The typical thought process regarding solar panels focuses on savings and sustainability. The money angle is important, but solar panels also call for critical changes to a home’s electrical safety setup. Grounding is essential, but many people assume that their house already has enough grounding to deal with solar panels. Additional grounding may be necessary based on your home’s electrical system, the installation type, and local codes.
What is Solar Panel Grounding?
There are two distinct grounding methods for an electrical system.
- System grounding gives the electricity in the system a safe path to follow. This helps when there’s too much voltage in the system, reducing the risk to appliances, devices, and even the wiring.
- Equipment grounding protects your investment in the metal frames, racks, and enclosures that come with a typical system. It also reduces the risks associated with rooftop lightning strikes and overloads.
Another issue is bonding. This ensures that two connected devices operate at the same electrical potential. Otherwise, a voltage difference between them can cause problems.
Why the Ground?
The Earth is large enough to have effectively an infinite capacity to absorb excess electricity. In the same way it survives gigawatts of voltage from a lightning strike, the soil also can absorb the excess current from your home’s electrical system.
Why Grounding Matters for Solar
A solar array is likely to have the highest direct current voltage of anything on your property. For residential systems, this can run from 300 to 600 volts. Commercial systems go even higher.
For some reference, a typical gas-engine car’s battery is 12 volts, and an EV’s battery is 48 volts. In other words, there is just a more dangerous current in a solar setup, and grounding makes it vastly safer by giving any excess somewhere to safely go.
Solar panels also usually sit on top of a roof. Adding more metal to a roof inherently makes it more vulnerable to lightning strikes. By definition, additional grounding helps by diverting that risk of excess voltage into the ground rather than through your house.
Relevant Electrical Codes
The National Electrical Code (NEC) is a set of guidelines widely adopted by localities. NEC 690 is the most relevant one for solar setups.
It requires:
- Grounding and bonding for all photovoltaic systems
- Rapid shutdown capabilities for safety
- Clear labeling for all grounding points
- Use of certified or UL-listed equipment
If you’re using a grid-connected solar system, your electric company may have additional requirements for attaching solar to your home. This is because of the risks of feedback into the main grid, especially during outages.
Necessary Grounding Components
The standard for grounding is a copper-clad steel rod eight feet in length and at least 5/8″ in diameter. Connecting to an underground metal pipe is also sufficient. Concrete encasements with metal lowered into the ground are also excellent.
A bare copper wire then has to connect other components to the ground. Wire size is specific to local codes.
A grounding electrode conductor connects the main bus to the ground, and bonding hardware ensures balanced voltage within the array. While not always required by code, you should strongly consider lightning arrestors or a built-in surge protection device (SPD). This is particularly true if your area gets a lot of lightning during storms.
Is Additional Grounding Necessary?
Many homes built since 1970 already have enough grounding to do the job, and our technicians can usually connect a solar array to these kinds of setups. We still need to verify that the existing grounding system is compliant for use with modern solar. In many cases, upgrades are necessary without a full rebuild of the grounding setup.
Age can also affect even a system with a compliant design. Grounding systems fail for many reasons, even odd ones like soil wetness changes or metal corrosion. Always have an electrician test the grounding system before connecting it to a solar array.
Ground-based arrays require a separate grounding setup. Large commercial systems do, too. Likewise, you should consider additional grounding if you reside in a high-lightning area. Adding battery storage to your system is another reason to consider additional grounding.
FAQ’s – Solar Panel Grounding
Does my home already have enough grounding for solar panels?
It depends. Many homes built after 1970 may have sufficient grounding, but an electrician still needs to verify that the existing system meets current code requirements for solar. Upgrades are often needed, even if a full rebuild isn’t.
What electrical code applies to solar grounding?
NEC 690 is the primary standard, covering requirements like grounding and bonding, rapid shutdown capabilities, proper labeling, and UL-listed equipment. Your local utility may have additional requirements if you’re connecting to the grid.
Do I need grounding if my panels are ground-mounted instead of roof-mounted?
Yes, ground-mounted arrays actually require their own dedicated grounding setup, separate from your home’s existing system.
What happens if my grounding system isn’t up to code?
An inadequate grounding system can expose your home to dangerous voltage spikes, lightning damage, and appliance or wiring failures. It can also create liability issues for insurance and complicate a future home sale.
Can I handle solar grounding myself?
No. Solar arrays carry voltages between 300 and 600 volts far beyond typical household wiring. This work requires a licensed electrician who can also document the installation properly for insurance and code compliance purposes.
Call a Professional
Working with a solar array is potentially lethal. Adding grounding to it isn’t a DIY project, even for someone comfortable with home electrical wiring work. You also want to be able to verify and document how the additional grounding system was connected, and a licensed electrician can do that with authority. This is important for insurance purposes. It also reassures potential future home buyers.
Ask for Mister Sparky
The team at Mister Sparky serves people who live in Gainesville, FL, and the surrounding areas. Our customers benefit from our decades of experience with a wide range of electrical systems.
Don’t put up with any malarkey, call Mister Sparky today to discuss the grounding needs for a solar system at your Gainesville home.
