Installing an Alpha ESS SMILE home battery: what the job involves

Video reference. "Epic Solar PV Installation: How we installed Enphase Microinverters and the Alpha ESS Smile B3 +" is from Dore Woodman, a MCS-accredited UK solar and battery installer. The video walks through a complete solar and storage installation combining Enphase microinverters with the Alpha ESS SMILE B3-Plus, showing how the battery operates AC-coupled alongside the Enphase system and how the CT clamp is configured to manage import and export correctly.

1. Assessing the existing solar installation and consumer unit capacity

The first job on site is a load assessment. The installer measures peak import current on the main tails during a representative busy period, confirms the consumer unit has a spare way for the Alpha ESS circuit, and reviews any existing solar export capacity. If the home already has Enphase microinverters or another AC solar system, the Alpha ESS SMILE connects to the AC wiring rather than directly to the solar DC strings, making it what the industry calls an AC-coupled battery.

The installer also checks the earthing arrangement. Most UK homes use PME (TN-C-S) earthing. The Alpha ESS SMILE does not require a Type B RCD in the same way as an EV charger, so on a board that already provides full RCD protection a plain MCB is typically correct for the new battery circuit.

2. Choosing the installation location and preparing the wall

The Alpha ESS SMILE B3-Plus is a wall-mounted unit. A garage, utility room or plant area on an external or party wall is ideal: the wall must be solid enough to take the unit weight, the space must be dry and ventilated, and the temperature range must stay within the manufacturer's specified limits year-round. Direct sunlight on the unit can cause the battery management system to throttle charge and discharge rates to protect the cells.

The position is also chosen to minimise the AC cable run from the consumer unit and to keep the CT clamp cable routing tidy. A short cable run keeps installation costs down and reduces volt drop on the supply circuit.

3. Mounting the Alpha ESS SMILE unit

The installer fixes the wall bracket using the template from the Alpha ESS installation manual, verifies it is level in both planes, and hangs the unit. The SMILE B3-Plus is heavy enough to need two people for the lift. The cable entry glands at the base of the enclosure are used for the AC supply cable and the CT clamp signal cable. These glands must be correctly tightened to maintain the unit's ingress protection rating, which matters in damp environments such as a garage or outbuilding.

4. Running and connecting the AC supply cable

A dedicated cable runs from the consumer unit to the Alpha ESS SMILE terminal block. The conductor size depends on the unit's rated charge current and the length and routing of the cable: 4 mm two-core and earth covers most straightforward domestic installations, with 6 mm needed for longer runs or where derating applies. The cable must follow BS 7671 cable safe zones or run in mechanical protection throughout.

Inside the Alpha ESS terminal block, connections are torqued to the values in the installation manual. A loose terminal on a battery circuit is a thermal risk, so the installer checks every connection before closing the enclosure.

5. Fitting the MCB at the consumer unit

The supply cable is connected to an MCB in the consumer unit, sized to match the cable and the Alpha ESS unit's maximum charge current. If the board provides full RCD protection via RCBOs throughout, a standard MCB is usually all that is needed on the new circuit. If it is an older split-load board, the installer confirms the new circuit is on the RCD-protected side.

All MCB terminals are torqued before the board cover is replaced. The installer checks polarity and performs a continuity test on the new circuit before closing the board.

6. Installing the CT clamp and configuring energy management

A current transformer (CT) clamp fits around the grid import conductor inside the consumer unit or at the meter. The CT clamp signal cable routes back to the input port on the Alpha ESS unit. Correct orientation matters: if the clamp is fitted facing the wrong way, the Alpha ESS will read import as export and vice versa, causing it to charge from the grid instead of from surplus solar and discharge at the wrong time of day.

Once the CT clamp is in place, the installer configures the energy management mode in the Alpha ESS app. Time-of-use tariffs such as Octopus Go and Agile Octopus are supported, allowing the battery to charge during cheap overnight periods and discharge during peak-rate hours.

7. Commissioning on Alpha Cloud and notifying Part P and DNO

With all wiring complete and dead tests passed, the installer powers up the Alpha ESS SMILE and follows the commissioning wizard in the app, connecting the unit to the Alpha Cloud monitoring platform. A test charge and discharge cycle confirms the unit is reading household import and export correctly. The installer then notifies the installation through their Part P registered competent person scheme: you receive an Electrical Installation Certificate.

DNO notification follows the same rules as any other battery storage system. Units with a grid export capacity up to 3.68 kW on a single phase can be self-certified under G98, with the DNO notified within 28 days of installation. Larger units or those connected to a three-phase supply require G99 pre-approval from the DNO before installation begins. Keep both the EIC and the DNO notification letter with your property documents.

When to call us

Richard installs Alpha ESS SMILE batteries and other home energy storage systems across east Kent, handling DNO notification, Part P certification and commissioning on the same day. Get in touch for a free fixed quote.