Do Solar Panels Need Direct Sunlight?

Do Solar Panels Need Direct Sunlight?

Solar panels function by absorbing the photons from natural sunlight and converting them into usable electricity. Therefore, the more sunlight they get, the better they perform.

However, what if you have installed your solar panels under trees? What if you live in an area that doesn’t get much peak sunlight? Maybe you live in an often rainy, cloudy, or snowy area. How will this all affect their electricity generation?

Many question whether solar panels need direct sunlight to function properly. The short answer is both yes and no.

Solar panels can function in indirect light, but not nearly as well as direct sunlight. Let’s take a closer look at this issue and provide tips on ensuring that your solar panels get as much direct sunlight as possible.

Solar Panels and Direct Sunlight

As mentioned above, solar panels are designed to absorb the sun’s photons and turn them into usable electricity. Photons are present in both direct and ambient sunlight. So, more photons will be available for absorption in direct sunlight than in indirect sunlight.

This means that solar panels that get lots of direct sunlight will produce more energy than those in indirect light. When the panels aren’t in direct sunlight, they will still produce electricity. However, direct sunlight is best.

So, solar panels do not necessarily need direct sunlight all of the time. They will still function in indirect and ambient sunlight, albeit their output will be reduced. This means that solar panels will still produce electricity on cloudy, rainy, and snowy days.

Optimum Conditions for Solar Panels – Peak Sunlight

One thing that needs to be addressed is peak sunlight hours. Don’t confuse peak sunlight hours with overall sunlight hours. For example, your house may get from 5 to 10 hours of sunlight per day, but that is not peak sunlight.

Peak sunlight is defined as a period of direct sunlight where an area gets at least 1000 watts per square meter; this is how many hours per day a solar panel can get 1000 W/m2. Therefore, panels need to be exposed to a certain amount of peak sunlight to maximize solar panel output.

Peak sunlight can only be achieved in direct sunlight. Therefore, if you expect to maximize solar panel output, they need to be exposed to direct sunlight.

Being shaded by obstacles or clouds won’t totally eliminate electricity production but will reduce it significantly. If you live in an area that gets an average of four hours or more of peak sunlight per day, you are in luck.

So, you need to know that to make your solar investment worthwhile, those panels should get at least four hours of peak sunlight, a total of 4000-watt hours of direct sunlight exposure per day. This should ensure that your solar investment is worth it.

Peak sunlight is essential, but that said, what if your solar panels don’t get at least 4 hours per day? Will your investment be worth it?

The short answer here is that likely, yes, it will still be worth it. For example, let’s say that your solar panels only get 3 hours of direct sunlight per day. Although that’s an hour short of the optimum level, they’ll still have anywhere from 5 to 10 hours of ambient or indirect light available to use.

Shade, Weather, and Solar Panel Output

So, we have established that solar panels work best in direct sunlight but can also work in indirect sunlight. That said, how will shade, clouds, snow, and rain affect solar panel efficiency and output?

Cloud Cover

Cloud cover is one of the things that you do have to worry about. Clouds obstruct a good deal of light and reflect some back upwards, away from your solar panels.

If there is heavy cloud coverage, you can expect solar panels to produce just 10% to 25% of their desired output.

Let’s use 25% for a quick example. If there is cloud cover, those solar panels will need about 4 hours of indirect sunlight to produce as much as they usually would in one hour of peak sunlight. As you can see, solar panels still work on cloudy days, albeit not nearly as well as in direct sunlight.

Shade

Shade tends to be worse for solar panels than cloud cover. Shade from a tree, other solar panels, houses, and more, will likely block out more sunlight than moderate cloud cover. While a bit of cloud cover is tolerable, having your solar panels partially or fully shaded is not good. The issue here has to do with the way electricity flows.

If one solar cell out of many is shaded, it will reduce the output of the whole system. So, if one cell out of 40 is shaded, it actually affects all 40 cells. A single shaded cell can reduce overall production by as much as 75%.

We can compare this to something like a blocked water pipe. If there is a blockage in one small section of the line, it reduces water flow through the whole pipe.

This is the same with electricity. If the flow is obstructed or reduced, it affects the system as a whole. In the section below, we will talk about a great way to get around this issue of panel shading.

Rain

If there is rain, there are clouds, and as mentioned above, cloud cover can reduce output by 75% to 90%.

However, rain itself is actually beneficial for solar panels. Rain helps clean solar panels of dirt and debris. Clean panels allow them to absorb as much sunlight as possible. So, while constant clouds and endless rainy days won’t do you any favors, an occasional rainstorm will.

Snow

We also need to account for a production decrease due to those snow-producing clouds. However, snow itself is not necessarily bad for solar panels either. Yes, a heavy snowfall that covers your solar panels will block out a good deal of light.

However, just a little dusting won’t make much difference. Moreover, snow reflects a lot of sunlight, so it could be beneficial if your panels have snow around them for light to reflect off. Moreover, keep in mind that there is more electron activity in cold weather, so solar panels typically absorb more photons in cooler rather than warmer temperatures.

How to Maximize Solar Panel Sunlight Exposure and Electricity Production

Let’s go over some tips on maximizing solar panel output, particularly in terms of sunlight exposure.

Avoid Shaded Areas

Positioning your solar panels correctly is essential. Make sure that solar panels are not blocked by houses, walls, trees, or other solar panels.

The Proper Position in Relation to the Sun

You also need to position your solar panels regarding where the sunlight comes from in your area. For example, if you are in the northern hemisphere, you’ll get your sun from the south. So the position of the solar panels in relation to your latitude makes a big difference.

The sun is not always in the same position. For instance, in the summer, the sun is directly overhead a lot, whereas, in winter, it’s often at an angle. This means that the way your solar panels are pitched or tilted matters.

In the summer, having a low tilt of 20 degrees is best (you want those panels facing almost straight up). However, to directly face the sun in the winter, you want those panels to have a 60-degree pitch. Therefore, a steeper tilt during the winter is best.

Sun Tracking Systems

Of course, getting a rotating solar panel mount is beneficial. These so-called solar tracking systems automatically follow the sunlight and automatically adjust the angle and tilt of the panels to catch as much sunlight as possible.

Bypass Diodes

In terms of shade, bypass diodes will come in handy. Remember that if one panel cell is shaded, it affects the whole panel and string.

A bypass diode lets the electricity from the unshaded cells flow past (bypass) the shaded cells. Bypass diodes allow the panels in direct sunlight to function at full capacity while remaining unaffected by shaded panels.

Conclusion

The bottom line is that solar panels work best in direct and peak sunlight. However, they still work in indirect and ambient sunlight.

Shading and cloud cover will reduce efficiency and output, but your panels will still work. If you follow the above tips, you’ll be able to maximize solar panel sunlight exposure, efficiency, and output.  

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Hi there! I'm Ally, I can help you find out if solar makes sense for your home in 30 seconds!

See if your home qualifies and how much you could save with current programs available...