Solar panels are like lizards, they love basking in direct sunlight.
It’s hardly surprising either, as I’m sure you know, a solar panel works by absorbing photons of sunlight and converting them into electricity.
In fact, solar power is the most abundant energy source on Earth and is cheaper to harness than any fossil fuel option including natural gas.
But it is not without its own problems when it comes to reliability. When there’s no sunlight available, electricity grinds to a halt…
The best performance only arrives with direct sunlight, although you might be surprised to know that solar panels can still work when covered in shade.
When installing solar panels, it’s critical to understand the effects of direct sun and shade to get the best performing outcome.
Keep reading to find out the efficiency of solar panels in direct and indirect sunlight. In addition, we’ll look at how to ensure you get the outcome you’re looking for with your solar array.
Do Solar Panels Need Direct Sunlight to Work?
No, solar panels do not need direct sunlight to generate electricity. Any type of sunlight is enough to kick start electricity production. Even artificial light is able to transfer a little energy into a solar cell.
That doesn’t mean all light is equal, and direct sunlight is the only way to get the most efficient output.
Happily, direct sunlight doesn’t account for all of the energy absorbed by solar cells. Sunlight on Earth is broken down into two different categories – direct light and diffuse light.
Direct light is when there is no obstacle between the source and the final destination. In this case, the sun and the solar panel.
Diffuse light is when rays of light travel in different directions. This is the sunlight which creates the blue hue in the sky. This effect is created when the light is deflected and reflected around in the atmosphere. Or when obstacles, like trees, create shadows on Earth.
When it comes to solar power, about 30% of the absorbed energy actually comes from diffuse sunlight.
So what can we learn from this? Well, it’s clear that even when a solar panel is not in direct sunlight it still works. Although, performance will drop significantly often by 70% or more.
For example, a 100 watt solar panel performing optimally in peak sunlight can generate 100 watts. Remove the direct sunlight with shading at the output can drop to below 30 watts.
So, do solar panels need direct sunlight to work? No, but it makes a big difference!
What If You Can’t Install Solar Panels in Direct Sunlight?
Now you’re probably starting to get concerned if you don’t have an area that receives a lot of direct sunlight.
You should start to think deeply about whether solar panels are the right option for you. Especially if you are going to be investing a lot of money.
If you have a rooftop that seems to be heavily shaded then it’s best to try and rectify the situation.
You should look to remove any trees or obstacles that can create shading on solar panels.
Another helpful option is to add an energy storage system like deep cycle batteries. This will help you to take full advantage of times when direct sunlight is available and store the electricity for later.
When you don’t have direct sunlight available for your panels the efficiency and size of your solar array becomes even more critical. The more efficient the solar cells the more electricity you will generate. Monocrystalline cells will give you the best performance in this respect. Adding to this, increasing the size of your system will further increase power output.
Finally, you should be aware of the orientation required to access direct sunlight – hint, towards the Equator. For example, in the USA it’s best to face solar panels South rather than North. So start by identifying South facing areas for your installation.
Do Solar Panels Work in the Shade?
Yes, solar panels do work when they are shaded but performance is significantly reduced even if only a part of the panel is covered in shade.
The way solar panels are built means that every solar cell is interconnected. And when the current drops on one area, the whole panel reduces to this power output.
In fact, if you have solar panels connected in series, shading on a single solar panel can reduce the performance of the whole system.
This makes even partial shading a problem for solar panel performance. While they still work the efficiency takes a hit.
Fortunately, there are certain things that can be done to help alleviate the problem caused by shading on solar panels. Firstly, bypass diodes are included as standard to help eradicate a sensation known as hotspotting.
The introduction of optimizers and microinverters also now help to reduce the effects of partial shading across solar arrays.
Does Cloud Cover Stop Solar Panels Working?
No, cloud cover has a very similar effect to shade and usually results in complete shading across the solar panel. As we know, this doesn’t mean no sunlight is able to reach your cells.
If light couldn’t pass through could then we’d be left in complete darkness. What we are left with is softer diffused sunlight. This essentially means fewer photons of sunlight are traveling through the cloud cover to the ground. And fewer photons means less energy for your solar panels. Generally, you will find a solar panel only performs at 20 – 30% on a cloudy day.
