12 volt solar panels are a marvel when it comes to affordable, portable energy, free from the sun. But what can a 12v solar panel power? And what shouldn’t you use them for? Although 12 volt solar panels are affordable, they also face limitations that make them uneconomic in some situations. You should understand these limits before deciding to go down the 12v path. To help you decide, we answer the internet’s top 20 questions about the capabilities and limitations of 12v solar panels. Once you read this post you’ll know whether 12v solar panels are for you, what size to buy, and where to use them.
1. What is a 12 volt solar panel?
Have you even seen a fold out blanket with solar panels sewn into it? Chances are those were 12 volt solar panels.
A 12 volt solar panel is just a photovoltaic panel that runs at a lower voltage of 12 volts. It comes in different sizes and applications.
Each panel is made up of solar cells, which convert sunlight into electricity. The electricity is passed through the panel and out into other appliances by busbars – little wires that run through each cell. The more cells in the panel, the more electricity it can produce.
12 volt solar panels are traditionally used to power 12 volt electrical systems.
2. What types of 12v solar panels are there?
When looking at 12 volt solar panels you will come across 3 different types:
- Amorphorous
- Polycrystalline
- Monocrystalline
Amorphorous solar panels are the least expensive and have the lowest efficiency. They are made up of a-Si, or amorphous silicon. This type of silicon is not pure and has a lower conversion rate than other types of solar cells. Amorphorous panels are usually thin film, and typically seen in applications such as solar blankets and solar awnings or shades.
Polycrystalline solar panels are slightly more expensive but have a higher efficiency than amorphorous panels. They are made up of poly-Si, or polycrystalline silicon. This type of silicon is made up of many small crystals that have been fused together.
Poly panels are a good choice if you have a budget to stick to.
Monocrystalline solar panels are the most expensive but have the highest efficiency. They are made up of mono-Si, or monocrystalline silicon. This type of silicon is made from a single, large crystal.
If you can afford it, monocrystalline panels will give you the biggest bang for buck over the smallest amount of space.
3. Should you use fixed or portable 12 volt solar panels?
12 volt solar panels come in fixed and portable models.
Fixed solar panels are usually screwed directly onto a building or vehicle. You can fix 12 volt solar panels to a boat, a caravan, a 4 wheel drive, a motorhome or even a tiny house. Just about any recreational vehicle works!
Fixed solar panels are usually mounted flat to a roof. This means they are not optimised to capture the arc of the sun throughout the day as it moves from east to west. But you can carry more solar panels when they are fixed to a vehicle.
Portable solar panels come on a mounting frame with legs. You can move them around to follow the sun. Their portability is an advantage when trying to get the most out of your panels.
However, all 12 volt solar panels do experience energy loss if you place them too far from whatever they are charging. It’s best to remember this when moving them around!
4. How much power does a 12v solar panel produce?
The amount of power that a 12v solar panel produces depends on the size of the panel, the type of solar cells used, and the amount of sunlight that the panel is exposed to.
12v panel sizes range from small (10 watts or 12 watts), to large (200 watts). 100 watt panels are the most common in 12 volt systems for back up power, or power ‘on the road‘.
A small 12v amorphous solar panel can produce about 10 watts of power at peak sunlight, while a large 12v monocrystalline solar panel can produce about 200 watts of power at peak sunlight.
The average output of the solar panels is not the same as the rating on the panel. This is because power output is affected by the angle of the sun and the panel, shading, cloud cover and even ambient temperature.
We use 70% efficiency factor to work out average solar output (100 watt panel produces 70 watts on average).
12 volt solar panels can also experience energy losses when trying to send the power over larger distances using long cables.
5. What can i use a 12 volt solar panel for?
12 volt solar panels are often used where 12 volt direct current (DC) appliances are used. Like many other adventurers, you can use 12 volt solar panels to power your 12v DC appliances in RVs, motorhomes, caravans, camping, and boats.
The panels are light and portable, so you can also use them to charge things like mobile phones and laptops on the go. You might find these types of solar panels built into bags and fold out kits.
It’s worth remembering that 12v DC appliances are not as common as the 240v/120v AC appliances we use in homes. For that, they’re a lot more expensive to buy than regular 240v AC home appliances.
