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How Much Less Efficient are North-Facing Solar Modules?

Experts agree that south-facing orientations are best for most solar installations in the Northern hemisphere, but what if that isn’t an option? Is solar still a viable solution if a solar array can only be installed in a north-facing direction?

That depends. In the Northern hemisphere, solar panels receive more sunlight if they face south than north. How much less efficient a north-facing solar module is than a south-facing module will depend on a number of factors, including the pitch of the roof and the area of the country where the modules are being installed.

Many property owners—both commercial and residential—have found great success mounting solar modules in north-facing positions. In this article, we will explain more about how solar modules work to produce energy, and how a solar engineer can help you determine the best placement for panels on any structure.

How Solar Modules Work

A solar module, or solar panel, is a single photovoltaic panel. Nearly all solar modules are set up in arrays, or groups of modules. Solar modules consist of an assembly solar cells. These solar cells absorb sunlight as a source of energy. Solar modules are one of the most effective tools we have for generating electricity that can be used to supply power to all types of buildings.

The size, shape, and slope of a space are important factors to consider when installing solar modules. Solar panels installed along rooftops perform best when roofs are south-facing, with a slope of 15 to 40 degrees. However, many other spaces may also be suitable for solar panel installations.

What Makes a Solar Module More or Less Efficient?

The efficiency and wattage output from a solar cell will vary depending on a number of factors, including the type of solar cell and the quality of the solar cell.

The average solar module ranges in energy production from 300 to 550 watts of DC electricity.

Any number of factors can impact the energy output of a solar module. A high-quality module sold by a reputable firm will almost always generate more electricity in a more efficient manner than a lower-quality solar module.

Certain aspects of a building’s design will impact the efficiency of a solar module, as well. For example, the pitch of a roof can have a major impact on efficiency. In certain settings, such as when a building has a very steep roof, a north-facing solar module may never get direct sunlight. In these situations, a solar engineering specialist would need to assess the situation to look for a remedy.

Can North-Facing Solar Modules Generate Electricity?

When designed by a qualified solar engineer, north-facing solar modules can still be an effective solution for generating electricity. While they won’t generate as much power as solar cells pointed directly at the sun, north-facing solar modules can still produce power on clear days.

North-facing modules can be added on to an existing system to make the existing system more profitable. As a rule of thumb, north-facing modules within 10% of south-facing modules are likely to be profitable. In these cases, adding north-facing modules to an existing system involves only marginal costs, such as installation labor and hardware. Fixed costs, such as permitting, would not be increased when installing additional solar modules in a north-facing direction.

How is it possible that a north-facing module can still be efficient when connected to a south-facing module, even if it isn’t directly facing the sun? The answer has to do with diffuse sunlight, or the “glow” of the blue sky. While north-facing solar modules rarely get direct sunlight, they can still be set up in a way that benefits from diffuse sunlight. Diffuse sunlight accounts for roughly 30% of energy from the average solar array.

Additionally, there will almost always be some period of time during the summer where the sun is directly overhead. During this period, all arrays will be productive, regardless of whether they are facing north or south.

The differences between north-facing and south-facing solar modules will be more pronounced during winter months. However, overall energy yield is typically smaller during those periods, regardless of which direction a module is facing.

Investing in solar modules will often be worthwhile, even if the module must be installed in a north-facing direction. In these cases, it is best to consult with a solar engineer for precise information on how efficient a particular setup may be.

Are Bifacial Solar Panels a Solution for North-Facing Setups?

Bifacial solar panels produce power from both sides of the panel. Unlike traditional monofacial solar panels, bifacial solar panels expose both the front and backside of the solar cells. This makes bifacial solar panels a uniquely efficient solution.

Bifacial solar panels are considered to be more durable than traditional monofacial solar panels because both sides are UV-resistant, rather than just one. Degradation concerns are reduced in these systems, as is the time required to recoup investment costs.

With bifacial solar modules, more power can be generated in a smaller footprint. According to the U.S. Office of Energy Efficiency and Renewable Energy, bifacial solar panels have the potential to increase system outputs by 10% to 20%.

KMB: Solar Engineering Consultants