Electrical

Solar PV Installation Explained

Name: TradePlanr
Rating: 5 (100 reviews)
Author: TradePlanr

The panels are the easy part. A safe, compliant PV install is about DC isolation, correct inverter connection, and notifying the DNO.

Updated 21 Aug 202610 min read

A domestic solar PV system converts sunlight to DC in the array, an inverter turns it into AC, and it connects into the consumer unit to offset the home's demand. The electrical work spans DC and AC, each with its own isolation and protection rules.

This guide covers the electrical side of a PV install — string wiring, DC and AC isolation, the inverter connection, and the DNO notification every grid-connected system needs.

Key takeaways

PV systems have a DC side (array to inverter) and an AC side (inverter to consumer unit), each needing isolation.
DC isolation must be provided so the array can be worked on safely — the array is live whenever there is light.
The AC connection is a dedicated circuit into the consumer unit with its own protection.
Grid-connected systems are notified to the DNO under G98 (small) or applied for under G99 (larger).
The system is certified with an EIC and a PV commissioning certificate.

The DC side

Panels are wired into strings to build up the array voltage, which can be several hundred volts DC. The DC cabling runs to the inverter with a DC isolator so the array can be disconnected. Remember the array cannot be switched off — it produces voltage whenever there is daylight — so DC isolation and correct working practice matter.

Use the right connectors and DC-rated components, and keep the string voltage within the inverter's window across the temperature range.

The array is always live

There is no off switch on the panels — treat the DC side as live in any daylight and isolate before working on it.

The inverter and AC connection

The inverter converts DC to AC synchronised with the grid. Its AC output connects into the consumer unit on a dedicated circuit with appropriate overcurrent protection and, where required, RCD protection.

Position the inverter where it can be isolated and serviced, and label the isolation points clearly so anyone working on the installation knows there is a second source of supply.

DNO notification (G98/G99)

Grid-connected generation has to be registered with the Distribution Network Operator. Small domestic systems (up to 16 A per phase) are notified after installation under G98. Larger systems need a G99 application and approval before connection.

Skipping this step is a common compliance gap — the DNO needs to know about generation on their network.

Testing and certification

Commission the system by testing the AC circuit as normal, verifying the DC arrangement and isolation, and confirming the inverter's anti-islanding protection functions so it disconnects if the grid goes down.

Certify with an EIC for the AC circuit and a PV commissioning certificate for the system as a whole.

One commissioning record

TradePlanr's solar PV and battery commissioning certificate captures the system details and checks alongside the EIC, signed on site.

Frequently asked questions

Do I need to notify the DNO for solar panels?

Yes. Small domestic systems up to 16 A per phase are notified under G98 after installation; larger systems need a G99 application and approval before connecting.

Can you switch a solar array off?

Not the panels themselves — they generate voltage in any daylight. You isolate the DC side with the DC isolator and the AC side at the consumer unit, but always treat the array as live when there is light.

What certificate does a solar install need?

An EIC for the new AC circuit and a solar PV commissioning certificate for the system. MCS certification is also needed if the customer wants to claim export payments.

From guidance to action

Solar PV & battery certificateCommission and certify a PV system on site.Cable sizing calculatorSize the AC connection circuit for the inverter output.