How hot do solar panels get and how does it affect my system?

How hot do solar panels get and how does it affect my system?

A concern many homeowners have is that their solar system will overheat. In this article, we will discuss how temperature affects solar panel efficiency.

Can solar panels get too hot?

In theory, yes. However, it is extremely unlikely, as solar panels are made to withstand extreme temperature and weather. Solar panel manufacturers are well aware that their products are going to get hot, and any malfunctions from temperature wouldn’t look good on them. While hot solar cells produce less, they will still produce the majority of their rated power.

Are solar panels hot to the touch?

Generally speaking, solar panels are 20°C (36℉) warmer than the ambient temperature. For example, the ambient temperature in the desert can reach 113℉, which this means solar panels in this climate can reach 149℉. While this would be uncomfortable to touch it is unlikely to give you any serious burns. A more valid concern is touching the metal frame of the panel.

What is the optimum temperature for solar panels?

Put simply, as cold as possible. All electrical equipment is at its maximum efficiency when operated cold. That is why when obtaining the rated maximum output of most solar panels, testing takes place at a relatively chilly 5°C (41℉), with 1,000 watts per square meter of light being shone at them.

While these conditions are a little unrealistic—1000 watts is way more sunlight than you should expect to hit solar panels—it's reassuring to know that your solar panels can cope with that much power output.

What is the maximum temperature a solar panel can operate in?

Most solar panels have a rated “solar panel max temperature” of around 185℉. While the amount of power produced by the panel decreases it is highly unlikely that any major malfunctions will occur as a result of temperature.

What is a temperature coefficient?

A temperature coefficient is the percentage decrease in energy production for each degree Celsius over 25℃ (77℉). Solar power, like all electronics, produce less energy the hotter it is. The temperature coefficient of some major panel manufacturers is below.

Using the formula in the table above we can work out that a panel with a temperature of 45℃ (113℉) will have a 5.8% reduction in its energy output assuming the SunPower model is used.

What is solar panel efficiency?

Solar module (panel) efficiency is the percentage of light that strikes the surface of the photovoltaic cell and is converted into energy. The photovoltaic cell is in the shape of a square and makes up the panel. Rooftop solar panels can be made of anywhere from 60-96 solar cells. Most reputable solar cells will have an efficiency between 15% and 22%.

What is the highest efficiency panel available?

SunPower's SPR-X21-350-BLK listed above is the highest efficiency residential solar module. The SPR-21-350-BLK also has the second best temperature coefficient at an impressive -0.29%/℃.

Is it worth paying extra for a premium brand panel?

Despite the extra price tag premium panels lose less output as temperature rises, have a higher efficiency and come with stronger warranties. The industry has implemented 3 different tiers for judging solar manufacturers: Tier 1, Tier 2 and Tier 3. Tier 1 represents the highest quality. Some examples of Tier 1 brands include Sunpower, Solarworld, Panasonic, LG, Trina, Jinko, Rene Solar and Canadian Solar.

Generally speaking, Tier 1 panels cost about 10-30 percent more than Tier 2 or 3 panels. Reputable installers typically use Tier 1 brands, and panel prices work out to be very similar. That being said, you’ll probably have to pay extra is for the very top Tier 1 brands like Panasonic or SunPower.

Brands like Panasonic and SunPower have power outputs that degrade much less over time than other panels. This means more energy will be produced over the life of the system, which is less power that needs to be purchased from the utility. Despite the additional $1,000-$3,000 to your initial investment, the savings over time will more than makeup for this.  

How long is a solar panel warranty?

There are two types of warranties for solar panels: product warranties and power output warranties. Product warranties cover defects in the panel that cause it to stop working and normally last for 10 years. The power output warranties are a guarantee that the panel will produce a certain percentage of its rated output, usually for a term of 25 years.

A good example is to compare the warranties of Panasonic and SunPower, two major Tier 1 brands.

You can’t really go wrong with either brand of panel. Both Panasonic and SunPower offer a product warranty 15 years greater than the industry standard. They also guarantee that in the 25th year of use the panels will still be outputting over 90% of their rated output.

Remember, it is very likely that your panels will actually produce even more than the warranty baseline. Both SunPower and Panasonic give themselves a little leeway so they aren’t hit with having to pay out lots of warranties.

How likely is a solar company to honor their warranty?

Depends on the strength of the manufacturer. This is another reason why you should go for Tier 1 panels: the larger, more established companies are far less likely to go bankrupt and not be able to honor their warranty. A strong suit to LG and Panasonic panels is that these companies are so large, and manufacture so many different products, that they’re very likely to be around for the 25-year term of your solar warranty.