Covering solar panels when not in use sounds straightforward - but at Accelerate Solar we need to flag the safety reality first: solar panels generate DC voltage whenever light hits them, even through a cover. A standard 400 W panel produces 30 - 45 volts open-circuit in daylight. That's enough to cause a serious shock or arc flash if you handle the system incorrectly. Any covering process must start with understanding this electrical risk, not just the physical protection aspect.
TL;DR: Use fully opaque, non-conductive covers, black polypropylene sheeting or purpose-made panel covers, to stop light from reaching the cells. That's the only reliable way to stop voltage generation. Never assume a covered panel is safe to touch without first isolating the system through the inverter's AC disconnect or rapid shutdown device. A standard 400 W panel can still produce 30 - 45 volts open-circuit under a partially translucent tarp in daylight. That's enough voltage to cause a serious arc or shock. Purpose-made covers cost $15 - $60 per panel and are designed specifically to block all light without trapping heat above 60 degrees C. Standard blue polyethylene tarps are not a safe substitute, they're translucent enough to let significant light through. If you're covering panels for roofing or construction work, activate rapid shutdown first, then cover. Don't skip either step.
Honestly, the cheap-tarp approach is responsible for more "I thought it was safe" injuries than the industry likes to admit. My take: spend the $30 on purpose-made covers and pull the disconnect first. Saving $20 is a bad trade if you brush a live DC string.
When Should You Temporarily Cover Solar Panels?
There are several legitimate reasons to temporarily take panels out of service. Understanding which scenario you're dealing with determines the right approach.
| Reason | Recommended Method | Duration |
|---|---|---|
| Roofing or construction work | Full opaque covers + rapid shutdown | Days to weeks |
| Storm preparation | Rapid shutdown only (tarps not recommended) | Hours |
| Extended vacation / system shutdown | Inverter AC disconnect | Weeks to months |
| Portable panel transport | Soft carry case | Transit only |
| Portable panel storage | Soft case, dry location | Weeks to months |
| Electrical work on home | Full system isolation by electrician | Hours to days |
The most common mistake: Homeowners sometimes cover panels with standard blue polyethylene tarps before roofing work. Blue tarps are partially translucent - they reduce light but don't stop it. A covered panel under a blue tarp on a bright day can still produce 10 - 20 volts at the panel terminals. If a roofer's metal tool contacts an exposed terminal, the result can be an arc or shock. Only fully opaque black covers, or proper rapid shutdown activation, reliably eliminate the electrical hazard.
What Are the Safest Ways to Cover Solar Panels?
Option 1: Purpose-made solar panel covers
The safest and most practical solution. These are sewn from UV-resistant, opaque polypropylene or polyester fabric that blocks all light. They typically clip or strap around the panel frame. Prices range from $15 - $60 per panel depending on size. Brands like Covertech and custom covers from solar installers provide fire-retardant and weatherproof variants.
Option 2: Activate rapid shutdown (RSD)
Since NEC 2017, all new US residential solar installations require a rapid shutdown system (NEC 2023, Article 690.12). When triggered, RSD drops string voltage to under 30 V within 30 seconds - safe for emergency responders and rooftop workers. Many modern systems (SolarEdge, Enphase) have RSD built in. This is the safest approach for roofing work because it doesn't require physical covering at all.
Key Takeaway - NEC 2023 Article 690.12 requires all new residential solar installations in the US to include rapid shutdown capability that reduces conductor voltage to 30 V or less within 30 seconds of initiation. This standard, first introduced in NEC 2017 and tightened in subsequent code cycles, means that any solar system installed after 2017 should have a rapid shutdown button or switch accessible to first responders and homeowners. If your system predates 2017 or lacks RSD, physical opaque covers combined with DC isolator disconnect are your safest alternative for rooftop work.
Option 3: Switch off the inverter's AC and DC isolators
For non-emergency shutdowns (extended absence, maintenance), switching off both the AC isolator (at the switchboard) and the DC isolator (at the inverter) stops the system from exporting power and disconnects the inverter. This does not eliminate panel-level voltage - panels still generate DC at the string level between the panels and the now-disconnected inverter. Physical covering is still needed if anyone is working near the panel terminals.
Option 4: Soft cases for portable panels
Portable 100 - 400 W folding panels (common in off-grid camping and van setups) should be stored in fabric carry cases when not in use. Close all Velcro or zipper closures to fully block ambient light. Disconnect any attached charge controllers or batteries before storing.
What Should You NOT Use to Cover Solar Panels?
Why do well-meaning DIY covers cause so many problems? Because most household materials either trap heat, scratch glass, or quietly let light through.
What to avoid: Standard hardware store tarps (blue polyethylene) are the most commonly misused covering material. They're partially translucent, they trap heat that can degrade panel encapsulants at high temperatures, and they're not UV-stabilized for long-term outdoor use. Heavy tarps can also physically scratch anti-reflection coatings on panel glass if they move in wind.
Never use:
- Clear or translucent plastic sheeting (still passes light, still generates voltage)
- Cardboard (gets wet, disintegrates, doesn't block enough light reliably)
- Plywood directly on panels (can crack glass under weight or thermal expansion)
- Standard poly tarps for anything longer than a few hours (heat buildup risk)
- Aluminum foil or metallic covers (conductive - creates short-circuit risk if it contacts terminals)
What About Covering Panels Before a Storm?
