel.
- They don’t typically last as long either, because of the heat build up. It reduces the life of the panel. Compared to a rigid panel.
- Not typically as durable as rigid (hard) panels, because they don’t have the tempered glass on top of them. Allowing them to possibly get damaged (torn or scratched) easier.
- Flexibility allows to mount them to a surface with a slight curvature up to about 30 degrees to conform to a roof of RV, boat, roof top tent, off road trailer etc.
- Generally not as efficient compared to a rigid solar panel. So you will need more of them. Needing more surface area (bigger footprint) to produce the same amount of energy
- They are lighter and thinner than a hard panel so if portability and weight is a key factor this is the way to go
- Tend to be a bit more costly when you break it down to price per watt compared to a rigid panel
- They might work well mounting them to a clam shell style roof top tent. Though the heat could reduce efficiency. And as mentioned above you won’t have as long as a service life out of it.
Also when mounted flush to a roof your are attracting more excessive heat to penetrate the roof of the vehicle. Causing inside ambient temperature to rise. So might be something to think about. Especially if the real estate of your roof is covered in solar panels. And or your a in very hot environment.
(Extremely) Flexible Solar panel
With a flexible solar panel pretty much has the same attributes as the semi flexible panel other than you can flex them more. So more forgiving when it comes to mounting them. Having more degrees bend and flexibility.
Rigid Solar Panels
- Rigid panels have to be bolted down so could be a little more complicated to install
- They have better heat ventilation because of the air gap underneath of them when mounted helping create air movement. (Having less heat build up in a roof mounted application)
- They will stick up more off of a roof so they won’t be as stream lined as a flexible panel would
- A little more bulky and heavier than a flexible panel
- They have a aluminum frame around them
- Quality panels generally have a tempered glass panel protecting cells making them more durable than a flexible panel preventing the cells from getting damage (scratched or torn)
- Usually more economical when it comes to cost compared to flexible panels
- They generally will have a longer service life, being more reliable than a flexible panel
- Many solar manufacturers offer a way longer warranty on rigid panels over a flexible panel
Portable Folding Solar Panels
A foldable portable solar panel is good to have. Giving you the ability to take it off or out of your vehicle. And move it around to different areas of the camp site. To capture the maximum amount of sunlight during the day.
Portable folding panels are the same as a standard rigid (hard) panel. The only difference is they are mounted in a frame that is hinged. So they fold up to help save space for storage.
Just make sure you get a heavy enough decent gauge extension cable to carry the current. That is if you plan on extending it out from your vehicle.
Keep in mind you want to be able to go out far enough to find the sweet spot for gathering light without moving your vehicle, but you don’t want to go to far and have loss of power from a long cable run. Typically up to about 30ft is a good length.
Some of the portable folding solar panels on the market have a solar controller mounted to the back of them. Although this isn’t the optimal setup for a solar controller, because of heat build up from the sun. possibly reducing efficiency. Its best to have separate units. Though if you do choose to go this route. It would be best to get one with a MPPT solar controller. Which I will discuss further below.
Solar blanket are are good way to role if you don’t have much mounting or storage space for a panel. They also will take up less space being able to fold them up and store them easily. The portability to move them around when your parked or at camp to be able to gather sun light is a great advantage.
Solar blankets don’t usually come with a regulator so you will have to find and install one
112 solar blanket by REDARC (Amorphous)
SunPower 190 solar blanket by REDARC (monocrystalline)
Solar Panel Tips
- Be mindful when you camp in shaded area that your panel may not be receiving enough sun too generate sufficient power.
- Wipe them down before you use them after a dirty dusty drive the dirt will effect the efficiency.
- Solar panels need to be mounted where they can be tilted up or down. To be able to angle to the direction of sun for the most efficient power production.
- Also if your running two different panels next to each other. Keep in mind how you mount them so when you tilt them you don’t want them blocking one another from the sun light.
If you are going to use your solar power system a lot and need to rely on it. Generally best to get a higher quality brand solar panel they tend to use higher quality components. providing more efficient sunlight to power conversion. And usually even if they have shadow cast over part of a cell or the panel it will still work.
