Rooftop Solar Earthing in India: Requirements for Homes

Earthing is one of the most important safety parts of a rooftop solar PV system. A home solar installation adds exposed metal module frames, mounting structures, an inverter, AC and DC protection equipment, and sometimes a lightning-protection system. These parts must be correctly bonded and earthed so that faults and surges can be handled safely.

A safe rooftop solar installation needs correctly designed earthing and bonding for the PV array, AC equipment and lightning protection where required.

For Indian homes, key references include the Central Electricity Authority (Measures relating to Safety and Electric Supply) Regulations, 2023, IS 3043:2018 – Code of Practice for Earthing, and IS/IEC 62548:2023 – Photovoltaic (PV) Arrays: Design Requirements. The exact arrangement can also depend on your DISCOM, sanctioned single-line diagram (SLD), system design and local electrical requirements.

What Does Earthing Do in a Rooftop Solar System?

Earthing connects exposed conductive parts to an earthing system so that dangerous touch voltages can be controlled and protective devices can operate during a fault. Equipotential bonding connects conductive parts together so that unsafe potential differences do not develop between them. CEA’s safety framework specifically defines both earthing and equipotential bonding as electrical-safety concepts.

In rooftop solar, this is different from simply “putting a wire into the ground”. Good earthing requires correctly sized conductors, sound connections, suitable electrodes, electrical continuity across metalwork and measured performance after installation.

Earthing should also not be confused with lightning protection. A lightning-protection system handles lightning current through a designed air terminal, down conductor and earth termination. Surge protective devices (SPDs), meanwhile, help limit transient overvoltages and require an appropriate connection to the protective earthing arrangement. MNRE’s rooftop-solar quality-control draft treats earthing, lightning protection and surge protection as related but separate design areas.

What Earthing Is Normally Required?

A residential grid-connected rooftop solar installation commonly has three earthing functions:

Earthing function	What is typically connected
PV array/structure earthing	Module frames, mounting structure and exposed metal parts on the DC side
AC equipment earthing	Inverter body, ACDB and other exposed metal AC equipment
Lightning-protection earthing	Lightning air terminal/mast and its down conductor, where an external lightning-protection system is required

MNRE’s rooftop-solar draft manual requires electrical equipment, inverter, junction boxes and array structures to be properly grounded, while utility commissioning documents such as those used by BSES separately record AC, DC and lightning-arrester earthing.

SPDs on the DC and AC sides also need a correctly designed protective-earth connection. They do not automatically require a separate “fourth earth pit”; their connection should follow the approved design, applicable standards and manufacturer instructions.

A useful point for homeowners: “DC earthing” normally refers to protective earthing and bonding of exposed metal on the PV-array side. It does not mean that an installer should casually connect the solar DC positive or negative conductor to earth. Any intentional grounding of a current-carrying DC conductor must be compatible with the inverter, module design and applicable PV-array standard such as IS/IEC 62548:2023.

Do Indian Rooftop Solar Systems Need Three Separate Earth Pits?

Three earth pits are very common in Indian rooftop-solar specifications, but homeowners should not treat “three pits” as a universal rule that applies identically to every installation.

MNRE’s September 2022 final draft Quality Control Manual for small grid-connected rooftop solar PV systems specifies separate earth pits for DC-side earthing, AC-side earthing and lightning-arrester earthing. Importantly, this document is published by MNRE as a draft quality-control manual rather than being, by itself, a universal statutory specification for every home.

DISCOM requirements can be more specific. For example, BSES Delhi commissioning documents separately check AC earthing, DC earthing, lightning-arrester earthing and earth-pit details; BSES rooftop-solar technical specifications have also used AC, DC and LA earth pits.

Therefore, the right answer for your home is: follow the current DISCOM specification and approved SLD for your project. Requirements can differ by utility, system capacity and approved design.

What Earth Resistance Should Rooftop Solar Have?

A value of 5 ohms or less is commonly specified for Indian rooftop-solar projects. MNRE’s draft quality-control manual states that earth resistance should be as low as possible and should not exceed 5 ohms; it also describes around 1 ohm as a desirable electrode value. Some utility rooftop-solar specifications have similarly used a maximum total earth resistance of 5 ohms.

However, do not assume that “below 5 ohms” alone proves the installation is safe. IS 3043 addresses earthing as a complete system, while proper protection also depends on electrical continuity, bonding, conductor impedance and operation of protective devices.

Ask the installer to measure and record earth resistance during commissioning. Utility commissioning forms can require these actual test values.

What Size Should the Solar Earthing Conductor Be?

Conductor size depends on the protection design, material, installation method and whether lightning protection is present.

MNRE’s 2022 draft manual specifies a minimum 6 mm² copper or equivalent for earthing exposed PV-array metal frames where no lightning-protection system is installed, and 16 mm² copper or equivalent where a lightning-protection system is installed.

These figures are useful design references, not a do-it-yourself shopping list. A DISCOM specification or engineered design may prescribe a different conductor material or dimensions, including GI strips.

Can Solar Use the Existing House Earth Pit?

Possibly, but it should never be assumed to be suitable without inspection, design review and testing.

An existing household earthing system may have ageing or corroded connections, unknown electrode construction or inadequate performance. Some rooftop-solar specifications also call for dedicated electrodes for particular solar functions. The final arrangement must maintain proper protective earthing and equipotential bonding in accordance with the applicable design and standards.

The installer should assess the existing earthing system and show the final arrangement on the SLD or earthing layout.

What Should a Homeowner Check Before Commissioning?

Before accepting a rooftop solar installation, ask for:

• the approved SLD showing earthing and protection;
• earth-pit locations and identification;
• earthing-conductor material and size;
• bonding of every module frame and mounting-structure section;
• earthing of the inverter, ACDB and relevant metal enclosures;
• lightning-protection and SPD connections, where provided;
• measured earth-resistance values; and
• confirmation that earthing continuity tests were completed.

MNRE’s installation guidance specifically calls for electrical bonding of module frames and mounting structures and for continuity and earth-electrode resistance testing after installation.

Solar Earthing Is Professional Electrical Work

Solar modules can produce hazardous DC voltage while illuminated. MNRE’s installation guidance warns installers about dangerous DC voltage during module installation and specifies trained and qualified personnel for wiring work.

Do not disconnect PV cables, open DC boxes, alter lightning conductors or modify earthing yourself. Use a qualified solar installer and appropriately licensed electrical professionals.

Conclusion

For most Indian homes, rooftop solar earthing means proper bonding and protective earthing of the PV array structure, AC equipment and, where required, the lightning-protection system. Three dedicated earth pits are common in Indian rooftop-solar specifications, and 5 ohms or less is a common project acceptance target, but the final requirement must come from applicable standards, current DISCOM requirements and the approved system design.

Before your system is switched on, ask the installer for the earthing layout and actual test readings. Proper rooftop solar earthing is a fundamental part of electrical safety, not merely a commissioning formality.