When you first get solar panels for your home or camping, it might be a concern for you if the panels might be damaged by water and if they really are waterproof as claimed.
Solar panels are waterproof because they are constructed of a top tempered glass sheet in a metal frame with a backsheet of 2 layers of a polymer-based material, all sealed with a specialized sealant glue.
Glass for waterproofing in solar panels
The most important element that makes a solar panel waterproof is the glass used for the front panel. Glass is the perfect material for a solar panel as the waterproofing material needs to be transmissible to let the sunlight reach the sunlight photovoltaic cells of the panel.
Solar panels will literally be facing the elements for the good part of 30 years. The glass used in the construction should withstand the sun, wind, snow, and even hail.
Solar panel glass is the most important barrier which protects solar photovoltaic cells against damaging external factors, such as water, vapor, and dirt.
Different types of glass used for solar panels
There are basically two different types of glass used for the construction of solar panels:
| Thin film solar panel | Crystalline solar panel | |
| Glass used | Standard | Tempered |
| Thickness | 2.5mm | 3mm to 4mm |
| Glass surface | Smooth | Rough |
| Antireflex coat (AR) | No | Yes |
Thin-film solar panels with smooth glass
These panels are normally cheaper, and their build quality is not of the same standard as the more durable crystalline panels.
Thin-film solar panels use standard glass, which is about 2.5mm thick. This standard glass has a smooth surface which can often lead to delamination, which means that the EVA film does not bond well with the glass, and over time it comes loose from the glass.
This means that these panels will lose efficiency over time and will have to be replaced much sooner than crystalline panels.
Crystalline solar panels with tempered glass
Crystalline solar panels normally use glass that is 3.2mm thick. The glass has a rough surface for the EVA to bond properly to it. A smooth surface on the glass will lead to de-lamination.
Before the glass is tempered, one layer of anti-reflective (AR) coating is applied to the glass to reduce the amount of reflective light from the solar panel.
Tempered glass also has some additional properties that make it suitable for use in solar panels:
- It is up to four times stronger than standard glass, making it impact-resistant and hail-proof.
- It is considered safe when it breaks, and it will shatter into small pieces that will reduce the likelihood of causing injury.
One downside of tempered glass is that it is much heavier than normal plate glass, and because of this, a standard 250W solar panel will weigh about 20kg.
Polymer backsheet for waterproofing
The final bottom layer of a solar panel is the backsheet that will also add to the waterproofing of the panel. The backsheet consists out of single or multiple layers of polymer material.
The backsheet of a solar panel has the following functions:
- Protect against water and vapor.
- Protect against dirt and dust.
- Protect against ultra-violet radiation.
- Be scratch-resistant, especially during installation.
- Be able to provide these functions during a wide range of temperatures: -40 degrees to +80 degrees.
The best solar panel back sheets are constructed from Tedlar® PVF film, which has properties that makes it the industry leader in this market,
Tedlar offers two types of backsheets:
Tedlar® TPT Backsheet
- It offers the best protection from UV, thermal, moisture, mechanical, and chemical stress in harsh climates.
- The inner Tedlar® PVF film is more stable under heat and UV exposure than single-sided tie layers.
Tedlar® TPE Backsheet
- The critical outer layer features Tedlar® PVF film that has protected solar modules for more than 30 years.
- It offers the best balance of properties in single-sided back sheets for general-purpose applications.
What happens when a solar panel get wet?
Water or moisture will cause no damage to a solar panel as it is totally waterproof with its top glass sheet and polymer backsheet.
The overcast conditions that come with rain will affect the solar panel’s performance and reduce its energy production by 50% or more.
Solar panels are also designed to be installed at an angle because water and even snow will easily slide off the panel.
Can a solar panel be submerged in water?
As a general rule, the careful construction of solar panels makes them very waterproof, and they can withstand a heavy amount of rain and water. Still, it might not be good to intentionally submerge a solar panel as they are not designed for it.
Submerging the panel for a long time might cause the metal frame to start corroding, and some of the electrical connections might also be damaged when being submerged for a long period of time.
How can solar panels be protected from water?
When solar panels are installed on the roof of your house, there is nothing really that you can do to protect the panels from water, and there is really no need to, as the panels are designed to be waterproof and weather-resistant for many years.
When you have solar panels on a separate installation where water might damage the structure or foundation of the structure, retaining walls might be a solution to protect the panels from the water.
Retaining walls can re-direct or stop the flow of water in case of heavy rain or floods.
Solar panel warranty against water damage
Most solar panels that reputable companies manufacture will have a performance guarantee as well as an equipment guarantee.
If your solar panel is damaged by water, it will be covered by the equipment guarantee.
The equipment guarantee on solar panels is normally from 10 to 12 years, depending on the manufacturer.