This is a common question, and the advice from solar panel manufacturers and NREL is consistent: don't cover panels before a hurricane or high-wind event. Here's why:
Any tarp or cover becomes a sail in high winds. The lift forces can crack glass, damage frames, and pull mounting hardware off the roof - damage that the uncovered panel would have survived. Certified solar panels (IEC 61215) are tested for hail up to 25 mm at 23 m/s, wind pressures of 2,400 Pa (equivalent to roughly 150 mph), and snow loads of 5,400 Pa. Your panels are almost certainly more storm-resistant than any improvised covering.
The better pre-storm checklist: confirm your inverter's rapid shutdown is functional, ensure panel mounting hardware is secure, document your system with photos for insurance purposes, and - if flooding is a risk - turn off the main electrical supply at the breaker panel. OSHA's electrical safety guidelines recommend treating all solar conductors as energized until verified de-energized by a qualified person.
For long-term system health and to catch any degradation from storm debris or aging sooner, panel-level monitoring via the SolarEdge P370 power optimizer gives you per-panel output data that flags damage within days.
Key Takeaway - IEC 61215-certified solar panels are engineered to withstand 25 mm hailstones at 23 m/s impact velocity, wind pressures of 2,400 Pa (roughly equivalent to 150 mph sustained winds), and snow loads of 5,400 Pa. These ratings exceed the structural survival thresholds for most residential roofing materials. Covering panels with tarps before a hurricane adds wind-catch area that can rip mounting hardware from the roof - causing damage that the uncovered panels would have survived. The only pre-storm action that improves safety is activating rapid shutdown and securing loose objects around the array.
What Happens If You Leave Solar Panels Uncovered During Storage?
If you're decommissioning panels for a season - during a renovation, a prolonged absence, or while storing portable panels between trips - leaving them uncovered and exposed creates several risks that accumulate over time.
Dust and debris accumulation: Even a few weeks of uncovered outdoor exposure allows dust, pollen, bird droppings, and leaf litter to build up on the glass surface. Studies by NREL show that soiling losses can reach 5 - 25% of output depending on tilt angle and local conditions. Panels stored flat (0 degrees tilt) accumulate debris fastest because rain can't naturally wash the surface.
Micro-crack risk from thermal cycling: Panels left exposed to full sun while disconnected still undergo daily thermal cycling - heating to 60 - 75 degrees Celsius during the day and cooling to ambient temperature overnight. Over months of cycling without any energy being drawn from the cells, the cumulative thermal stress contributes to micro-crack propagation in the silicon wafers. NEC 2023 Article 690 doesn't require covering stored panels, but manufacturers recommend it as a best practice for long-term storage exceeding 30 days.
Warranty implications: Most tier-1 manufacturer warranties (LONGi, Trina Solar, JA Solar) require panels to be installed according to manufacturer instructions within 6 - 12 months of purchase. Panels stored outdoors without covers for extended periods may have warranty claims challenged on the grounds of improper storage. Keep purchase receipts and document storage conditions with dated photographs.
UV degradation of exposed backsheets: The polymer backsheet on the rear of the panel is designed to resist UV exposure from below (reflected ground light), but panels stored face-down or at angles that expose the backsheet to direct overhead sun can experience accelerated backsheet degradation. Store panels vertically in racks or face-up with opaque covers to protect both sides.
For a deeper look at how these aging mechanisms compound over a panel's lifetime, see our guide on old solar panels.
| Covering Method | Pros | Cons | Cost per Panel |
|---|---|---|---|
| Purpose-made panel covers | UV-resistant, fitted, breathable, fire-retardant options available | Must match panel dimensions; limited availability for uncommon sizes | $15 - $60 |
| Rigid polycarbonate sheets | Excellent impact protection, fully opaque, reusable | Heavy, requires mounting hardware, risk of scratching glass if improperly placed | $30 - $80 |
| Panel blankets (padded fabric) | Best for transport and storage, cushioned protection against impact | Not weatherproof for outdoor use, must be stored dry | $25 - $70 |
| Black polypropylene tarp | Inexpensive, fully opaque, widely available | Not breathable - traps moisture; degrades in UV after 6 - 12 months | $5 - $15 |
How Do You Maintain Covered Panels for Long-Term Protection?
When panels will be covered for weeks or months, regular inspection prevents small problems from becoming permanent damage. Check covered panels at least once per month - more often in hot or humid climates.
Moisture is the primary enemy of covered panels. Condensation forms when temperature drops overnight cause humid air trapped under the cover to reach dew point. Over time, persistent moisture can corrode junction box connections, degrade the adhesive bond between glass and encapsulant, and promote mold growth on frame surfaces. Leave a 2 - 3 cm ventilation gap at the bottom edge of the cover to allow airflow while still blocking light.
For systems that will be down for extended maintenance, consider how panel-level monitoring helps when you bring the system back online. The SolarEdge P370 power optimizer provides per-panel performance data from the moment of restart, letting you immediately identify any panels that suffered degradation during the shutdown period. For tips on maximizing output after bringing your system back, see our guide on increasing solar PV yield. And if you're curious whether panels still produce anything after dark without covers, our guide on whether solar panels work at night explains the science behind zero-light output and battery storage alternatives.
Summary
Covering solar panels safely requires understanding that panels remain electrically live whenever light - even diffuse indoor light - reaches them. Fully opaque, purpose-made covers ($15 - $60 per panel) are the most reliable physical covering solution, while activating your system's rapid shutdown eliminates panel-level voltage without physical covering at all. For storm events, leave panels uncovered - they're engineered to survive extreme weather and improvised tarps create more risk than they prevent. For portable or off-grid panels, purpose-made soft storage cases are the right solution. For more ways to protect and optimize your solar investment, see our full guide on increasing solar PV yield by 20%. For ongoing cleaning schedules, inspection checklists, and monitoring recommendations, see our solar panel maintenance guide.