Can Solar Panels be Turned Off?

We know that PV modules convert sun energy into electricity, but is there any way to turn off solar panels? What if you want to clean the panels or there is an emergency and you need to shut the system down? Is it possible?

Solar panels always generate electricity when exposed to light. But PV systems have a switch that can be turned off to stop current from flowing into appliances, and grid tied solar panels are automatically turned off during a power outage to protect utility workers.

How Do I Turn Off My Solar System?

As long as there is light striking the solar cells, it will convert sun energy into electrical power. However there are ways to stop the electricity from reaching appliances and devices.

The following methods apply to almost all types of residential solar systems. There are two basic setups, grid tied, where your PV system is connected to the power company, and off grid, where you depend on solar power only.

Shut Down a Solar System with PV Switches

Note: this is for grid tied systems only.

A PV switch stops the solar panel from directing power into the wiring system. The solar panels still generate voltage, but no energy will go into the wires, so it is as good as shut down.

To turn off the switch, follow these steps.

Step 1. Open the switchboard or meter box. Turn off the AC inverter main power.
Step 2. Shut down the AC breaker. If you have a battery it might have another AC breaker. Shut it off too.
Step 3. Shut off the DC breaker. This is often in the combiner box. If you have a battery bank installed, turn off its breaker as well.

Congratulations, you have turned off your solar system. Well yes, the panels can still produce energy, but none of it will get to your devices. Now you can perform troubleshooting, inspection or testing as long as necessary.

Turning off a solar panel is also necessary if you have to do some battery maintenance or other work. A system shutdown is also handy if you want to add more panels for instance.

To turn the solar system back on, repeat the steps above in reverse. Turn on the DC breaker followed by the AC breaker. Finally, turn on the AC inverter main power and your PV is back on.

The steps provided here are for a typical grid tied solar configuration. Yours might be different. Contact your solar installer if you are not sure how to turn off the system.

Automatic PV Shutdown Systems

In the United States, all grid tied solar systems are automatically turned off in case of a power outage. This is necessary to ensure the utility people are protected when they work on the power lines.

You are probably asking, if a solar panel only needs sunlight to generate power, why does my solar system stop working during a blackout?

The answer lies in how grid tied solar systems function. When sunlight hits the solar panel, it is converted into electricity. It goes into the inverter and is passed on to your lights, TV etc.

Any extra energy produced by the solar system is sent into the grid which you can access any time. If there is a power outage and your solar panels continue to supply electricity to the grid, it will pose a risk to line technicians who will fix the power.

If there is power coming from your system, it could electrocute the workers, so all grid tied inverters are turned off automatically when there is a power outage.

Battery backup systems. Because of this, many solar powered homes now have a battery bank as a backup power just in case. Solar batteries are like generators that can power essential appliances. How many batteries to get will depend on the number of appliances you want to run.

The shutdown mechanism only takes effect in case of emergency. If you want a simpler method of manually shutting down a solar system, there is an option explained below.

PV Rapid Shutdown Systems

Note: this is for grid tied systems only.

In many countries around the world, a rapid shutdown system is built into the solar system. Or in some cases you will be required to install one. Check the rules and regulations in your area to be sure.

As the name suggests, a rapid shutdown system is designed to quickly turn off a solar power system in case of emergency. By pressing a single button, the current supplied to the system is cut off.

This is a more convenient way to cut off solar power than manually shutting down the breakers one by one. It is also an effective safety mechanism in case of a system failure. While rapid shutdown systems are for grid tied panels, off grid PV configurations may have a similar feature depending on the design.

Solar panels are generally safe and reliable, but knowing how to quickly shut it off is still important. And in case your system does not have a rapid shutdown button, there are other ways to prevent solar energy from reaching your home wiring.

Solar Panel Covers

By putting a cover on the solar panel, you effectively shut it off. Remember, PV systems will keep generating power when exposed to the sun. By covering the panel with a black fabric or plastic sheet, it prevents the sun from reaching the cells.

This is a low cost but easy to “turn off” solar panels. You should always use the shutdown mechanism if yours has one. But if not, solar panel covers will do. Note there are some things to keep in mind when using these covers.

Use the right solar cover. Make sure the material is designed for PV panels. The cells generate heat and voltage, so the material must be capable of handling it.

Covers are for portable solar panels only. These covers are ideal if you have a solar powered boat or jeep, but for a rooftop solar array it is impractical. A cover not only cuts off the panel power source, but it also provides protection against dirt, dust and other contaminants. If your panels are ground mounted and small enough, covers can be useful.

Covers are not substitutes for PV shutdown systems. These should only be used for small panels and chargers.

Do I Need to Turn Off Solar Panels to Clean?

Most solar panels do not need cleaning. Usually rain is enough to remove the dirt. But going up the roof to remove bird droppings, foliage, grime and other debris once every six months is a good idea. So do you have to shut off the system?

Solar panels should be turned off before any cleaning is done for safety reasons. If you cannot shut if off because of a load, wait until sunset to commence proceeding. By this time the panel will have cooled down, making it safe to clean.

The cleaning solution must be designed specifically for solar panels to avoid damage. Our favorite is the Glass Gleam Solar as it simplifies cleaning and is easy to use.

Some might say these steps are really unnecessary. True, the power generated by each solar cell relative to its surface area is small. The chances of a fire or electrocution are very low on a properly installed PV module. But you can never be too careful when it comes to electricity and fire.

If it is summer, wait until sunset to clean the panels. Turn off the main AC power supply following the instructions given earlier before cleaning. Or you can just wait for the sun to set before going up the roof.

If you are not sure how to proceed, contact the solar installer. They probably have a cleaning service available. For RVs, it is easier to turn off the system and removing dirt from the panels.

Some pointers for cleaning solar panels:

• Wait until the temperature goes down. The panels will be hot to touch.
• Do not step on the solar panels. You will not get burned, but the panel may not be able to hold your weight.
• Do not clean the panels immediately after rain. The roof will be too wet. Wait for the roof to dry first.
• Use only the appropriate cleaning solutions to avoid damage.

What Happens If I Do Not Turn Off My Solar Panels?

If you don’t turn off the PV switch the panel will keep converting sunlight into electricity. It will only stop when the sun sets. All the energy produced will go into the battery bank, the grid or into the power load depending on your system setup.

A lot of people just leave their solar panel systems on. The only time it gets shut down is if there is a power outage. Unless you inspect the panels often, it is better to just leave it there as is. If you have a rapid shutdown system you can shut it down instantly.

Conclusion

Solar panels are among the safest power sources available today, and now you know why. Even though technically they cannot be prevented from producing electricity, there are several safety precautions built in.