The 12 volt solar panels themselves are typically less expensive than higher voltage panels, and they are easier to install and maintain. As a result, they are a popular choice to add solar power for emergency backup of critical equipment or to power single loads (such as outdoor water pumps).
Because 12v solar panels work at lower voltage, they’re generally safer and don’t require an electrician to work with (up to 120v DC). So you can do much of the system set up yourself for a 12v system.
You can also use 12 volt solar panels to back up one or two AC appliances in your home, with an inverter. The inverter converts the voltage from 12v to 240v. Because 12v solar panels and batteries are generally smaller in power output, you can’t run 240v appliances for long with 12v solar panels.
We covered different solar panel uses in more detail in our article. 6 solar panel uses to secure your power supply Check it out!
6. What can a 12v solar panel power?
12v solar panels can power a diverse range of electrical equipment. Let’s take a look at what they can power:
12 volt appliances, with a battery and solar controller connected.
12 volt appliances are not the same as the appliances you use in your home in Australia.
For a start they run on DC (or direct current power) just like 12v solar panels do. They’re also smaller in size than their AC equivalent appliances and don’t consume as much power.
Because they are more efficient and don’t require as much power, you can more easily run small DC appliances from batteries and solar panels. So you’ll find 12 volt solar panels being used to power these appliances wherever people need power ‘on the go’. That’s typically in RVs; caravans, motorhomes, boats, 4 wheel drives and some tiny homes.
A 12v solar panel can be used to power many small 12v appliances, including:
- lighting,
- entertainment – radios & TVs
- very small water pumps like camping pumps,
- mobile devices – phones, laptops,
- 12v refrigerators.
- 12v motors
- Fans
A 12 volt battery, with a solar controller (or regulator) connected.
You can also charge a 12 volt battery with your 12 volt solar panels. You might do this if you need back up power, or power on the road. The most common type of battery to use with 12 volt solar panels is a deep cycle battery. These are designed for continuous charging and discharging.
There are different battery chemistries for deep cycle batteries. Two common ones are AGM and lithium ion phosphate.
You need to know the wattage of the 12v battery to know what size 12 volt solar panels are suitable to charge it.
You don’t need to have any appliances (load) connected to the battery to charge it with your solar panels. You might just want recharge a 12v battery to use later. In an emergency or a power outage for example.
Small 120 volt or 240 volt home appliances (with an inverter).
It’s useful to know that you can also charge home appliances with a 12v solar panel. But there is an extra device involved. The device is called an inverter. In this case, it’s a DC to AC inverter.
120 and 240 volt home appliances run on AC (alternate current) power. To run them with a 12v solar panel, you will need to convert the DC power from the solar panel into AC power.
The same device will also convert the voltage from 12v to 240v or 120v. 220 to 240v is the common voltage used in Australian household appliances.
You can use this simple rule of thumb if you are having trouble working out how to size your solar panels, batteries and inverter
= 1 Watt of solar panel to 1 AH of battery, to 1 watt of Inverter.
It’s hard to go wrong with this rule of thumb!
7. What can’t you power with a 12 volt solar panel?
When we say ‘can’t power’ that’s not entirely true. You can power the electronics below but you will require multiple large 12 volt solar panels and a large battery capacity. But it’s not practical or economical to use 12 volt solar panels in larger arrays. They simply don’t produce as much power per panel as higher voltage panels.
For the cost of the panels and battery you would need, there are more effective options. We run through what they are down below.
It’s impractical and uneconomical to power these things with a 12v solar panel:
Airconditioners
Aircon units draw way too much power to run for any length of time, using 12 volt solar panels. They also use a lot more power to start up than to run. And often need more start up power than 12v panels can provide.
Heating
Space heating or water heating also draws a lot of power. In the thousands of watts sometimes. The draw you need to power these appliances is simply too large and becomes too expensive to meet with 12 volt solar panels and a battery.
Cooking
Your toaster and your kettle use a surprising amount of power. You have to think to yourself, is my toast worth the extra money I need to spend on solar panels and a battery to run it? The same with an electric fry pan or counter top oven.
When its better to use gas and wood
For emergency or backup heating, cooling and cooking you’re better off using gas and wood than trying to power these with 12v solar.
A gas BBQ is a great backup cooking option in power outages. We also have a single ring counter top gas burner to pan-fry meals and boil the kettle. It hooks up directly to a 9kg gas bottle.
