Top 10 Solar Panel Efficiency Influences of Mother Nature

Your solar panel efficiency is dictated in large part by where your home is, both geographically and in respect to the sun's movements. Two solar systems of the exact same size and shape separated by only a few miles could produce startlingly different levels of energy. So the key is to optimize the orientation and location of your solar system for optimal solar panel efficiency. You need to consider orientation and mother nature when you set up your solar panels. One of these two factors is easy to cater to, and the other is a tough taskmaster. Let's look at them both.

The way you orient your collectors in relation to the sun is of obvious and vital importance. Yes, there are a lot of environmental and meteorological things to take into account, and we will handle those in a second, but there is one basic thing you can do to get started on the right foot. Solar panel efficiency is at the highest with south-facing orientations. As far as altitude goes, you get best year-round performance if you orient your panels to the sun's positions during the two most solar-oriented equinoxes, between the 2oth and 23rd of March and September. The angle you need depends also on your latitudinal position on the globe, but shooting for the sun on these days is a simple way of maxing out your production.

That takes care of orientation, but a smart solar design takes into account temperature, wind direction and speed, and rainfall, as well as a host of other weather conditions. Mother Nature has many aspects to consider. Let's take a look at the top 10 Mother Nature influences on your solar panel efficiency.

Sunlight – The South West U.S. gets far and away the most usable sunshine every day. The Northern United States and our border-buddy Canada get the least. In our Southern states, the days are longer because the sun is higher in the sky. But intensity matters as well. More solar power hits the earth easier, passing through less atmosphere, when the sun is directly overhead, thus increasing solar panel efficiency. And the summer sun is more powerful than the winter sun. Also consider the solar collector surface area that the sun will hit. The bigger the better.

Shade – Probably the single most devastating natural enemy of solar efficiency, shading can come in the form of tree and mountain cover. Remember that a solar panel with only 5% shading may lose as much as 50% of its output. Reduce shading as much as possible when locating your collector panels, and complement shaded panels with more panels in clear spots.

Snowfall – People do not generally consider snowfall in their solar panel efficiency equation, and that is a mistake. Snow can pile up on your panels, leading to partial or total blockage of the sun, and also creates a weight problem over time. You can also harness “hot spots” on your roof for maximum snow melting.

Cloud Cover – You still receive solar energy, but efficiency is reduced because the cloud acts like a filter, spread the sunlight out. Extremely cloudy places require much more thought before installing a solar power system.

Pollution and smog – Smog really means the accumulation of man-made pollution in the form of gas and smoke. This is a veritable blanket, dropping solar panel efficiency effectively to zero when it is heavy. They also decrease the full spectrum, filtering out much solar radiation that you desire.

Air thickness – Believe it or not, how dense your air is matters as well. In the mountains, the air is thinner, thus better solar production. Near the coast, or in areas of high humidity, the sun's rays have to swim through the air to get to you, and many get broken down and absorbed into the air, causing lessened solar panel efficiency.

Ambient temperature – Just remember this; the lower the outside temperature, the better the output. This might seem backwards to your way of thinking, but semiconductors don't work well when hot, and are more efficient when they are cool. A cold, clear day is better than hot and sunny every time.

Rainfall – Not only does the heavy air filter out sunlight, but rainfall and moist environs lend rust and corrosion a helping hand that you would rather avoid.

Heavy, frequent fog – If you have that typical misty, foggy morning every morning, angle your panels for noonday sun and aim towards the West. You allow for the longest possible daily solar absorption, and therefore max solar panel efficiency. Fog can also lead to rust and corrosion issues as well.

Wind – Wind is one of the most powerful natural forces, and can tear your panels to shreds. If you are in an area of heavy winds, mount on the failing side of the wind if possible, not in its face, and insist on heavy duty equipment. Most mounting variations list wind speed variables, so pay attention to them. Wind can cool surfaces quickly, so spending a lot of money on a solar water heater without taking the wind into account could devastate your output, and your solar panel efficiency. And adding blocking in the form of bushes and trees might just inexpensively do the trick.

Here are some great free and paid resources for information:


The National Renewable Energy Laboratory Here you can access many solar resources that help you figure the estimated BTUs per square meter per day that you can reasonably expect in your area. This is a nice one stop spot, because it takes into consideration the many factors Mother Nature throws at you so you can achieve maximum solar panel efficiency.

National Climatic Data Center - The NCDC offers solar charts that show you how much sun per day you can expect. They also show you how to create a sun chart specifically for your home.


Solar Pathfinder – charges $25 per week for the following service. They send you a solar sensor device that you employ on site. Aim this solar predictor south and level it with the attached bubble level. There is a chart you read under a protective dome that will show you when shade will be a problem, down to the day and month. They basically are programmed with all the weather and mother nature variables listed above, and provide data for solar panel efficiency.

There are versions which can be linked to your computer to offer dozens of extreme and complicated scenarios. If you ask a contractor for a free solar power estimate, it is likely he will show up with one of these, and you just might glean some free information about solar panel efficiency.

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