Best Inverter For 100Ah Battery (+ Calculations)

A 12V 100Ah battery has a 1,200 Wh (Watt-hours) energy storage capacity. It will be able to theoretically power a 100W lightbulb for a maximum of 12 hours if the battery can be discharged to zero percent depth of discharge (DOD).

You would thus typically need a 150W inverter to power the 100W light bulb from a 12V 100Ah battery.

The best is the Victron Phoenix Compact 1200VA – 2000VA for over a thousand dollars. First, determine which AC loads you wish to power to determine the correct size solar panel, battery bank, and inverter to purchase.

Determining the size and type of inverter to install is dependent on the following factors:

AC power demand required per day in Watt-hours
Size of battery bank required to store the number of days power capacity
The size of the solar panel array needed to recharge the battery bank fully
What is the maximum power demand each day

Let’s look at determining the best inverter type and size for your application.

Housing and casing on a wall for a solar inverter being prepared

What Is The Best Inverter For A 100Ah Battery?

I would advise you to buy the Victron Phoenix Inverter Compact 1200VA – 2000VA. The Phoenix Inverter Compact is a pure sine wave inverter with high efficiency. It is developed for professional duty and is suitable for a wide range of applications.

Victron is regarded as one of the US’s best and most user-friendly solar power components companies. I would be doing you an injustice to allow you to go and purchase this inverter without questioning what you need the inverter for.

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Asking the question “What is the best inverter for a 100Ah battery?” is the same as asking, “What is the best car to use up 100 liters of fuel?”

You need to know what you want to do with the energy. How many appliances do you wish to power from the inverter and battery bank?

Let’s pursue what’s best for you – Battery energy storage capacity is expressed as the duration in hours for which the battery can supply 12V or power at a given current draw in Ampere (A). For example:

A 12V 100Ah battery has a maximum battery energy storage capacity of 12V x 100Ah = 1,200Wh or 1.2 kWh (kilowatt-hour).

You measure the energy usage of your car in the liters of gasoline or diesel used per month. Your household energy usage is measured in kilowatts or kilowatt-hours per month.

30kWh PV Array Example: Batteries + Inverter

Your monthly utility bill is based on the number of kilowatt-hours of power drawn from the power grid. The typical US household uses 30kWh of power per day to satisfy the power demand.

The bulk of the 30kWh is consumed during the 4 pm to 8 pm peak usage hours.

You would thus need to buy 30kWh / 1.2kWh = 25 batteries with 12V and 100Ah of storage capacity.
However, if you buy 25 sealed lead-acid (SLA) batteries of 12V and 100Ah, you will only have 15kWh of power available as these batteries cannot be discharged lower than 50% depth of discharge (DOD).

You would need to invest in Lithium-Iron-Phosphate (LFP) batteries that can be discharged to 0% DOD.

You would have to purchase solar panels to enable your 30kWh battery storage bank to be charged back up to 100% during the five solar productive hours per day.

The size of the solar array will have to be 30kWh / 5 hours = 6kW or 6000W.
If you buy 400W rated solar panels, you will need 6000W/400W = 15 solar panels to generate the required minimum of 6000W during the five productive solar hours per day.

Now you can focus on the size and type of inverter needed to convert the 30kWh of stored power to the AC power needed to power your household appliances and lights.

A household with daily consumption of 30kWh or energy will typically use a 6,000W pure sine wave inverter to power the household AC loads.

You still cannot run all the AC appliances in your household simultaneously as you cannot exceed a power draw exceeding 6000W at any point during the day.

The inverter can deliver 6,000W of power for short periods, but it is recommended not to run an inverter at maximum output for extended periods.

Ideally, the inverter loading should be at 80% of the maximum rated output capacity to ensure a long lifespan.

What Can You Run On A 12V 100Ah Battery And Inverter?

A 12V 100Ah battery can store and deliver 600Wh if it is a lead-acid type battery (50% of 1,200W) and 1,200Wh if it is a Lithium-Iron-Phosphate type battery.

Assume you want to run a 120W computer for a minimum of five hours per day. You would need to draw 120W for 5h = 600 Wh to run the computer and use an inverter with a maximum output rating of 150W.

The 1,200Wh of an LFP battery will give you two days’ worth of autonomy, while the lead-acid battery will only power the computer for one day before needing to be fully recharged.

Refrigerator

You can run a 600W refrigerator for one hour on a lead-acid 12V 100Ah battery but will need a 750W inverter to convert the direct current from the battery to the alternating current required by the fridge. The LFP battery will run in the same fridge for two hours.

UPS

A 12V 100Ah battery only has sufficient energy storage capacity as an Uninterrupted Power Supply (UPS) for small loads such as PCs, laptops, printers, cell phone chargers, LED lights, and WiFi routers.

125% Of Your Demand

It would be best to calculate the sum of the power demand (Watt) of all the devices and appliances that you wish to run off inverter power if the grid power is interrupted.

Select an inverter with a maximum rated output capacity sufficient to power 125% of your calculated power demand.

The power conversion from DC to AC is not done at 100% efficiency, and you thus have to allow for the inverter capacity to be at least 25% above the full power demand of all your AC loads.

Large inverters can easily power small loads, and it is better to invest in a 1,000W inverter to give you options to expand your battery storage capacity and AC loads. Look at modular expansion in the design of your off-grid power system.