There are several situations where you might need to disconnect solar panels, and it is essential to know how to do it properly. Disconnecting a solar panel is a manoeuvre that can be performed quite easily. To do this, it is necessary to wear safety gear, turn off the AC/DC disconnect switch, ensure the panels are not generating, verify voltage, and finally unplug MC4 connectors and mounting hardware.
Whether there is a storm coming, you are moving to another location, performing maintenance, replacing the modules, or for some other reason requiring you to disconnect and remove your solar panels, this article is for you. Here we will provide you with some safety precautions before disconnecting solar panels, detail every step of the disconnection process, and talk about the Rapid Shutdown requirement instated in the National Electric Code (NEC).
Safety Precautions: What Do You Need To Know Before Disconnecting Solar Panels?
When dealing with electrical components that might have live wires, it is crucial to be aware of and take every safety precaution possible. This section details some of the most important precautions that will help you be prepared to disconnect solar panels and avoid electrocution or fire hazard.
- Safety gear: Wearing safety gear is always important, especially when dealing with electrical components. We always recommend wearing insulating gloves, work boots, safety glasses, fire-rated clothes, and a hard hat.
- Pick the correct hour: When disconnecting solar panels, the hour you do it is essential. Solar panels cannot be just “shut off”, which is why we recommend disconnecting them early in the evening or before the sun rises in the morning.
- Disconnect the load: Finally, make sure there is no DC or AC load connected to the solar panels. To do this, make certain DC and AC circuit breakers are shut off before disconnecting the panels.
Step by Step To Disconnect Your Solar Panels: Complete Guide for a Safety Disconnection
Now that you know the most crucial safety precautions, we can dive into the steps you must follow when disconnecting solar panels.
- Turn Off DC and AC Disconnect Switch
As commented in the safety precautions, the first step when disconnecting solar panels is switching off circuit breakers. For most installations, you will need to turn off the AC disconnect switch from the inverter to the main electrical panel and then the DC disconnect switch from the PV array to the combiner box (if available) or inverter input.
- Cover the Solar Panel
Even though you should disconnect solar panels at hours when they are not generating power, you should always try to cover them with opaque cloths before removing them. Doing this will ensure no solar generation, making it safer to disconnect the modules.
- Measure the Voltage of Each String of Modules Before Disconnecting it
To avoid electrocution and fire hazards due to electrical arcing, use a multimeter or solar battery tester to measure the voltage at the solar panel or the array, ensuring they are close to 0V before disconnecting them. Since MC4 connectors used for solar panels are weatherproof, there will not be any naked conductors on sight, which is why you have to measure the voltage at the solar charge controller.
- Disconnect the MC4 Connector of Each Solar Panel
After everything is ready for disconnection, unplug the MC4 connector at the end of each solar panel. You can easily do this by using the disconnection/connection tool for MC4 connectors. If you lost it or did not have it at hand, you can always use a socket wrench to replace it.
- Cover the Plug of the Solar Panel With Electrical Tape
Whether you will transport your solar panel or leave it unplugged for a few days, cover the MC4 connectors with electrical tape to avoid electrocution risks.
- Dismount the Solar Panel by Removing Bolts, Screws, and Clamping Nuts
If this is not a portable solar panel and you need to move it, you should remove the bolts, screws, and clamping nuts at the mounting hardware used to fix the panel in place. After this, you can move the solar panel to their new location or replace the faulty ones with a new one.
How To Turn Off Your PV System During an Emergency? (Rapid Shutdown Disconnection Requirement)
To avoid fire and electrocution hazards, especially for first responders during a fire, the National Fire Protection Association (NFPA) included in the 2014 edition of the National Electric Code (NEC), the Rapid Shutdown (RSD) of PV Systems on Buildings article, better known as the 690.12 article. This article specifies the following:
- Installations with a conductor extended more than 10 ft. (outside) or 5 ft. (inside) from the PV array should have RSD systems.
- 10 seconds after activating the RSD system, conductors should be de-energized below 30 Volts and 240 Volt-Amperes.
- The aforementioned power and voltage should have those values when being measured between any two conductors or a conductor and the ground.
- RSD systems should be properly labeled under the 690.56 (B) article.
- RSD equipment should be listed and identified among the components of the PV system.
The aspect of the RSD system might vary slightly depending on the manufacturer. Some design the equipment with an ON/OFF switch, while others install a red button on it.
Disregarding the looks of the RSD system, this system should always be identified with the proper label (like the one in the figure below). This makes it easier for firefighters to locate the equipment, shut down the system, and attend the emergency.
Some photovoltaic (PV) homeowners do not know about RSD equipment, nor do they have this type of security system in place because their installation is small enough not to require it. While this is the case, installing this or a similar system for safety precautions is always advisable. In cases where there is a connection to the grid, this will be required.
Understanding safety precautions to avoid electrocution and fire hazards is vital when disconnecting solar panels. While these modules are designed to be safe, in the end, they are generating electric power and this could represent danger, which is why panels are usually only handled by certified solar panel installers.
With the information in this article, you can safely disconnect your solar panels to prepare for different extreme weather events or particularly to move your off-grid solar system. Always remember to take every precaution and ensure you only disconnect solar panels at the right time of day.
Understanding solar system safety precautions like the one shown in article 690.12 of the NEC, will also provide you with the tools to be more informed about PV system safety measures. This is something extremely important to know, especially in the case of fires or similar events. If you solar system is relatively large, connected to the grid or you are unsure on how to follow the steps, it is recommended that you reach out to a solar installer professional to do this for you.
Frequently Asked Questions (F.A.Q.)
The major factor affecting durability for solar panels is the temperature. While a person might not know how hot do solar panels get when left exposed under the sun and think that it will not get damaged since it is not connected to a load, this is a terrible mistake. Solar panels are always generating when exposed to the sun, the only difference is that when they are left without a load, they fall under open-circuit conditions.
PV modules left exposed to the sun under open-circuit conditions will run hotter than a solar panel connected to a load. This means that leaving solar panels disconnected and exposed, might not damage them right away, but it will reduce the solar panel lifespan faster than if they were covered or connected to a load, and it will also affect the solar panel efficiency in the long run.
Should I Disconnect Solar Panels When Performing Maintenance?
While shutting down a PV system is not required when performing a visual inspection, it is necessary when performing any type of maintenance, due to safety precautions. While it is necessary to shut down the system, it is entirely unnecessary to disconnect the solar panels from the array to perform maintenance.
All types of solar panels, the fuse box at each module, and MC4 connectors are manufactured with outdoor rating. This means that you can perform regular solar panel cleaning and maintenance by using solar panel cleaning tools, without having to unplug the panels, but you do have to disconnect the PV array from the system for safety measures.
Every time you will be adding new modules to the PV array, it is necessary to disconnect the modules from the system. When installing a new array, you only have to unplug two MC4 connectors (first and last) to add the second array in parallel. When adding a single or several modules to the array, you might only need to unplug one string and then add the other modules in series with the array.
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