How to Clean Solar Panels
Soiling on solar panels related to debris, dust, bird droppings, or dirt can get accumulated on the surface of the module and lead up to 30 % annual losses in worst cases.
Typical annual losses attributed to this factor are located between 2% and 5% regularly, however, by accumulating soiling on the PV system, losses can increase over time. That is why it is important to know how often or when to clean your solar panels.
The process to clean your solar panels can be as simple as using a soft brush with distilled water and dish soap. Here you will learn some valuable tips that will make the cleaning process even easier for you.
Tips Before Cleaning
Turn Off the PV System
The first step that you need to think of before cleaning your solar panels is to turn off the DC switch located in the combiner box. This is essential to guarantee your safety and to make sure that the solar panels won’t get damaged by water inside the junction box, exposed wires, or broken seals while DC electricity is flowing through the system.
New PV systems in the US according to NEC 2017 are now required to have a rapid shutdown system, that will instantly reduce the voltage of the PV array to zero from an easy access location inside the house or business. This will guarantee security in any case for the homeowners and firefighters as well.
Always remember to push that red button in the rapid shutdown box before going to clean your solar panels.
Use a Soft Brush Or a Sponge
When cleaning solar panels it is essential to use the right instruments. The glass is strong but using abrasive materials can scratch the surface of the glass, reducing its performance or even damaging the module.
If your solar panels are installed on the ground, then you can opt to use a simple sponge to clean them up or a soft brush as well. However, if they are located on the roof, then you must use a soft brush coupled with a long extension to make the work easier and safer from the ground.
Avoid Using Water with High Mineral Content
Module manufacturers recommend the use of distilled or de-ionized water to clean solar panels. Mineral-rich water may leave deposits of particles over time and its chemistry is not recommended for the glass of modules.
If you do not have access to de-ionized or distilled water, you can use a water-softening hose attachment to filter those minerals.
Do Not Use High Pressure
Using high pressure to clean the solar panels can force water to enter into the junction box or plugs that are not 100% sealed. As a general approach, it is recommended that when using a hose, pressure stays below 40bar.
It is also recommended that the water jet cleaning creates a sheet of water spray at the nozzle in order to reduce the pressure received by the glass.
Use Water with a Similar Temperature
Solar panel manufacturers do not recommend the use of cold or hot water to clean the panels. The reason behind this is that sudden and drastic differences in temperature could crack the surface of the glass.
It is best to clean your solar panels using ambient temperature water during early mornings (6-7 am), when the modules’ temperatures will be low after cooling down overnight and when the solar generation has not started.
Never Use an Abrasive Material to Clean the Solar Panels
Sometimes, homeowners or salespersons may advise you to use detergents to clean the modules. However, all that you truly need is the dish washing soap and water to clean them.
Using laundry detergents designed for other purposes is not recommended because they can create moisture or delamination at solar cell level which will void the warranty of the panels and will inevitably damage them.
Read Your Solar Panel Manufacturer Instructions
No one gives advice on how to properly clean and treat your solar panels like the manufacturer. Installation manuals of modules are generally available on the internet and many come included with your panels. Take a look at them and learn more about your modules.
Do Not Ever Walk over the Modules
Solar panels are designed to withstand specific distributed snow and wind loads. If your concentrated weight is above the designed loads then you could cause micro-cracking, declining the performance of the module over time. Besides, the solar panels’ surface can be slippery, and if you are adding soap and water to the mix, the probabilities of falling are quite high. As long as you are careful, the chances of solar panels being dangerous are low.
Source: JinkoSolar Installation Manual
The Simple Process
Gathering all of these tips let’s take a look at a review of the steps you need to follow:
- Get up early in the morning (6-7 am).
- Disconnect your PV array from the inverter by pushing the rapid shutdown button or pulling down the DC disconnect switch in your combiner box.
- Gather some distilled water and mix it with a little dish soap (just a little).
- Look for a soft brush and start cleaning your modules with the water mix.
- After all modules are soaped, remove the soap with a low-pressure hose.
- Leave the modules to dry over 30-45 minutes and turn back on the DC disconnect switch.
Other interesting solutions mainly designed for roof-mounted systems are the solar panel cleaning products like Polywater. They use specially designed chemicals for module cleaning that allow you to perform the maintenance from a safe distance on the ground or using stairs. Moreover, these products are designed with a specific water pressure that does not harm the surface of the glass. Polywater also uses a hose attachment bottle with the mix of water and soap with the option to rinse (using the mix) or to wash (only using water).
As you can see it is a simple process that, when carried out with a routine schedule, can maximize your solar energy outputs over the year.
Never forget that maintenance procedure is a two person job and that also involves checking your wires, possible signs of degradations, delamination, damages, or burns behind the solar panels (if possible).
Solar panel manufacturers never recommend to go up to the roof to clean your modules without special protection (harnesses), but with these tips, you can do it yourself while being on the ground or using movable stairs.