How Much Solar Power to Run a Computer

A power outage is a risk to anyone who works from home. As you prepare for an emergency or power outage you can charge up your laptop and other devices. what about your computer? A computer relies on AC power to run, a UPS can only keep it running for a while. You need a complete backup system in order to run it. 

In this article, we look at how much solar power you need to run a computer and set up a back system to run it for a few hours. 

Solar Power for 200-watt Computer

The most important factor in choosing the right solar power is to match the supply to the wattage of your computer. How much power a computer needs depends on what components are inside your computer, including the processor, graphics card, and hard drive. 

Older models used up to 300 watts and the new high-performance desktop computer use around 200 watts of power. So how much solar power will you need for a 200-watt computer? 

To run a 200-watt computer you’ll need two 100-watt solar panels, a 100Ah lithium battery, and an inverter rated at least 300 watts. 

We take you through the numbers.

Computer Watt-hours requirements

Electrical energy is measured in Watt-Hours. The length of time the computer operates determines how much power it uses.

Watt-hours take into consideration the number of hours you will be running your Computer. 

To calculate Watt-Hours you multiply the Wattage of the device or appliance and multiply by the number of hours you use the device. 

Watt-Hours = Watts X Hours 

If you want to use a computer for 1 hour, you will need 200 Wh of energy. This is almost the same energy consumption as a refrigerator.

This number will help us determine how many solar panels we’ll need and the number of batteries as well. 

How Many Solar Panels for a Computer 

Solar panels are made up of many solar cells, which convert sunlight directly into electricity. The size of the solar array and the output is dependent on the area, altitude, and how far you are from the equator.

The amount of solar energy that reaches any point on Earth is affected by:

The angle at which sunlight strikes a surface (the higher it is in the sky, the greater this angle is).

The time of day — solar radiation peaks during the summer months when there are more hours of daylight than at other times of the year.

Cloud cover — clouds can block or reflect sunlight depending on whether they are made up of water droplets or ice crystals (which reflect light).

We use a ballpark figure of 4 sun hours to round off for cloud cover and efficiency. In an area that receives around 4 hours of sunlight a day, you will divide the total Watt-hour requirement by this number. 

200Wh/4 = 50 Watts 

Again we double this again to increase efficiency to 100 Watts.  A 100-watt solar panel is more than enough to power a computer for 1 hour however it is not the determinant, you’ll need a battery that will power your device via an Inverter. 

What Size Battery to Run a Computer

From the example above we’ve seen, we’ll need around 200 Wh in order to run a computer for 1 hour a day. 

In order to get the size of the battery, you would need to run the TV you will need to convert the Watt-hours to Amp-hours. This is how most batteries are rated. Amp-hours is 1-amp of power expended over one hour. 

To calculate Amp-hours you divide the Watt-hours by the voltage. The voltage in a battery bank is usually between 12v and 24v depending on how you wire the system. 

200Wh/12v = 16.67 Ah 

200Wh/24v = 8.33 Ah 

You’ll need a battery bank that can support 17 amps in one hour for a 12v system and 9 amps for a 24v system.  

Solar batteries are recommended to be discharged at 0.2C or at 20% capacity. So for 17 amps, you’ll need an 85Ah battery. This battery can last up to 5 hours with the computer.  But in order to reserve capacity, you should use a battery of at least 100Ah. This is enough to last for 5 hours. 

Our 100-watt solar panel will provide around 10 amps to recharge the battery in 10 hours. A 200-watt solar panel can add up to 20 amps recharging the battery in 4 hours (or more depending on sunlight availability). This will allow you to use the computer for over 10 hours. 

Inverter for 200-watt computer

An inverter converts the DC power from the battery to AC power that your computer can use. You will need a minimum of 300-watt inverter in order to run your computer. You can go up to 500 watts with your inverter to support other appliances with your computer. 

ApplianceWattage (Watts)
Desktop Printer50
Wi-Fi Router10

The battery will easily support these other appliances with no issues however this might reduce the amount of time it will take. 


Depending on the amount of power drawn from your computer’s electrical supply, you may be able to meet your needs by relying on solar power. As we saw above, a single 100-watt panel can alone provide the juice for a standard desktop tower all day. Of course, that assumes you have a small efficient enough computer to run with this little energy.

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