Cheaper solar panels (lower quality) could shut down the whole or part of the panel if part of a cell gets shaded or something lays on it.
What Size Solar Panel Should You Get ?
Before you can decide what size solar panel to buy first you will have to figure out what devices, accessories and or appliances you will be taking on your journey. and finding out what the daily usage will be. You will do this by figuring out the total usage of watts each one of your devices use.
Adding Up the Watts
Go to your devices and find what is called the power consumption rating label. It will either be in print directly on the device, or printed on a label stuck to the device or charger.
Look for the output rating. Which will be in watts, volts, amps or milli amps the watt rating is what your are looking for.
On some devices you will only have volts and milliamps listed. So you will have to convert milliamps to amps just divide the devices listed milliamps by 1000 to get the amps.
1000 milliamps equals one amp. (mA) / 1000=(A). 500 milliamps divided by 1000=0.5 amps
If the device gives the watts, then your good, just write it down. If its in volts and amps then you will have to do an equation to convert to watts. For example volts times amps equals watts (V) x (A)=(W).
Once you have the watts. Then multiply the watts by the amount of time you plan on running the item each day. You will have to convert the time to multiply.
Example 15 min= .25, 30min = .50, 1hr=1, 2hrs=2 etc.
Device Watts x Run Time = Watt Hours Per Day (Wh/d).
TV: 20 watts on for 3 hours per day = 60w hours per day
This will give you your daily watt usage. For each device.
So then combine and add them all together, to get the total watt hours per day Wh/d.
Then you can find a solar power calculator online and enter your info. It will suggest the size solar panel requirements you need. And recommended battery size (amp hours).
If you plan on staying out and running off your solar system for a while. It is important to get an adequate solar panel the meets or exceeds your usage requirements so you don’t come up short on power from under charged batteries. Due to an under par and powered solar power system. Also there will be efficiency losses in the system as well through cable and components.
It always best to go with a little larger setup to make sure your batteries reach full state of charge. You don’t want to cut yourself short on power. Plus it will come in useful when the weather is not so fair.
Correct Size Battery
You also need to make sure that that you have the correct size and enough Ah (amp hours) battery or batteries to use with your solar power setup to run all your accessories. The total usage of your devices must be less, than the storage capacity of the battery. More on batteries here.
Hooking Multiple Solar Panels Together
There are three ways to connect solar panels together one is in a series circuit the second way is parallel circuit and third is hooking them up in series and or parallel. They all have some pros and cons. You can check more on that here.
What Is A Solar Controller/Solar Regulator?
A solar controller regulates the voltage from a solar panel to a battery. Sensing when the battery voltage is low, allowing voltage through to charge it. Also when the battery reaches maximum charge. It will disconnect the the power, so it does not over charge it. Over charging the battery will ruin it.
PWM vs MPPT Solar Controller
There are two types of solar controller regulators PWM and MPPT. Both of these units will regulate and prevent over charge of your battery, and preventing reverse flow discharge of the battery. Only allowing voltage to flow one direction (to the battery bank.) However they are very different in how they perform and efficiency.
PWM (pulse width modulation)
PWM (pulse width modulation) is the more basic of the two charge controllers, and although they are usually more budget friendly you typically don’t want to get a PWM. They are not as efficient. And are not capable of optimizing the extra power from the solar panel to the batteries.
A PWM will pull the voltage from the solar panel down to match the battery voltage depending on its state of charge. The nominal voltage from the solar panel or solar array (multiple solar panels) must match the nominal voltage of the battery bank if it doesn’t the PWM will throw away the extra voltage.
To sum it up if you have a 12v battery with a 12v solar panel or solar array) you could use a PWM or MPPT.
Now if you solar panel (or solar array) and battery voltage don’t match. For example you have a 24v output from your solar panel with a 12v battery you will need a MPPT.
MPPT (maximum power point tracking)
MPPT (maximum power point tracking) though usually about twice the price of a PWM. An MPPT solar controller/regulator is what you need. For more performance, energy and amps, being a more advanced and feature rich device than a PWM.
