19.1kW Solar with Tesla Powerwall — Part 3

Full Installation Walkthrough

The third and final part of this epic installation series brings together everything documented in parts one and two, culminating in the full commissioning, system testing and customer handover of the completed 19.1KW solar system with Tesla Powerwall at this impressive property in Seamer, near Stokesley.

With all the physical installation and wiring work completed in the previous phases, this final stage focused on the detailed commissioning and verification process that ensures every component is operating correctly, safely and at peak performance. Our lead electrician began the morning with a complete re-verification of all electrical test results, checking that nothing had changed since the initial testing was carried out at the end of phase two.

The SolarEdge monitoring platform was the first system to be fully commissioned. Each of the 44 power optimisers was verified as communicating with its respective inverter, and the panel layout was mapped in the monitoring software so that the homeowner would see an accurate graphical representation of their roof with real-time generation data for every individual panel. Both 6KW inverters were confirmed as operating within their normal parameters, with the firmware updated to the latest version available from SolarEdge.

The Tesla Powerwall commissioning was carried out through the Tesla app by our Tesla Certified installer. This process involves configuring the backup reserve percentage, which determines how much battery capacity is held in reserve exclusively for power outage protection rather than being used for daily self-consumption cycling. After discussing the options with the homeowner, we set the backup reserve at twenty percent, meaning 2.7kWh of the Powerwalls 13.5kWh capacity would always be available for emergency backup, while the remaining eighty percent would participate in the daily solar charge and evening discharge cycle.

The critical test for any backup-capable system is the grid failure simulation. We isolated the grid supply at the meter and observed the Tesla Gateway response. Within milliseconds, the Gateway detected the loss of grid power and seamlessly switched the entire property to battery backup. The lights did not flicker. The broadband router continued operating. The refrigerator compressor did not cycle. The transition was completely imperceptible, which is exactly the experience a homeowner should have from a properly installed Tesla Powerwall system.

We left the property running on battery backup for approximately thirty minutes while monitoring the system behaviour, checking that the Powerwall was correctly supplying all circuits and that the SolarEdge inverters had anti-islanded as required by G99 regulations. When we restored the grid connection, the Gateway smoothly transitioned back to grid-connected mode and the inverters resumed solar generation and battery charging within the prescribed reconnection delay period.

The generation meter was installed and verified, recording the initial reading that would be reported to the Smart Export Guarantee provider. We submitted the DNO commissioning notification to Northern Powergrid confirming the system specifications, the G99 approval reference number and the commissioning date. The MCS installation certificate was completed with all test results, equipment serial numbers and the calculated annual yield estimate.

The annual yield estimate for this 19.1KW system across three orientations is approximately 16,200kWh, which is a remarkable amount of generation for a residential property. Combined with the Tesla Powerwall providing 13.5kWh of usable storage, the homeowner will be able to self-consume the vast majority of their solar generation rather than exporting it to the grid at the much lower export tariff rate. Our financial modelling, based on the homeowners actual consumption data and their current electricity tariff, projected a payback period of approximately five to six years for the total system investment.

The customer handover for a system of this complexity was comprehensive and unhurried. We spent over an hour walking the homeowner through the SolarEdge monitoring app, the Tesla app, the backup functionality, seasonal optimisation strategies and maintenance recommendations. We explained how the system would behave differently in summer versus winter, how to adjust settings if they changed electricity tariff, and what the various alerts and notifications mean.

A complete handover pack was provided containing all MCS certificates, electrical test certificates, manufacturer warranty documents, equipment manuals, the G99 approval letter and our own ALPS Electrical workmanship guarantee. The homeowner now has a system that will generate clean, free electricity for twenty-five years or more, with the Tesla Powerwall providing both daily bill savings and the reassurance of seamless backup power during any grid outage.

This three-part project is one we are particularly proud of. It demonstrates the full breadth of our capabilities as both MCS-certified solar installers and Tesla Certified Powerwall installers, and it showcases the meticulous attention to detail that has earned ALPS Electrical over 250 five-star reviews and multiple industry awards.