Tesla Powerwall 3 with 4.84KW Solar

Full Installation Walkthrough

This installation of a Tesla Powerwall 3 in the North East presented one of the most unusual engineering challenges we have encountered: a seventy-metre cable trench between the solar array location and the battery installation point. The property had a large agricultural outbuilding with an ideal south-facing roof for the solar panels, but the homeowner wanted the Powerwall 3 and all the associated electrical equipment installed in the main house, which sat some distance away across the property.

The system design featured the Tesla Powerwall 3, which is a significant evolution from the Powerwall 2. The PW3 incorporates a built-in solar inverter, eliminating the need for a separate standalone inverter and simplifying the installation architecture. However, in this case, the distance between the panels and the Powerwall created a unique challenge: how to efficiently transfer the DC solar generation across seventy metres of buried cable without excessive voltage drop or power loss.

Our engineering team carried out detailed voltage drop calculations to determine the correct cable specification for this distance. Standard solar DC cable would have resulted in unacceptable losses over seventy metres, so we specified a heavier-gauge cable that would keep the voltage drop within the permissible limits defined by the Powerwall 3 input specifications. The cable was rated for direct burial and UV exposure at the transition points where it emerged from the ground.

The trenching work was carried out by a specialist groundworks contractor working to our specification. The trench was excavated to a minimum depth of six hundred millimetres, with sand bedding below and above the cables and yellow warning tape laid above the sand backfill to alert anyone digging in the area in the future. The route of the trench was carefully planned to avoid existing underground services, tree roots and drainage runs, using CAT scanning equipment to verify the ground was clear before excavation began.

The solar array on the outbuilding roof consisted of panels configured to deliver the optimal DC voltage for the Powerwall 3 input, taking into account the additional voltage drop across the seventy-metre cable run. The panels were mounted on the south-facing roof slope using a heavy-duty mounting system appropriate for the exposed nature of the outbuilding, and all roof penetrations were sealed to agricultural building standards.

Inside the main house, the Tesla Powerwall 3 was mounted on the wall of the utility room, with the Tesla Gateway installed adjacent to the consumer unit. The gateway provides the backup switching capability and energy monitoring functionality, while the Powerwall 3 handles both the battery storage and the solar DC to AC conversion through its built-in inverter.

The seventy-metre cable trench was successfully completed and the DC cables were tested end-to-end before being connected to the Powerwall 3. The voltage and current measurements confirmed that our cable specification calculations were accurate, with the measured voltage drop falling within the projected range under full-load conditions.

Commissioning was carried out through the Tesla app following the standard Tesla Certified Installer protocol. The system was configured for self-consumption with backup reserve, and the grid failure simulation test confirmed that the Gateway seamlessly switched to backup mode with no perceptible interruption to the household supply.

This project demonstrates that creative engineering solutions can overcome challenging site conditions that might initially appear to make a solar and battery installation impractical. The seventy-metre cable trench added complexity and cost to the project, but the homeowner now has a Tesla Powerwall 3 system that provides excellent daily savings and whole-home backup capability, powered by a solar array that makes excellent use of the outbuilding roof that would otherwise serve no productive purpose.

The Tesla Powerwall 3 continues to impress us with every installation. Its built-in inverter significantly reduces the component count and wiring complexity compared to a Powerwall 2 installation with a separate string inverter, and the Tesla monitoring platform provides one of the best user experiences in the industry. If you have a property with an unconventional layout or challenging installation requirements, we encourage you to get in touch for a free assessment. At ALPS Electrical we thrive on solving technical challenges, and we will always find a way to deliver a first-class installation regardless of the site conditions.