Heavy rain can potentially damage solar panels, but the extent of the damage depends on several factors. In general, modern solar panels are designed to withstand normal amounts of rain without issue. However, extremely heavy rainfall over a sustained period can lead to problems. In this article, we’ll look at how rain can affect solar panels, what factors determine the risk of damage, and steps that can be taken to protect your system.
How does rain affect solar panels?
Rain itself does not damage solar panels directly. The issues arise when rain is accompanied by other conditions:
Accumulated debris
As rain falls on your roof, it can pick up leaves, dirt, pollen, and other debris. This material can accumulate on the surface of solar panels, blocking sunlight from reaching the cells.
Pooled water
During a heavy downpour, water runoff can pool on top of solar arrays instead of draining effectively. The weight of all this pooled water puts substantial pressure on the panels.
Hail
Strong storms sometimes produce hail, which causes dents and cracks when the balls of ice collide with solar panels at high speeds. The damage depends on the size of the hail.
Wind
Heavy rain is often accompanied by high winds. The combined force of wind and water can more easily dislodge panels or break equipment like mounting racks.
Dirt and erosion
The impact of raindrops on uncovered soil can loosen dirt and cause erosion around the installation site. This can gradually bury key components and block sunlight.
Lightning
Thunderstorms bring the risk of lightning strikes to solar arrays, which can damage sensitive electronics like inverters. Surges can also enter your home’s electrical system through the panels.
Factors that influence rain damage
Several key factors determine how much damage heavy rain and storms will cause to a solar panel system:
Rain intensity
Light showers are no big deal. But when rain starts falling at rates over 1 inch per hour, pooling and runoff become concerns. Fast, heavy rain also gives debris more momentum for impact damage.
Storm duration
Brief thunderstorms rarely cause major issues. But when heavy weather settles in for hours or days, problems compound. Sustained pounding takes a toll.
Wind speed
The faster the winds, the more force they pack. Gusts above 55 mph dramatically increase the odds of damage during wet weather.
Hail size
Small hail up to around 1 inch diameter will only cause minor chip damage. But balls 2 inches or more can smash through glass and dent aluminum frames.
Installation site
Rooftop solar panels see more debris and runoff versus ground mounts. Nearby trees increase the debris load. Good drainage reduces risks.
System age
Brand new solar panels in good condition can shake off rain impacts better than systems that are 10+ years old with weathering and wear.
Panel quality
Some solar panel manufacturers cut corners with low-grade materials prone to cracking, corrosion, and leaks. High-end products made by reputable brands hold up better.
Panel tilt angle
Steeper tilt angles cause rainwater and debris to run off panels more quickly, reducing pooling issues. Laid-back angles encourage puddling.
Facing direction
South-facing panels positioned perpendicular to prevailing winds suffer the brunt of blows during storms. East/west or sheltered alignments reduce wind impacts.
Maintenance
Keep debris cleaned off panels regularly so it doesn’t pile up. Also check for damage after big storms and make repairs. Well-maintained systems handle rain better.
Typical rain-related solar panel damage
Here are some of the most common problems heavy rainfall causes for solar installations:
Soiling and grime buildup
Dirt, leaves, pollen, bird droppings, and other gunk on your solar panels block sunlight. This can reduce energy output by up to 20% if the grime layer gets thick enough.
Broken glass
Hail hits or debris carried by high winds can fracture the tempered glass tops of solar panels. Cracked or shattered glass allows moisture inside.
Corroded framing
Wet conditions accelerate corrosion of aluminum parts like frames and racking equipment. This weakens the structure over time.
Warping
With enough sustained pressure from pooled water or accumulated soaked leaves, panel surfaces can start to warp or bow. This permanently alters their shape.
Detached panels
The combination of water weight and wind forces can pop panels out of their mounting clips, sending them sliding down the roof. This causes additional damage.
Internal moisture ingress
If water penetrates inside the panel through damaged seals or cracks, it can corrode interior components and junction boxes.
Inverter malfunction
Prolonged wet weather or lightning strikes can damage system electronics like inverters. This brings solar production to a halt until repairs are made.
Ground erosion
Water streaming off roofs or flooding can erode soil around posts and footings for ground-mounted arrays. This undermines structural stability.
Steps to protect solar panels from rain damage
While you can’t control the weather, there are things you can do to minimize rain-related solar damage:
Elevate panels off the roof
Increase the tilt angle and raise panels a few inches so water readily runs off and debris doesn’t press down directly.
Improve drainage
Use drip edge guards and gravel trenches to channel water away from the roof and site. Stop it from pooling.
Secure components
Reinforce mounting equipment and utilize robust wind deflectors so panels stay in place during storms.
Add protective canopies
Awnings or covers over the panels let water and debris shed before it even hits the equipment.
Fortify the site
For ground mounts, put down geotextile fabric beneath gravel to stabilize erodible soil and prevent sinking.
Clear debris frequently
Do rounds of inspection and manual cleaning after windy rainstorms so grime doesn’t accumulate.
Seal all penetrations
Use rubber gaskets and ample waterproof sealant anywhere components join or wires enter panels to block moisture ingress.
Install a lightning protection system
This provides a safe path to ground for lightning strikes to minimize electronics damage. Surge protection also guards against voltage spikes.
Swap old panels for newer models
If your array is 10+ years old, replacement with modern high-efficiency, weather-resistant panels can be worthwhile.
When to call for repairs
Don’t ignore signs of storm damage. Call for professional solar panel repairs or replacement if you notice any of the following:
– Visible cracking or holes in glass surfaces
– Missing, warped, or bowed panels
– Corroded or damaged frames, supports, or trackers
– Soiling covering more than 20% of panel surfaces
– Evidence of moisture intrusion inside panels
– Problems with inverter function after a storm
– Any other issues limiting system performance
Trying to patch things up yourself without proper training will likely void equipment warranties. The cost of repairs is usually far less than replacing the entire solar array.
Conclusion
Rain itself doesn’t harm solar panels, but extreme weather can cause problems. Heavy downpours, high winds, hail, and lightning bring the biggest risks for damage. Still, good installation practices and regular maintenance go a long way in helping systems withstand normal rainstorms. With prudent protection measures, you can keep your solar panels in tip-top condition and maximize power production for decades.