When Are Solar Panels Most Efficient?

When Are Solar Panels Most Efficient

The idea of switching to solar energy is certainly appealing, especially in Australia where we’re getting more sunlight than most other countries. But, as you likely already know, power output from your solar panels can vary throughout the day. This brings us to the question:

When are solar panels most efficient?

I’m answering that and other related things shortly. Below is a list of topics that this article covers. Feel free to tap on any of the bullets to skip sections.

What time of day do solar panels work best?

Generally speaking, a study says that a solar system produces most of its solar power at around noon. This also means that panels are most efficient around that time.

This makes sense because light intensity is also at its peak at around 12 o’clock.

Now, I say generally because there are things other than time that can affect the efficiency and the power generated by your solar panels.

We’ll talk more about them later in the article but the orientation your panels were installed in, for example, can affect whether you get better efficiency in the morning or afternoon.

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What season do solar panels work best?

The time of year can affect how much direct sunlight there is available to for energy production (i.e. solar irradiance) which, in turn, affects the efficiency of solar panels.

That being said, the summer months are when the days are the longest and when your solar array gets the most direct sunlight. Thus, your solar panel’s efficiency will be at its highest during December to February.

On the other hand, winter is typically when you’ll see a noticeable dip in the power generation of your solar panel system.

However, do note that hot weather can also negatively impact the efficiency of your solar power system. Again, more on this later, but the hotter it gets, the less efficient your solar power panels could become.

Factors that can affect the efficiency of solar panels

Factors That Can Affect The Efficiency Of Solar Panels
An illustration depicting factors influencing solar panel efficiency.

Temperature coefficient

While we’re talking about hot weather lowering the efficiency of your solar system, the reason behind that is temperature coefficient – the reduction in solar panel’s efficiency, for every degree it gets hotter than 25℃

Most panels have temperature coefficients ranging from -0.3% to -0.5%. Now, let’s say for example that you have a solar module that has a 20% efficiency rating with a -0.5% temperature coefficient.

  • If it’s 25℃ outside, your module’s efficiency remains at 20%.
  • If it’s 26℃ outside, your module’s efficiency drops to 19.5%.
  • If it’s 27℃ outside, your module’s efficiency drops to 19%.

With that said Australia’s most efficient solar panels have better temperature coefficients than most. Be sure to consider them when choosing what goes on in your home.

Recommended: A guide to choosing your home’s solar panels

Orientation and tilt

For orientation (or where your panels are facing), a north-facing system is generally going to generate more solar energy than any other direction. That’s because Australia is in the southern hemisphere.

However, east and west orientations are solid options, too, if that’s where your roof is facing. They aren’t as efficient but they can still generate copious amounts of solar energy due to where the sun rises and sets.

For tilt, whatever pitch your roof has is going be to serviceable. Technically, though, the most efficient angle for installing solar panels will be equal to the latitude angle of your property.

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Shade is one of, if not the biggest enemy of a solar power system. “Why?”, you ask. Because a single line of shade from a tree branch can reduce the efficiency and power output of a solar panel by up to 50%.

You see, every solar panel is made up of solar cells. When one solar cell doesn’t get ample sunlight, it affects the energy production amount of the entire module.

Furthermore, the most common way to wire a solar system in Australia is in parallel (i.e. “string”) because it’s effective and cheap. The downside is that shade on one module affects the entire system.

So, before installing solar panels, make sure you get your installer to check for shading issues. If you don’t have one yet, we have a network of pre-vetted installers ready to step up to the plate. Whenever you’re ready, we’ll get you 3 FREE quotes from them right away.

Recommended: How shade affects solar panels

Age and maintenance

No matter the brand and model, all solar cells and modules have a degradation rate. For one, this means that solar panel efficiencies will decline over time. More importantly, this is what determines how long your solar panels last.

On average, modern solar panels have a degradation rate of 0.8% per year, leaving you with roughly 90% efficiency at year 20. On the contrary, this also means that your solar system will be at its most efficient on the day it’s installed and working.

High-quality panels have even slower degradation rates, giving you more solar energy for a longer time. SunPower’s Maxeon 3, for example, has a degradation rate of only 0.25%.

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Quality of the solar panels

Speaking of quality, high-efficiency solar panels are typically also some of the best-quality modules out there.

Canadian Solar’s HiHero, for instance, has an efficiency of 22.8%. As of today, it’s the most efficient solar panels Australia has to offer. It’s also among the most high-quality modules in the world, right up there with the likes of SunPower and REC.

Efficiency is just one thing to consider, though. You also have to think about the size of your solar system, the type of photovoltaic cell you need, and others – but that’s a topic for a different discussion.


How energy efficient are solar panels?

Most solar panels have an efficiency of 15-20%. High-quality modules are more efficient and can generate electricity better, though.

Are solar panels energy efficient?

Due to advances in technology, the efficiency of solar modules has vastly improved over the years.

When do solar panels start working?

Solar modules start working at around 6 AM, peak around noon, and stop working at around 6 PM. Note that these are only generalizations. The exact time also depends on the orientation of your solar system, the season, as well as the quality of your modules.


Circling back to the main question, solar panels work best at around noon in the summertime because that’s where solar irradiance is at its peak.

Now, does this mean it sucks at other times and seasons? Definitely not.

Depending on how your solar array is oriented, the range of its peak sun hours can also change. For example, east-facing arrays produce more solar energy during the day while west-facing ones get more direct sunlight during the afternoon.

Other factors such as the age, temperature coefficient, and quality of your modules affect your system’s efficiency, too.

Allow me to end this by pitching our service once more. When you’re ready to invest in renewable energy, our pre-vetted network of installers can get you 3 FREE quotes right away.