How do temperature and shade affect solar panel efficiency?

Jun. 14, 2019
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Residential Commercial Solar Installation Solar 101

As spring turns into summer, temperatures are rising and trees are growing thick with green leaves. Warmer weather and shadier trees are welcomed by many here in Massachusetts; but they can also have solar PV system owners or homeowners considering going solar asking, “How will the heat and shade affect the efficiency of my solar panels?” Some even wonder, “Will my solar panels overheat?”


How Heat Affects Solar Panel Efficiency

Many of our customers in Massachusetts want to know exactly how changes in heat can affect solar panel performance. Solar panels are generally tested at about 77°F and are rated to perform at peak efficiency between 59°F and 95°F. However, solar panels may get as hot as 149°F during the summer. When the surface temperature of your solar panels gets this high, solar panel efficiency can decline somewhat.

That said, keep in mind that solar panels are made from highly durable materials that are designed to withstand extreme outdoor conditions — from freezing winter weather to intense summer heat. Moreover, the exact temperature of your solar panels will depend on factors like air temperature, geographic location, level of direct sunlight, and roofing material. An experienced solar contractor understands how to select and install solar panels to minimize any minimal effects of heat on solar panel efficiency.


Understanding temperature coefficient

If you really want to understand how much energy your solar panels may produce depending on the temperature outside, check the temperature coefficient on the manufacturer’s data sheet for your solar panels. The temperature coefficient tells you, in a percentage per degree Celsius, how much power a solar panel will lose when the temperature increases by 1 degree over 25°C (77°F).

For example, the temperature coefficient of LG NeON® 2 solar panels is -0.38% per one degree Celsius. This means that for every one degree Celsius above 25°C, the maximum efficiency of an LG NeON® 2 solar panel will decrease by 0.38%. Conversely, for every one degree Celsius below 25°C, the maximum efficiency of that solar panel will increase by 0.38%. (Yes — cooler, sunny weather is best for your solar panels and can help offset any decreased efficiency in the summer.)

So, if the outside temperature were 82°F (or 28°C) — the average daily high in Boston in July — and the surface of an LG NeON® 2 solar panel were roughly that same temperature, solar panel efficiency for that solar panel would decrease by just 1.14%.


How Shade Affects Solar Panel Efficiency

On a related note, many customers or future solar homeowners wonder how solar panels work in the shade. As a general rule, solar panels produce about half as much energy under clouds and shade as they do under direct sunlight. (So, yes, solar panels still produce energy in the shade.)

Shade may come from a number of sources, including trees, roof components like chimneys and dormers, or even other solar panels. (Keep in mind, however, that shade on a roof tends to change throughout the day as the sun travels through the sky.) Fortunately, a good solar contractor can help you assess your property before installing your solar panels to determine its solar potential — and how solar panels should be installed for maximum efficiency. Our Boston Solar team of engineers and designers will take all shading into account when designing your system for your home.


Maximize Your Solar Panel Efficiency with Boston Solar

If you’re considering having solar panels installed on your roof or property, get in touch with a local solar installer who understands how to choose the best solar panel panels for your home and install them in a way that maximizes efficiency.

At Boston Solar, we’re proud to be the number-one Massachusetts based residential solar installer, with over 3,800 solar installations and counting in places like the North Shore, the South Shore, and beyond. We have years of experience in designing and installing solar PV systems that maximize energy production, even when factors like heat and shading threaten to undermine solar panel efficiency.


Find out how much energy your solar PV system could produce in the summer. Call 617-858-1645 or contact us today to get a free quote!

How do temperature and shade affect solar panel efficiency?

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