What Size Inverter Do I Need for a 100 Watt Solar Panel

Updated: July 11, 2023

A 100-watt solar panel installation is a great way to ease into the off-grid solar game, which is why they are popular with homeowners, solar enthusiasts, and in RVs

Before implementing your 100 watt solar panel in your off-grid property, you need the right equipment and setup.

We are here to tell you all about inverters, and what capacity inverter would work for a 100-watt solar panel. You will also find a quick and easy guide for calculating what size inverter you need, and different types of inverters.

 You will also find out which batteries and solar charge controllers you will need, and exactly which AC appliances can be powered with a 100-watt solar panel.

Finding the Right Inverter for a 100 Watt Solar Panel

Inverters are devices that allow your AC (alternating current) home devices to be powered by solar panels.

What Capacity Inverter Should You Get?

To figure out what capacity inverter you will need for your solar setup, you will need to calculate your power needs. Calculate the watts and amps that you want to run.

You need an inverter with a capacity that is around 20% higher than your largest power output. Your 100 watt solar panel specifications and calculations are important.

Generally, a 12v DC to 220v AC, 200-watt inverter would be able to run your AC-powered appliances with a 100-watt solar panel.

Your 200-watt inverter can run a continuous supply of power to AC electricals like printers, coffee makers, lights, laptops, game units, blenders, and small TV sets, with a 100-watt solar panel.

Calculating Inverter Size

Calculate Power Output of Solar Panel in Watts

To calculate what capacity inverter you need on your own, you would need to know how many watts per day are produced by your solar panel.

A 100 watt solar panel that receives 6 hours of sunlight will produce 100 x 6 = 600 watts per day.

Calculate Capacity of Battery

The next step is to calculate the size of the battery you will need because that is where solar power goes. Your inverter draws power from your battery to run AC appliances.

When a solar panel charges a battery, around 15% of the energy may be lost. Thus, if the solar panel is 85% efficient the battery will receive 600 x 0.85 = 510 watts.

Let us suppose you have a 12V battery and it is 50% charged. To fully charge the battery you need 510 x 2 = 1020 watts.

Now you need to convert 1020 watts into amp hours. The calculation would be W / V = A.

1020 watts / 12V = 85Ah.

This means that an 85Ah battery will do the job with a 100 watt solar panel and 12V battery. 

But, 100Ah batteries are more common and would also be the most suitable option.

Calculate Size of Inverter

You now know the size of your battery. Now you can figure out which inverter to get.

Inverters should have a capacity that is at least 25% to 50% greater than the total wattage required.

The maximum power output of your solar panel is 100 watts per hour. This means that the inverter needs to be 25% to 50% bigger. This amounts to an inverter with a capacity between 125 and 150 watts.

Doubling the wattage is also a safe bet. A 200-watt inverter would also work perfectly, and they are more common on the market.  

Types of Inverters

Inverters produce different types of wave outputs. The three most common types of inverters are pure sine wave, modified sine wave, and square wave.

Modified Sine Wave Inverters

This is an older and less expensive type of inverter. These inverters work well with most equipment. But, they may cause problems with some delicate electronics.

The power or efficiency of some equipment may be reduced by a modified sine wave inverter, or equipment may run hotter than usual.

You may experience problems with fluorescent lights, digital clocks, fridge motor pumps, fans, speed drills, light dimmers, and bread makers.

Pure Sine Wave Inverters

Pure sine wave inverters are a better investment than modified sine wave inverters since they are more versatile.

Most of the equipment and electronics on the market are designed for pure sine wave inverters, and your electronics will work according to their specifications.

Appliances like microwave ovens and motors will only reach their full power output with these inverters. LED televisions, battery chargers, fluorescent lights, and laptops will run smoothly with these inverters.

Square Wave Inverters

Very few square wave inverters are seen on the market today.

Square wave inverters can run simple appliances like universal motors, but not much else.

Why Do You Need an Inverter for a 100 Watt Solar Panel?

Inverters convert the DC (direct current) flowing from your battery into AC so that you can power AC home appliances with your off-grid solar setup.

The power that runs through the main power grid to supply homes with electricity flows in AC. Home appliances use AC to run.

On the other hand, the batteries connected to your solar setup flows in DC. Therefore, inverters have to convert DC to AC in order to power your home appliances with solar power.

Other Equipment Needed to Run Your 100 Watt Solar Panel Setup

You would need to know what gauge wire for 100 watt solar panels is suitable for your set-up, and find compatible equipment.

Batteries

Batteries are essential for your solar setup because they store excess electricity to use when needed. 

Without batteries, your inverter would not have any use. Inverters convert DC power flowing from batteries into usable AC power.

Why do you need batteries?

Batteries do not let excess electricity go to waste. Off-grid solar setups do not have access to the main power grid where you can import and export electricity to suit your power needs.

That is why your off-grid system needs batteries to store the electricity you did not use. This way, you will not be left without power during the night or on cloudy and overcast days.

What Capacity Batteries Do You Need?

The bigger the capacity of your battery, the more electricity you can store. Your battery should have the capacity to store at least twice the daily power output of your solar panel. 

With many options on the market you may wonder: How many batteries do I need for a 100 watt solar panel? What capacity battery do I need?

With a 100 watt solar panel, you could use one 85Ah 12V battery.

But your best option would be to use one 100Ah 12V battery.  

If you want to make your battery last long you should avoid letting the battery reach 50% discharge.

Solar charge controller

Solar charge controllers regulate the power flow and voltage in your solar installation, including the flow of current between batteries and solar panels. They are vital to your solar setup.

Solar charge controllers manage current, run electrical loads, and charge batteries. They protect your solar installation against shorting, overcharging, and damage.

They cannot be left out. You would need an inverter and a solar charge controller to run an off-grid set-up that works with DC current flowing from batteries.

Why do you need an inverter and charge controller? Keep in mind that your battery provides the power that your charge controller regulates in the first place. Without an inverter converting the DC power from the battery into usable AC power, your charge controller would not work. 

What Size Solar Charge Controller Do You Need?

If you are looking to complete your solar installation, you may be wondering: What size charge controller do I need for a 100W solar panel?

A safe option for a 100W solar panel with a 12V battery bank would be to get a 10 amp charge controller. 

Power Output of a 100 Watt Solar Panel

Watt-Hours

The power output of a solar panel depends on the amount of sunlight, the angle of the solar installation, and heat build-up.

You should preferably find out how to install a 100-watt solar panel set-up so that it gets as much sunlight as possible.

If your 100 watt solar panel receives 4 – 6 hours of peak sunlight per day, it can produce around 400 – 600 watt-hours over 24 hours.

During the winter and on cloudy days your 100 watt solar panel may produce around 80 – 100 watt-hours over 24 hours.

If you want to increase the output of your system you will need to know how to connect 2 100 watt solar panels or more.

Amp-Hours

A 100 watt solar panel will be able to produce 5 or 6 amps per peak sunlight hour. A rule of thumb is that a 100 watt solar panel can produce 30 amp-hours per day.

Under perfect conditions, a 100 watt solar panel will produce 5.5 – 6 amps per hour of sunlight. This is called the “maximum current rating.”

In reality, your solar panel would produce 50 – 100% of the power of the maximum current rating.

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Did you find our blog helpful? Then consider checking:

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• 500 Watt Solar Panel System
• DIY Solar Panel System Installation Guide
• 1000 Watt Solar Panel Systems
• What Equipment You Need for a Complete Solar Panel System?
• 60-Cell vs 72-Cell Solar Panels
• How Long Do Solar Panels Last?
• Top 4 Grid-Tie Inverters Definitive Buyer's Guide