How many solar panels do I need for off-grid?

Going off-grid is a great idea until we start to think about water and energy supply. I’ve asked this myself and this is what I’ve found out about going off-grid and have the energy to power at least a fridge, lights, and my phone and computer chargers.

You need at three 300W solar panels to go off-grid comfortably on an RV, a van, or a boat. For a common three-bedroom house, you’ll need at least ten 300W solar panels to supply your home and reduce your dependence on the grid. 

Going off-grid you’ll need more than just solar panels, you will need batteries and power inverters to transform the direct current to alternate current so you can plug your computer charger into the power outlet without transformers. Let’s dive in and see what is really needed to go off-grid besides the solar panels.

How many batteries do I need for a 1000 Watt solar system?

If your energy need is about 1000Wh/day, that means that you need at least one 12V battery with 85Ah of capacity. For reference, most refrigerators consume about 700Wh per day, so this kind of setup will be enough to power your refrigerator and some lights for around 30h in ideal conditions.

If you have live in an RV or in a van, you will want something more powerful to compensate for those cloudy and rainy days. My suggestion is at least 2400Wh and if possible, invest in lithium batteries, they will last you much longer and they are so much more flexible when it’s time to charge as they don’t require you to discharge totally and then charge back again at a steady rate until full. With lithium batteries you can charge whenever it’s possible, just don’t let them die until 0% and don’t let them without using for several months as it degrades their condition quickly.

That huge ceiling is the perfect spot for two solar panels

How many batteries are needed to power a van, an RV, or a boat?

I would suggest at least two 12V 125Ah batteries, that’s 3000Wh of capacity and is enough to power a refrigerator for 4 days, as RV, boat or van-lifer, you know that are some days with rainy, lots of days you will not even see the sunshine, so it’s a great idea to have a powerful system that will power your appliances for days.

It will not break completely the bank, but you will have a system for those weekends you’ll spend with friends or family outdoors. It’s a great way to have clean energy on the go whenever you need it. If you only go off-grid on the weekends or during vacations, save your hard-gained money and don’t go all-in on a system like this. Buy a modest system that has the capacity and the quality that you deserve but that also doesn’t have things that you don’t ever will need.

If you live on a boat, you will have more space (at least in theory), so make it double: four 12V 125Ah batteries and you’ll still have space for your objects, food, and other supplies and you’ll have a 6000Wh power bank enough to power your boat for days without the need to use the fuel generator that produces so much pollution and you need to save the fuel for when it is really needed.

What can a 300 watt solar panel run?

A lot, you can charge your laptop (80W), your smartphone (20W), your 130L 12V refrigerator (50W) and you still have other 150W to spare but is not that simple. This works if have sun all day and if you have enough batteries to power these appliances. In a real-world situation, you would want 600W at least.

That’s 600W produced each hour and if you have at least 5 hours of sun and batteries enough you have 3500Wh per day to spend. That’s enough to power that 150W setup given as an example above for a day in ideal conditions. But as we know life isn’t always in ideal conditions, you may not have energy enough to power your gear for a day. It only takes a rainy day to mess with your off-grid system.

Ideally, depending on where you are, you produce energy for 5 hours a day, with a 300W panel, your solar system would produce 1500W on that day, so you need at least batteries enough to store 1500Wh.  That means that a 12V battery with 125Ah will work just right for this setup.

What is the best off-grid power source?

Solar power without any doubt: it’s cheaper, accessible, there are complete kits that have everything you need from the solar panels to batteries and inverters and if you know one thing or two about electricity, you can do it by yourself.

Install by yourself only if you really know what you are doing as a bad installation can cause a short-circuit and lead to a fire. This is dangerous. If you don’t know what you’re doing, the best thing to do is to contract someone certified that knows his/her stuff.

Why solar is good to off-grid?

It’s cheaper, with $1,200 you can have a solar kit that could do 2,400Wh which includes 2x200W solar panels, 2x 12V 150Ah batteries, and a 3000W inverter. It’s a good kit to start and it will power almost anything you throw at it.

If you want something in the long term, I advise you to put more money upfront and invest in lithium batteries, they will last longer than monoblock batteries as they don’t suffer from memory problems and can hold more charge.

With this kind of batteries, the cost will almost double, but it will be worth every cent spent on that kind of batteries. On more expensive kits, you can control your system in real-time with your smartphone with a Bluetooth connection. We are really living in the future now!!

How many 12V batteries do I need to power a house?

Common American household spends about 30 kWh of energy per day, the most common household batteries hold 2,4kWh so to power your house for 24h you need 13 batteries, if you want for more days, just add 13 batteries for each day of the energy you need off-grid and without recharging.

Usually, people buy batteries enough to power their house for 3 days, it’s a great rule of thumb that is also future-proofing your installation in the case of your family getting bigger or your power necessities changes.

This is a great investment as even if you have a more modest system, it is enough to warm your water and is less money that you will be spending in energy heating your water for showers. The idea is to save the environment and your wallet at the same time and with solar power, you can save the environment at the moment you buy and save money in the long run.


There is no doubt, solar energy is the future and it’s getting cheaper and more accessible each day, it’s a clean energy source and requires little to no maintenance at all. As in everything you own, you need to have proper usage and that will last you for years!

Speaking in years, in few years you will have your investment back in taxes as many governments are still investing heavily in clean energy and you can even sell your remaining energy to the grid for some profit.

If you are off-grid, solar energy is a necessity. You don’t want a noisy fuel generator that needs expensive and frequent maintenance and you are still dependent on fuel prices that continue to go up every year. The setups I’m watching on YouTube, they usually have two 300W solar panels and 2x12V batteries to power the van for some days off-grid and have enough energy to power everything doing that. It’s a choice they made and for what I’m seeing, a good one.


Hi, I'm Sérgio and I'm passionate about saving the environment reducing my carbon footprint and making better choices. Here I will share some tips that I'm learning on my journey of having a way of live that is more sustainable.

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