Solar panels have taken the world by storm over the last decade, and their popularity does not seem to be slowing down anytime soon. The number of solar installations crossed 2 million in 2019 and is expected to be double that by 2023.
Although these systems are not new, many people still have not figured out how exactly the technology works. How do solar panels produce electricity? Do solar panels work in cloudy weather? What about after dark — do solar panels work at night?
We answer these questions and more below. Let us take a look!
Do solar panels work in cloudy weather?
Solar panels do work on cloudy days — but not as effectively as they would on a sunny day. Expect them to produce 10-25% of their normal power output, depending on how thick the cloud cover is. But there is an interesting twist: although they work better on sunny versus cloudy days, solar panels do not work best in particularly hot climates. In fact, solar panel output begins to fall if the temperature rises above 77 degrees Fahrenheit (25 degrees Celsius).
Because of this, solar panels work better in certain areas than others. For example, even though Las Vegas has sunnier and hotter days, solar panels tend to generate more power than in San Francisco. SF’s cooler weather keeps the device at an optimum temperature for energy output when the sun is shining.
You might also be surprised to know that solar systems are popular in many famously overcast places, such as in the city with the cloudiest days in America, Seattle. The second cloudiest city, Portland, Oregon actually ranks among the top cities for solar power in the US. Both cities benefit from long summer days with mild temperatures — ideal conditions for maximum solar production — which helps balance out lower production in the cloudy winter months. In summary: on cloudy days solar panels do work; just less effectively. But solar panel performance also drops when it is too hot. Solar panels can work and be worth it across a range of different climates.
Do solar panels work at night?
The answer is no, they do not. As we mentioned earlier, solar panels need light — preferably sunlight — to create energy. Although they can generate some energy from other light sources such as streetlights and even the moon, the output is very low. Because of this, solar panels go into sleep mode at night, i.e. they become inactive and stop producing electricity.
Then how do homes with solar panels have power at night?
As mentioned above, solar panels produce no electricity at night. But they tend to produce extra power during the day when the sun is out. In order to balance things out, and keep the electricity running after dark, solar customers use either solar battery banks to store energy or net metering.
Solar battery storage
The concept behind solar energy storage is simple. Most solar systems are intentionally designed to produce more power than your home needs during the daytime. The surplus power generated during the day is stored in a solar battery solution.
At night, when your solar panels are in sleep mode, you can use the stored energy held by the battery system to power your home. Some houses with his setup are even able to operate off grid, i.e. completely independent of the utility.
Net metering – which is like using the grid for storage
If your solar panel system does not have storage, you can still use your surplus solar energy at night. How? Through net metering! With net metering, you do not have physical energy storage at your home. Instead, the excess power your solar panels produce during the day is exported to the utility grid. You receive credits for this power, which accumulate in your account.
Later, at night — or any other time you use power from the grid — you can use your credits to offset the cost of the energy. In other words, net metering lets you store the economic value of the excess power you produce, which you can use to reduce or even completely cancel out your electric bills. Net metering makes solar power a very good deal.
Read more: How Does Solar Power Work?
Written by: Laila El Azhary