Do solar panels work on cloudy days?
Harnessing the sun’s energy through rain and shine
Switching your fossil fuels out for solar is a great way to efficiently power your energy needs. Solar panels, also known as photovoltaic (PV) panels, harness the photons in sunlight through their solar cells and convert them into electricity. When determining if going solar is right for you, consider the price, type of panel and wattage — and choose a solar company with the right warranty.
It’s also important to understand the impact of environmental conditions on the solar panel system’s energy production. Factors that may affect a PV system’s energy production include time of day, season, weather conditions and the presence of shade or dust. To put your mind at ease when your weather is rainy, gray or cloudy, though, we’ve researched how overcast weather and indirect sunlight affect your energy supply.
Key insights
- Solar panels can generate electricity on cloudy days by absorbing reflected and weak light. While direct sunlight is optimal, it’s not required to keep your panels running.
- The power output of users’ solar panels decreases by about 20% based on the thickness of the clouds. Rainy weather may be beneficial for clearing the panel surfaces.
- Solar storage systems with batteries are best for generating energy at night and remaining off-grid
How well do solar panels work on cloudy days?
Capturing sunlight during cloudy days is more challenging but not impossible with solar technology. PV panels absorb both reflected and weak light — while direct sunlight is optimal, it’s not required. What's more important is your solar panels’ tilt angle and orientation. The array also needs to be free from obstructions and the right temperature.
» READ MORE: How do solar panels work?
According to the Environmental and Energy Study Institute, the solar panels’ power output may decrease by around 20%, depending on the thickness of the clouds.
Though this may seem like a large percentage, your solar system can still harness energy. Knowing the maximum voltage potential is helpful when determining the right number of panels and wattage for powering your home and other solar-powered items.
Based on the solar potential calculator provided by the National Renewable Energy Laboratory (NREL), even in cloudy Seattle, you can have an energy output of up to 6,621 kilowatt-hours (kWh) per year with an average-sized 6-kilowatt (kW) system. To put this in perspective, sunny Sacramento has an output of up to 8,782 kWh per year.
Do solar panels work on rainy days?
Rain itself isn’t detrimental to solar panels. In many cases, rain is beneficial to clear a panel’s surface of dust and debris. Don’t worry too much about rain damage; ground- and roof-mounted solar systems are built with this in mind.
When determining the best panel type, consider their characteristics. Monocrystalline is one of the most effective solar panel types for this type of weather. Bifacial systems are also useful because they are — like the name suggests — double-faced and highly reflective of other surfaces like sand or concrete.
Among the most durable solar system types, monocrystalline solar panels are one of the most efficient models, with high energy outputs. These systems are made of single silicon crystals and have the widest temperature range and life span, making them the perfect candidate for drawing sunlight even in rainy weather. The main downside is monocrystalline solar panels carry a hefty price tag.
Do solar panels work at night?
PV innovations have not entirely solved the sun-setting issue. At night, photons from the sun's rays are absorbed into the atmosphere, causing the solar panels to no longer conduct electricity.
The good news is breakthrough research supported by Stanford University in 2022 revealed that a thermoelectric generator works with solar cells to harvest the radiative heat flow of the earth. Essentially, the difference in temperature between the PV panels and the air reacts to create energy with this new technology.
Until these advancements are further proven and made into mass production, solar energy systems can either rely on the local power grid for power at night or function independently with an off-grid battery storage system. The latter option can save you from a local power outage. This stored electricity can take energy created during the day and use it during nighttime.
» LEARN: Solar energy pros and cons
How to store solar energy for later use
Solar storage systems, also known as solar-plus-storage systems, are proven to maintain a balance between the supply of electricity and the level of demand.
Warren Brown, the founder of Helius Hub, a solar energy company, shared some insights on optimizing energy production during cloudy weather and nighttime. According to Brown, oversizing the solar system with larger or more panels and using net metering can compensate for the lost energy. For going off-grid, solar batteries reduce reliance on utility service providers.
“Integrating energy storage systems, such as batteries, with solar panel installations allows excess energy produced during sunny periods to be stored for later use,” Brown said. “When clouds reduce solar panel output, stored energy can be utilized to power homes or businesses. This increases self-consumption and reduces dependence on the electrical grid.”
With solar-plus-storage, the energy output is controllable. The maximum megawatt-hour (MWh) depends on your battery size. You can either run your battery at full capacity for a shorter period of time, or smaller energy outputs for longer periods of time. This is helpful for overcast weather conditions, since users can gauge this supply and demand.
When clouds reduce solar panel output, stored energy can be utilized to power homes or businesses. This increases self-consumption and reduces dependence on the electrical grid.”
Going this route may be more costly upfront — solar batteries can cost upward of $7,000 — but this may prove to be more cost-effective than a monthly utility bill.
FAQ
Can solar panels generate electricity during a storm or heavy cloud cover?
Solar panels can generate electricity during bad weather. However, the cloud's thickness affects these energy levels. The electricity output will decrease due to the diffused sunlight, but that doesn’t mean PV systems can’t collect some energy.
What types of solar panels are most efficient on cloudy days?
Monocrystalline solar panels are an excellent option for cloudy weather, as they are highly efficient, meaning the panels have a high conversion rate of turning sunlight into usable energy.
How does the location and climate affect the efficiency of solar panels?
Since direct sunlight keeps PV systems running, the sunnier the region, the better. This means areas closer to the equator generally have a higher chance of harnessing electricity more efficiently.
To calculate the solar potential of your region, the NREL and other organizations offer solar potential calculators. Additionally, temperature plays a huge role in output — when temperatures increase or decrease too extremely, solar panels can immensely decrease production.
Can solar panels generate enough energy during the day to power my home at night?
If you have a solar battery storage system, yes, it is possible. The battery will store any excess energy generated during the day and use it at night or on cloudy days. Another alternative is connecting to your local power grid, but this will rack up a monthly utility bill.
Article sources
- U.S. Department of Energy, “ Solar Integration: Solar Energy and Storage Basics .” Accessed June 25, 2023.
- Environmental and Energy Study Institute, “ Solar Energy .” Accessed June 25, 2023.
- National Renewable Energy Laboratory, “ Solar Resource Data .” Accessed June 25, 2023.
- AIP Publishing, “ Nighttime electric power generation at a density of 50 mW/m2 via radiative cooling of a photovoltaic cell .” Accessed June 25, 2023.
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