In mobile applications such as RVs, boats and other vehicles, the concept of "earth grounding" as understood in stationary installations (like homes or commercial buildings) is not applicable in the same way.
This difference is primarily due to the nature of mobile environments and their electrical systems.
Understanding the Purpose of Grounding in a mobile setting
Grounding solar panels helps to protect against electrical shock, ensure the proper operation of electrical components and reduce interference from electrical noise.
Chassis Grounding
In stationary installations, grounding typically involves a physical connection to the earth, which acts as a reference point for the electrical system and a safe path for fault currents. Mobile installations, however, are not physically connected to the earth, making traditional earth grounding unfeasible, therefore in many RV and motorhome setups, the vehicle’s chassis serves as the common grounding point, including for metal framed solar panels and mounts. This is typically done using a grounding wire that is securely attached to both the solar panel frame and a clean, bare metal part of the chassis.
Many mobile solar power systems are designed as "floating" systems, meaning that neither the positive nor the negative poles are connected to the frame of the vehicle or vessel (which would act as the ground in mobile applications). This design reduces the risk of electrical shock, as there is no path for current to flow to the ground (i.e. the chassis) in the event of a fault.
Isolation from Vehicle’s Electrical System
Mobile solar systems are often electrically isolated from the vehicle’s primary electrical system. This isolation helps prevent issues that could arise from connecting two systems with potentially different grounding or reference points.
Reduced Risk of Lightning Strikes
One of the key reasons for earth grounding in stationary systems is to protect against lightning strikes. While this risk is not entirely eliminated in mobile applications, it is significantly reduced due to the smaller size and mobile nature of these installations.
Use of Chassis as Ground
In many RVs and boats, the chassis or hull can serve as a ground for the vehicle's electrical system. However, this is different from earth grounding and is more about providing a common reference point for the vehicle’s electrical components.
Safety Considerations
Mobile solar systems are designed with safety features and protective devices like circuit breakers and fuses to manage fault conditions without the need for traditional earth grounding.
3. Use Proper Grounding Hardware
Use appropriate grounding hardware such as grounding lugs and suitable gauge copper wire to ensure a secure and reliable connection.
4. Avoid Ground Loops
Be cautious about creating ground loops – situations where multiple grounding paths can create a loop, potentially leading to electrical noise or interference.
The grounding should be done in a way that minimises this risk.
5. Consider the Entire System
Grounding the solar panels should be considered as part of the broader electrical system of the RV or motorhome, including the battery bank, inverter and any other electrical components. The grounding approach should be consistent across all these components, including metal component casings to be daisy-chained and/or grounded to a common point on the chassis wherever possible to reduce the electric potential between different positions (we want this to be as close as possible to zero). This video may help to explain the concept:
6. Electrical Codes and Standards
While RVs and motorhomes have some unique considerations, they should still comply with relevant electrical codes and standards. In many cases, this would be a combination of automotive and residential electrical standards.
7. Professional Installation
Given the complexities and potential risks, grounding should ideally be carried out or at least inspected by a professional electrician or technician who is familiar with RV or motorhome electrical systems.
8. Regular Inspection and Maintenance
Given that RVs and motorhomes are subject to movement and varying environmental conditions, regular inspections of the grounding connections and overall electrical system are important for maintaining safety.
Key Points:
- Ensure a solid connection to the vehicle’s chassis.
- Use appropriate materials and techniques for a secure grounding system.
- Integrate the grounding plan with the overall electrical system of the RV or motorhome.
- Consult professionals as needed to ensure safety and compliance.
Remember, safety is paramount when dealing with electrical systems, especially in environments like RVs and motorhomes where space is limited and the system is subject to movement and vibration.