The many benefits of solar power have attracted not just homeowners but also outdoor junkies as well. This is especially useful for those travelling in an RV. Pair a good battery pack with a set of RV solar panels and you're all set to travel just about anywhere without worrying about losing power.
If you're also looking to try the famous battery and solar panel setup, one of the first things you have to do is to size up both your power pack and panels. A lot of campers go for a standard 100Ah lithium battery, but if you want a little extra output, a 120Ah battery is also a good option.
Now the question would be, what size of solar panels should you pair it with? You'd have to do a bit of math for this, but don't worry, it's very simple to calculate a rough estimate of how much power you need for your panels.
VoltX 12V 100W Folding Solar Mat ETFE
The general rule would be to make use of this formula:
- Amp hours/peak sun hours = amps
- Amps x battery voltage = your solar panel's size
For instance, if you have a 12V 120Ah battery and about 5 hours of peak sun hours in your camping location, the computation would go like this:
- 120Ah / 5 peak sun hours = 24 amps
- 24 amps x 12V = 288W
All in all, you'd need around 300W of solar panels to pair with your 120Ah battery. It's up to you whether you want to break this up into three 100W solar panels, two 150W solar panels, or just one big 300W solar panel as long as everything fits in your RV space.
How Long Will a 120Ah Battery Run a Fridge?
One of the most common questions among campers and off-grid enthusiasts is how long a 120Ah battery can power a fridge. The answer depends on the fridge’s power consumption, battery efficiency, and depth of discharge.
Let’s break it down with a basic calculation:
- Find the fridge’s power consumption – Most 12V portable fridges consume 30–60W per hour on average.
- Convert to amps – Using the formula:
Amps=Watts/Voltx
A 60W fridge on a 12V system draws 5 amps per hour. - Determine the runtime – If you have a 120Ah battery and only discharge 80% (to preserve battery life), you have 96Ah of usable capacity.
96Ah/5A = 19.2 hours
So, a 190Ah lithium battery can run a 60W fridge for around 19 hours before needing a recharge. Lower power consumption, better insulation, and intermittent compressor cycles can extend this runtime significantly.
For longer usage, pairing your battery with solar panels ensures continuous charging throughout the day, making it an ideal solution for off-grid and RV setups.
VoltX 12V 190Ah Pro Lithium LiFePO4 Battery
What Other Factors Should Be Considered When Sizing Your Solar Panels?
It's good to know that there are other factors to consider when sizing solar panels for your 120Ah battery. One would be your battery type. Lithium batteries, especially LiFePO4 batteries, are superior in terms of overall quality. However, you might need bigger solar panels for this, as they sometimes require more output than lead-acid batteries.
Another thing to consider is your solar charge controller, as this will have a big impact on your charging efficiency. This could either be a Maximum Power Point Tracker (MPPT) solar charge controller or a Pulse Width Modulation (PWM) regulator. An MPPT solar charge controller is generally the more efficient choice, but it would still boil down to what kind of setup you have, so make sure you do your research too.
If you want a more accurate computation of what size solar panels you need to charge a 120Ah battery with all these factors included, you can also make use of available solar panel size calculators online. These are convenient to input the details of your battery and panels to get a good idea of the size you should get.
What Is the Best Battery For Solar Charging?
Solar charging requires a solar battery with good storage capabilities. Your best pick for this would definitely be a lithium iron phosphate battery (LiFePO4). These have an impressive capacity and are backed with innovative features as well, such as a built-in battery management system. This BMS makes sure every cell inside the battery is optimized for smooth performance and also provides automatic protection against common battery issues.
Best of all, these power packs are considered lithium deep-cycle batteries, too. This means your battery pack can be safely discharged down to 80% instead of the usual 50% so you can enjoy a longer runtime. It's even more important for off-grid campers who rely on solar energy for power during the evening to power their essential appliances.
Level up your next camping or road trip experience now! You already know how to size up your panels properly, so it's time to go shopping for those portable power sources. Check out our solar panel and battery range at Outbax today for amazing finds at equally excellent prices.
Frequently Asked Questions
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What size solar panel do I need for my 120Ah battery?
For a 12V 120Ah battery, you would need around 300W of solar panels, assuming your location receives about 5 hours of peak sun. You can achieve this with three 100W panels, two 150W panels, or one 300W panel.
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How do I calculate the right solar panel size for my battery?
The formula provided is a two-step process: First, calculate the amps needed with (Amp hours / peak sun hours = amps). Then, calculate the wattage with (Amps x battery voltage = your solar panel's size).
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How many hours can I run my fridge on a 120Ah battery?
A 120Ah lithium battery can power a 60W, 12V fridge for approximately 19.2 hours, assuming you use 80% of the battery's capacity to preserve its lifespan.
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What is the formula for calculating how long my battery can run a fridge?
First, convert the fridge's watt consumption to amps (Amps = Watts / Volts). Then, determine your battery's usable amp-hours (e.g., 120Ah x 80% = 96Ah). Finally, divide the usable amp-hours by the amps drawn by the fridge to get the runtime in hours (96Ah / 5A = 19.2 hours).
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How much power does a 12V portable fridge use?
On average, most 12V portable fridges consume between 30 to 60 watts per hour.
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What does "depth of discharge" mean for a battery?
Depth of discharge refers to how much of the battery's total capacity you use. For example, if you use 80% of a 120Ah battery, you have 96Ah of usable capacity, and the depth of discharge is 80%.
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What else should I think about when choosing solar panel size?
Other factors to consider include your battery type (lithium batteries might need bigger panels than lead-acid ones) and the type of solar charge controller you use (MPPT or PWM), as this impacts charging efficiency.
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Do I need different solar panels for a lithium battery compared to a lead-acid one?
You might need bigger solar panels for lithium batteries because they sometimes require more output than lead-acid batteries.
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Which solar charge controller is better, MPPT or PWM?
An MPPT (Maximum Power Point Tracker) solar charge controller is generally the more efficient option, but the best choice depends on your overall setup.
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What kind of battery is best for a solar setup?
A lithium iron phosphate (LiFePO4) battery is considered the best pick for solar charging due to its impressive capacity and features like a built-in Battery Management System (BMS).
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What is a LiFePO4 battery?
A LiFePO4 battery is a type of lithium deep-cycle battery known as a lithium iron phosphate battery. It is recommended for solar charging because of its high capacity and built-in safety features.
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What does the BMS in a lithium battery do?
A Battery Management System, or BMS, is an innovative feature that makes sure every cell inside the battery is optimized for smooth performance. It also provides automatic protection against common battery issues.
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What is special about a lithium deep-cycle battery?
Lithium deep-cycle batteries can be safely discharged down to 80% of their capacity, whereas other types are typically limited to 50%. This gives you a longer runtime for powering your appliances.
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How do I determine the amps my solar panels need to produce?
To calculate the required amps, you divide your battery's amp-hour rating by the number of peak sun hours in your location. For example, a 120Ah battery with 5 peak sun hours requires 24 amps (120 / 5 = 24).
