Can you install solar panels if your roof is shaded?

Yes, you can install solar panels even though your roof is shaded.

The reason is, even though your roof is shaded there is still sunlight available. Your solar panels do not require direct sunlight to work, but the efficiency will be less.

When installing solar panels your solar provider will analyze the shading impact throughout the year and will let you know whether this is a good investment or not. So getting the service from a qualified solar provider is very important.

What causes roof shading?

Roof shading is commonly caused by trees. But if you are living in a more urban area, then the shading can be caused by neighboring buildings or any other manmade structures.

Also, shading can cause by structures like chimneys, AC units, etc which are on the roof.

According to your geographical location, the most suitable orientation for your solar panels will change. By facing this optimum direction you can get the most of the sunlight available during the daytime.

If you are living in the northern hemisphere, by facing your solar panels to the south you can get the most of the available sunlight throughout the day. If you have any plantations or any structures to the south then these will block most of the sunlight.

If you are living in the southern hemisphere, by facing your solar panels to the north you can get the most of the available sunlight throughout the day. If you have any plantations or any structures to the north then these will block most of the sunlight.

If your structures are not much tall and do not block the sun’s path, then even though they are in the above-mentioned direction it will not be much of a problem.

But the sun is not at the same level throughout the year. Especially in winter, the sun will go down. So the trees or other structures can easily block the sunlight.

When installing solar panels you have to analyze the availability of sunlight throughout the year. For that many solar installers use tools and software to check the sun’s path related to your location and will analyze the amount of sunlight that your roof gets.

How to estimate the shading impact?

To estimate the shading impact solar installers use different tools and software. Most accurate tools can be really expensive, so purchasing such tools and software on our own is not easy. Also, investing a large sum of money in a tool that you are going to use only once or twice is not a wise decision at all.

These tools can easily collect the data on the sun’s level, path, etc. and the software will analyze them and provide the information about shading. Some software even offers you 3D data and allows 3D simulation for more accurate planning.

Some software uses satellite images and data available on the database to give more accurate data.

Some tools available;

• SunEye
• Solar pathfinder
• HORIcatcher
• Steprobotics

Some software available;

• Shadowanalyzer
• pvPlanner
• Autodesk ECOTECT analysis
• Shadow analyzer
• METENORM

How does roof shading affect the efficiency of a solar panel?

Shading decreases the efficiency of a solar panel.

To generate power, solar panels need the energy of the sunlight (read more). When sunlight hits the solar panels it absorbs the energy of the sunlight and produces free electrons which contribute to the output voltage.

When the roof is shaded that means the part of the sunlight your roof gets will block. So this will reduce the amount of sunlight your solar panels get. So the energy that absorbs into the solar panels also will reduce. This will decrease the number of free electrons that are produced and will decrease the output voltage.

Can solar panels generate power at all if they are shaded?

Yes, they can

As we mentioned earlier, even though solar panels are shaded still they can work under low light conditions. Especially the monocrystalline silicon panels can work in low light conditions as they have higher efficiency.

Also, solar panels have bypass diodes which are also called free-wheeling diodes. They are installed by the manufacturer, either in the module junction box or integrated into the module itself. These bypass diodes will help the flowing current, to bypass solar cells that are shaded or faulty. These bypass diodes are in parallel with the solar cells.

By having bypass diodes it will help to protect the shaded solar cells in solar panels from overheating and also to improve the final output of the solar panels.

So because of the bypass-diodes solar panels can produce power even if it is partially shaded.

But sometimes having bypass-diodes is not enough;

• If the panels are shaded heavily the output voltage of the solar panels can drop below the minimum voltage allowed by your inverter (inverter is the component of the solar system that converts the DC output voltage to AC voltage).
• There can be some instances that shading is not enough to activate the bypass-diodes. In this case, bypass-diodes will not work properly. So the final output of the panel will decrease because of the lower outputs of the shaded solar cells.

For instances like this, you need Module Level Power Electronics (MLPEs). These devices work at the module level. They will be attached to individual modules and increase the performances of the shaded modules by tracking the maximum power point at the module level.

Available MLPEs are;

• Microinverters
• DC optimizers

Microinverters and DC optimizers

Microinverters;

Instead of using one traditional inverter for all solar panels of your solar system, micro-inverters will be fixed on each panel. So the DC output voltage of each solar panel of the system will convert to AC separately.

Because of these microinverters, the decreased outputs of the shaded panels will not affect the performance of the other solar panels.

These microinverters also allow you to monitor your solar panels at the module level.

DC Optimizers

Same as the microinverters, DC optimizers are also fixed to each panel separately. So each panel works separately and does not affect the performance of other panels. So the underperformance of the shaded solar panel does not affect the performance of other panels.

Also, DC optimizers will help to maximize the performance of the panels. Also, these will help you to monitor your panels and even protect your panels from fire hazards.

What are the solutions, if your roof is heavily shaded?

If your house roof is heavily shaded and do not receive enough sunlight at any time of the year you can go for the following solutions;

• You can install your solar panels on a carport, garage, or on any other roof with enough roof space. But this can be relatively expensive as most of the time, they need roof material replacements to strengthen the roof to hold the panels. (Read more – can your roof hold your solar panels?)
• You can go for ground solar systems if you have enough clear ground space.