How many batteries do I need for a 100-watt solar panel on a van?

Van-living has now garnered some cult-like following, with more people mixing this growing trend with the need to have the same home comforts in their motor-van. But since you’re always on the move, you need to find a solution to generate your electricity if you want to recharge your phone or laptop—the answer: a solar system.

Solar panels can be attached to the van, but it can be challenging to choose the size of your solar panels. If you’re in the complete unknown at the moment, I highly recommend you to check the Renogy 100-watt Starter Kit as a first step. It will allow you to have a better idea of your electricity needs.

If you went for a setup with a 100 watts solar panel, you might still have some questions about the size of your battery bank. Solar Industry studies estimate that a 100-watt solar panel can produce up to 30 Ah of battery charge with a 5-9 hour timeline sun exposition.

The above estimate depends on your location and orientation of your solar panel installation. Still, if you expect about 3–9 hours of sunlight in a day per day, this means your solar array will produce anywhere from 100 W * 3h = 300Wh on a cloudy day to about 100W * 9h = 900 Wh on a sunny summer day. Therefore, I would recommend having a minimum of one 60Ah lithium battery option. Of course, you can get a more prominent battery bank, allowing you to store more energy, but I won’t go under 60ah WITH Lithium.

If you decide to buy a lead-acid battery, you should know that you’ll be able to use only 50% of their rated capacity. Lets’ assume that your solar panel produces an average daily solar production of 500 Wh; you will need at least a battery bank that can store about 1000 Wh.

Lithium-ion batteries are very different from lead-acid and AGM: they can be discharged almost entirely.

Lithium batteries are more expensive, but their lifetime is much longer, they’re lighter and need less maintenance. Important points to note when choosing your battery for your solar energy system.

Lets’ take an in-depth look at some of the criteria you can use when choosing a battery for your solar setup.

– Battery Capacity & Rated power

Battery capacity is the total amount of electricity that a solar battery can store. It is measured in kilowatt-hours (kWh) units.

Battery power rating is defined as the amount of electricity that a battery can deliver. It is measured in kilowatts (kW).

– Depth of discharge

It refers to the amount of a battery’s capacity that can be used without damaging the battery itself. If you have a 10 kWh battery rated at DoD of 90 percent, you shouldn’t use more than 9 kWh of the battery before recharging it. A higher battery DoD means you can use more of the battery’s capacity in layman’s terms.

– Battery life & warranty

Battery life is generally defined as the number of complete charge-discharge cycles the battery can hold before losing its capacity. It is affected by many different factors like discharge current, depth of discharge, operating temperature. If you want to know more about it, I recommend checking this article by Battery UniversityOpens in a new tab..

Which type of battery is the best for a 100-watt solar panel?

I recommend lithium-ion batteries for an off-grid solar panel system. even though they are more expensive, they are a good investment that will save you in many situations. They have significant advantages compared to other types of batteries. Let’s have a look.

– Lead-acid

Lead-acid batteries are widely used in off-grip setups because of their relatively low cost and minimal care.This type of battery has a relatively short life cycle; they have a lower DoD and weigh more than Lithium batteries.

They are recommended for RV owners who want to go off the grid and save money on their battery storage bank. You should also know that lead-acid batteries need regular maintenance.

– Lithium-ion

Lithium-ion batteries are lighter, slimline, and very compact when compared to lead-acid batteries. They are also highly rated in terms of DoD and have a longer life expectancy.

Lithium-ion batteries are an investment in terms of pricing when comparing them with other battery types.

– Gel

They’re usually slightly more expensive than lead-acid batteries because their chemical composition is different and requires less maintenance. They are more affected by temperature changes than lithium-ion and lead-acid batteries.

What can you run with a 100-watt solar panel?

The answer to this question can be a bit tricky. The general response seems to be, “it depends”. 

The wattage of your solar panel won’t directly define what you can run or not on your installation. It’s your inverter. Since you can’t directly use the electricity generated by your solar panel, your inverter will be your main limiter to your electricity consumption.

For example, if you have a 3000W inverter hooked to a 100Ah lithium battery that you charged with your 100watts solar panel, then your limit is 3000 watts and not your 100-watt solar panel. 

But as a general rule of thumb, a 100-watt solar panel can power a few small devices with a suitable solar controller and battery setup. For example, you’ll be able to charge your laptop (about 70-90watts), phone, and other small appliances.


A 100w solar panel is an excellent option if you don’t have a lot of space on your roof and don’t need that much electricity. If you have a lot of sun in your area, it can work well. I would recommend setting it up with a great battery bank that has a good capacity and will allow you to store more energy than you need if anything happens. I won’t go for less than 60Ah of a lithium battery bank. Good batteries are always a good investment. If you’re looking for a 100w ready-to-install solar kit, I would recommend you the Renogy 100-watt Starter Kit.


As an independent traveler, I try to share my positive and negative observations about van life as well as tips and tricks to make your life on the road easier. I travel and work in my old RV and would greatly appreciate a coffee from you if you find my content useful.

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