You can even buy a portable continuous gas hot water system these days.
In our southern states, a wood heater can be a marvellous thing in a power outage. We recently had a 4 day power outage in zero degree overnight temperatures here in Tasmania. When we bought our house in 2021, we purposely installed a wood heater that you can cook on for exactly this scenario.
We had heating and the ability to cook food inside when it was 3 degrees in neighbours lounge rooms.
Wood heater come in compact sizes for motorhomes, caravans and tiny homes too.
Using gas and wood to supplement your energy needs in an emergency or when you’re on the road, is more cost effective than trying to meet those needs with large solar battery systems.
8. What size 12 volt solar panel do i need?
It seems confusing, but the answer is actually pretty simple. You size your solar panels (in watts) to suit the battery and appliances you want to power.
You also make sure the voltages of the batteries and appliances match, if you’re using 12 volt solar panels. Here is an example of how you might size your solar panels based on the appliances you’re going to use:
In this example, you’ll need 2 x 200 watt 12 volt solar panels to power your daily energy use of 900 watt hours. You’ll pair this with a 100Ah (1200 watt) lithium battery and 40 Amp 12 volt solar controller.
If you want to know how to do these calculations for yourself, check out our post ‘What size solar panel do I need to charge a 100Ah battery?’
If you’re using 24 volt panels, you can efficiently use an inverter to step down the voltage for 12 volt appliances. Its less efficient (and economical) to step up the voltage from 12 to 24 volts if you have 24v appliances.
9. What are the limitations of a 12v solar panel?
The biggest limitation of a 12 volt solar panel is that they can only produce enough power for small devices. If you try to use a 12v solar panel to power something that requires a lot of power, like a fridge or a TV, it will not work.
Also, you can only power 12v appliances efficiently. You can use an inverter to step up 12v power, but you’ll loose a lot of the energy. So it’s a temporary work around more than a permanent solution.
Another limitation of 12v solar panels is that they can only be used in areas that get a lot of sunlight. If you live in an area with long winters and short summers, or if you live in an area that is mostly cloudy, a 12v solar panel will not be very effective.
Finally, 12 volt solar panels can experience energy losses over long cables, because of their low voltage. So the panels need to be placed close to whatever they are powering. This limits your ability to move panels around to capture peak sunlight, in some instances.
10. What are the benefits of a 12v solar panel?
The biggest benefit of a 12v solar panel is that it is cheaper than other types of solar panels. This makes them a good option for people who want to use solar power but don’t have a lot of money to invest.
Another benefit of 12v solar panels is that they are easy to set up and use. You don’t need any special equipment or skills to install a 12v solar panel, and you can start using it as soon as it’s set up.
You don’t need an electrician either. Generally in Australia, 120v DC (direct current) is the cut off for doing unlicensed electrical work.
Finally, 12 volt solar panels are versatile and portable. They’re light-weight and smaller than 24 volt panels. You can move them around to chase the sun, and carry and store them easily. They’re even built into some items such as blankets and bags.
These features make 12v solar panels affordable and practical for a small amount of emergency backup power with a battery, or for power ‘on the go’.
11. What is the highest wattage 12 volt solar panel
Stringing 100 watt 12 volt solar panels together is common, to get a larger wattage 12 volt array. ‘Solar kits’ are often sold with 3 or 4 x 100 watt panels in the kit, to make up a larger system.
The largest 12v solar panel that you can buy in Australia is the Renogy 175 watt panel.
12. Can I plug my appliances directly into the solar panels?
It’s not common to plug 12 volt appliances directly into 12 volt solar panels. Most of the time you will use a battery with the panels. You also need a solar controller to regulate the power from the solar panels to the battery. If you were to try and connect your applianced directly to the solar panels, its best to run the power through a DC to DC converter.
13. What size solar panel will keep 12 volt battery charged
It depends on the size of the battery. A popular 12 volt battery size is 100 Amp Hours. That’s the equivalent of 1200 watts. So you need typically need enough solar to charge 1200 watts in one day (5 hours of sunlight on average).
The solar panels need to give you 240 watts per hour for 5 hours (1200 watts / 5 hours = 240 watts).
You might think a 300 watt panel will do this, but it won’t.
That’s because its best to allow for shading, clouds and the angle of the sun when working out the solar output of the 12v panel.
