How Much Power Does a Solar Panel Produce?

If you are considering moving to solar power, you are likely asking yourself, “How much power does a solar panel produce?”

It’s an important question that will help you decide what size solar system you will need to meet your energy requirements. It is also a factor in the price, which is determined in part by the kilowatt’s DC (kW) of the system.

How Are Solar Panels Made to Function?

It seems like it should be a simple math equation.

If a solar panel is 3 1/4 feet by 5 1/2 feet and its rating indicate that it produces 360 watts, then it seems reasonable to assume that each square foot should produce roughly 20 watts, but not so fast.

The real test of the solar panel system is how it performs in real-life conditions.

If your solar panel is going to produce the maximum power per square foot, it needs to be designed well enough to account for temperature, spectrum, angle, and amount of light, as detailed below.

Temperature

Because solar panels operate with sunlight and most people associate sunlight with heat, it is often thought that solar panels require heat as well as light.

In truth, when the temperature climbs too high, the solar panels may lose some of their efficiency. Past 77°F/ 25°C, you will almost assuredly experience a drop-off in power production.

You will want panels that are designed to minimize these losses, reducing the impact on energy production.

Spectrum

It’s pretty much a given that you are going to experience cloudy days, but this doesn’t mean that your solar panels are going to stop working when the sky is overcast.

There is a wide spectrum of light and only a portion of it is visible to the human eye. Some light, like ultraviolet or infrared, is invisible to us.

Although clouds appear to diminish all light, some parts of the spectrum get through.

Panels that efficiently capture infrared or ultraviolet light will have a significant advantage over those that don’t, allowing homeowners to use fewer panels while still meeting their energy needs.

Angle

You may have noticed that some homes seem brighter than others, even with fewer windows. Or perhaps one house has better luck growing flowers in the backyard than their neighbour across the street.

This is because of the orientation toward the sun.

Solar panels are typically installed facing south to aid in capturing the most direct sunlight possible. Despite this, sometimes the sun’s rays will hit the panels at a less-than-optimal angle.

For this reason, most solar panels are built with “anti-reflective glass.” This means that when light enters the panel, it will bounce back into the solar cell, allowing for the maximum amount of energy to be captured. This anti-reflective glass can degrade over time due to exposure to the elements. Those with a lower degradation rate will continue to function optimally for a longer period of time.

Amount of Light

The peak time for energy production is around noon, though your precise location will have an impact on this.

Other factors that can reduce the amount of light include shade from tall trees, leaves, dust, and other particles.

In fact, shade can do more than just reduce power production, actually causing damage to the solar panel over time.

Working With Solar Installers

Installers will do their best to ensure that the impact of shade is minimized.

Highly efficient solar panels can also allow homeowners to use less roof space, meaning they won’t need to be installed in shady spaces.

Because of these variables, it is difficult to know exactly how many square feet of your roof will need to be covered in solar panels.

At 20 watts per square foot, a system that is rated to produce 2 kilowatts would cover about 150 square feet. A 3kW system, however, would require closer to 225 square feet.

Installers have specialized software to help them determine the power needs of your house while factoring in typical weather patterns, roof angles, and more. This lets them know how many panels you will require and the amount of power you will be able to generate per square foot.

When installing solar panels, aim for a system that provides the greatest amount of power that you can afford, or the most that can fit on your roof. The more energy that you can produce, the quicker you will pay off the system, allowing you to save the maximum amount of money.