How Much Direct Sunlight to Make Solar Panels Worth It?
You don’t need to live in the middle of a desert to make solar panels worth the investment.
Even in cloudy areas, such as Portland or Columbus, you’ll still see rooftops littered with solar systems. This free electricity production isn’t reserved for the sunbabies of LA or Miami…
There is no specific amount of sunlight that makes solar panels worth it. The best-case scenario is to receive 4 to 5 hours of direct sunlight between the hours of 10am to 3pm. These are known as ‘peak sun hours’ and deliver the highest electricity production.
If you often get less than this then it doesn’t mean solar is a waste of money. Particularly if you live in an area with expensive utility rates. Being able to save on hefty energy bills helps to reduce the payback on your investment. And once you’ve recouped the money you paid upfront, everything after this is completely free electricity.
For example, an area like Massachustes receives only 3 to 4 hours of peak sunlight a day but big savings allow a system to be repaid in around 3 years. Considering a solar panel lasts at least 25 years, that’s got to be worth it.
5 Tips for Increasing Sunlight to Your Solar Panels
If you’re worried about the amount of sunlight hitting your solar panels then here’s the most important factors to help increase performance.
Remove Light Blocking Objects
Your first job is to make sure there is nothing creating a shadow over your solar panels during the middle of the day. A professional installer should be able to advise and help with this.
The most common cause of shading is trees. Try to remove any branches that block the sunlight. Plus, think about the changing of the seasons as this will change the position of the sun in the sky. Trees will also put out more leaves in the spring and summer.
And don’t forget to keep the face of the solar panels clean. Regularly remove any dirt, dust, debris, and leaves that build up. Anything obstructing sunlight hitting your solar cells will dramatically reduce performance.
Orientate South
The best way to point solar panels is towards the equator. In the USA and UK that means South, while in Australia and New Zealand that’s North. Unless you live on the equator, the sun never sits central in the sky so you need to account for this movement. You can also get away with East and West facing although performance will drop 10% – 20%.
Orientating in the wrong direction will have reduced results and is a big mistake. For example in America, mounting solar panels on a North facing pitch of a roof. In the worst case scenario, this results in a complete loss of direct sunlight.
Optimal Tilt Angle
Solar panels are most efficient when tilted directly towards the sun at an angle of between 30 – 45 degrees. This is particularly important when mounting them on a flat roof or surface. You will always see solar panels on a flat roof mounted on a tilt bracket, almost like an artist’s easel. This ensures the solar cells are hit with the full force of sunlight.
Increase System Size
If we are lacking in direct sunlight the most effective thing you can do is to increase the amount of solar panels. This helps to generate more electricity even in poor light conditions. So if you live in an area with cloudy or adverse weather then this is an effective option. Of course, this will cost you more money up front but the savings on energy bills usually make it worth the investment.
Choose Monocrystalline Cells
In my opinion, it’s always worth choosing solar panels with monocrystalline cells. These are the most efficient types and deliver more than 21% conversion efficiency. In simple terms, it enables you to generate more electricity per square foot. Although they cost more initially, you will save more in the long run. This efficiency is even more pronounced in cloudy or shaded areas where you need to maximize performance.
Trying to save a few dollars with polycrystalline solar cells will generally cost you more in the long run as you fork out for energy bills.
Final Thoughts on Direct Sunlight for Solar Panels
It’s not uncommon to worry about the amount of direct sunlight your solar panels will receive.
In fact, once you start researching it can open up a can of worms.
To be honest, I wouldn’t advise mounting them in areas that receive zero direct sun.
But if the shading arrives due to cloud cover or long shadows in the morning and evening then it’s not a problem.
Solar panels will still generate electricity when in the shade. Performance will take a hit and you’ll only see 20% – 30% power compared to direct sun.
If you live in a particularly cloudy area then consider adding extra solar panels to give yourself a boost on the bad days. Plus, you’ll be turbocharged to make up for losses when the sun does shine.