So a 100 watt solar panel will not produce 100 watts on average. 100 watts is the nominal rating, under test conditions and perfect sunlight. We allow 70% efficiency (a 100 watt panel will produce 70 watts on average).
300 watts of solar panels will produce 210 watts on average.
To be safe, you’d be best off using 400 watts of panels to keep a 100Ah battery charged (400 x 70% = 280 watts).
You probably won’t be fully discharging your battery’s full 1200 watts each day either. This will kill the battery life over time.
If the manufacturer depth of discharge is 80% (lithium ion) you’ll need 960 watts from your 12v solar panels in one day, for example. If it’s 50%, you’ll only need 600 watts to recharge it in a day.
So there is some flexibility built in to these calculations.
If you want to keep the battery charged PLUS power your appliances at the same time, add the full battery capacity (1200w) to your total daily load. So if you use 900 watts per day, you’ll need enough panels to produce 1700 watts in one day.
14. What is difference between 12 volt and 24 volt solar panel?
12V solar panel is generally available in 10W, 20W, 40W, 50W, 100W, 125W, 160W and 180W, whereas 24V is available in 330W and 350W.
A 24 volt solar panel has twice as many cells as a 12 volt panel but otherwise is identical in appearance.
A 24v panel can generate 24 or 12 volt electrical power (with an MPPT solar controller installed). It also produces more electricity than a 12 volt solar system.
You’ll find 24 volt systems in motorhomes, homes, farm, or other situation that requires more electricity.
24 volt systems don’t suffer the same energy loss when sending power over longer distances as 12 volt systems. So they’re more flexible to install.
24 volt panels are more expensive to buy, but generally cheaper to install due to the cost of 12 volt wiring and parts.
15. How many watts does a 12 volt solar panel put out?
12 volt solar panels come in different watt sizes. A popular panel size is 100 watts. But this is the panel’s ‘nominal capacity’; the amount of energy it can produce in test conditions under perfect sunlight.
The amount of actual output depends on the type of panel (amorphorous, polycrystalline or monocrystalline), as well as the external conditions. Sun angle, shading, cloud cover and ambient temperature can all impact the output of your solar panels.
To capture all of these things we allow an efficiency factor of 85% in good sunlight, or 70% on average. So a 100 watt solar panel should produce 85 watts in good sunlight, and 70 watts on average.
16. How many amps does a 200w 12v solar panel produce?
The conversion of watts to amps is straightforward. The formula is:
Amps = watts / volts
When it comes to solar panel output in watts, you also need to account for the efficiency of the solar panels due to shading, clouds and sun angle. We use 70% on average.
So a 200 watt solar panel produces 140 watts of output on average.
Using our formula above, the calculation is:
Amps = (200 watts x 70%) / 12 volts = 11.6 Amps.
17. How many amps does 300 watts of 12v solar panels produce?
The first thing to understand here is that 300 watt 12v solar panels don’t exist. Most 12v solar panels max out at 200 watts. So you may have 3 x 100 watt 12 volt solar panels in this example.
Following the calculations above:
Amps = (300 watts x 70%) / 12 volts = 17.5 Amps
18. How many amps does a 12 volt solar panel produce?
To work out how many amps a 12 volt solar panel produces, you need to know the size (in watts) of the solar panel.
The formula to work out amps is:
Amps = watts / volts.
We also use 70% efficiency on average for the solar panel output (a 100 watt panel will produce 70 watts on average).
For example for a typical 100 watt 12v solar panel:
Amps = (100 watts x 70%) /12 volts = 5.8 Amps
19. How long will a 50 watt solar panel take to charge a 12V battery?
It really depends on the size of the battery; how many amps / watts of power it provides.
How many watts or amp hours it provides will determine how long it take to recharge that power back into the battery cells.
Using our example above, a 50 watt solar panel is too small to charge a 100Ah battery. It would trickle charge the battery at best, over 2 to 3 days. It’s unlikely to have sufficient power output to charge this size battery to full capacity.
20. How fast will 300 watts of solar panels charge a 12 volt battery?
300 watts of solar panels (12 volt panels) will charge a 12 volt 100 Amp Hour battery in around 5 hours.
For a more detailed answer, check out our post What size solar panel do I need to charge a 100Ah battery?