Like the PWM the MPPT has the ability to monitor battery capacity, and charge. Matching the voltage coming from the solar array to match and charge the batteries.
The real added benefit of the MPPT is it will electronically track and deliver the optimal amount of energy from the solar array (panel) to the battery bank. Utilizing all the power from your panel.
Increasing charging efficiency up to about 30%. converting any excess voltage into amperage to charge the battery. Delivering a faster charge to a battery than a PWM would, in the same amount of time. Also an MPPT will help maximize the power output from your solar panel. Even in low light conditions.
MPPT also has the ability for DC load optimization. Which means if you have a appliance (accessory) connected to the battery where the solar controller is connected to. It can not only supply and charge the battery but will compensate and optimize for the load draw of the appliance (or accessory).
How To Size The Right Solar Controller/Regulator
Now the size of your solar controller will depend how large your solar panel (or solar array) is. You need to make sure your solar controller can handle the amount of power being sent to it from the solar panel.
Always best to go with a bigger solar controller than what you need if you have the budget. So you have more room to upgrade If you choose to get a bigger solar panel in the future.
Whatever amperage the solar controller is example 25, 30, or 40 amps you won’t be able to draw anymore power than what the unit is rated for. So you need to take in careful consideration of the load draw of your accessories and appliances that you will be running.
To roughly find how big of a solar controller you need. Is take the total amount of the wattage of your solar panel (or solar array multiple panels combined) and divide that by your systems battery voltage. For example we will use 12v system below as an illustration to get the amp rating for the controller
So lets say you have a 300 watt solar panel and a 12v battery system so you will need a 25 amp charger 300 / 12=25
Just make sure you get a solar charge controller that can handle the voltage of your system.
Solar Controller Tips
- You preferably don’t want a solar controller/regulator mounted on the back of a solar panel. because the heat from being out in sun reduces its efficiency
- For two you want the solar controller/regulator mounted as close to the battery having as short of a wire possible between the regulator and the battery. For proper monitoring of the battery state of charge and increase amp and voltage flow
- If your trying to save a few bucks and going the economy route. Go with a really good solar controller and go more economic on the panel if you just trying to get by. (though it would be best. To set it up top notch from the get go if you have the budget)
DC to DC Charger
A DC to Dc charger is mainly used for charging an auxiliary battery on a vehicle with a dual battery setup. Having a DC to DC charger that is already solar ready with a MPPT (maximum power point tracking) solar controller will give the ability to regulate the power input from a solar panel to the battery.
RED ARC BCDC 1225
RED ARC BCDC 1240
Battery Management System (BMS)
A Battery management system will allow you to charge your vehicle. From a 110Ac house outlet, solar, or from your vehicle alternator .
It will choose solar input first. If equipped, and then Ac power second, when plugged in. Or the alternator charging voltage from your vehicle battery, when it’s running.
Will handle and charge one to multiple batteries in a series. Accommodates AGM, GEL, lead acid, calcium and lithium.
The RED ARC Manager 30, is 30 amp charger putting more current in your batteries to charge them up faster. Also allowing you to keep track of outputs. As well as keeping track of whats running and how much your draw is.
RED ARC Manager 30
Pure Sine Wave Inverter
Having an inverter is important if you have Ac appliances or devices to run. You did all that work setting up a solar power system, but the problems is in a vehicle you will typically have a 12v Dc battery. Now if all your devices are 12 volt Dc than your good shape, but if not, and you need an Ac power supply. Then you will need a power inverter.
There few different kinds of inverters. Square wave inverter (which is rarely seen anymore), modified sine wave inverter. And last but not least the pure sine wave inverter, Which is the preferred choice, and what most electrical devices require today. Providing a clean stable power for computers, radio equipment and other devices that are typically sensitive to Ac voltage irregularity.
Portable Power Station / Solar Generator
Now if your in need of something a little more compact and portable to run your accessories off of. A solar generator might be for you. Giving the ability to move it around with ease and pair it up to a solar panel to recharge. Check more on that here.