The project involved a 200-foot trench at the back of the house, as well as a 45-foot utility-grade trench into the street. It also required the relocation of the gas service. The most important aspect of the project was upgrading the main electrical service at the property from 200 AMPS up to 320AMPS. Through extensive preconstruction planning meetings, we planned and managed all tasks with all parties, including the city inspectors and the gas utility providers.
The installation of the premium SunPower 415-watt AC modules with G-Series Factory Integrated microinverters took just one day. It took five business days for the extensive trenching to be completed. Two days of preparation work were required for the electrical work. The third day was spent on primary work. During this time, the electrical team conducted a controlled outage with utility to upgrade the property’s service to 320 amps.
This project had 10 inspections across three permits. Each inspection was passed the first time. The homeowner reported a net credit electric bill after he had installed the system. This despite the fact that the home has three air conditioners and an all-electric SUV, as well as a climate-controlled 1,900-square foot garage.
Two 13.5 kWh Tesla Powerwall2 batteries were installed in the garage. Two Tesla Powerwalls provide backup power for all house loads in case of an outage. In case the homeowner wishes to add more backup battery, we also increased the size of the underground conduit connecting the Tesla Powerwalls circuits to the main electrical panel.
From the main electrical service in the house, we used 200 feet to trench the area. We did this at a depth 12 inches. The trench ran from the back of the garage to the garage’s electric service sub panel. Three underground PVC conduits of utility-grade schedule 80 are located within the 200-foot trench. These conduits are “future-proofed”, and increased in diameter and wire amperage to permit solar and/or battery backup.
- One conduit to carry the garage sub panel feeder wire.
- One conduit to carry the solar feeder wire
- One conduit for the Powerwall backup feeder wire
To ensure that the trench was covered with concrete, we then laid sod.
Another 45 feet of utility grade trenching was added at a depth of 36 inches between the main electrical service at the house panel and the Austin Energy pull box at the street.
One 3-inch PVC conduit in the trench is utility-grade schedule 80. It allows for the upgrade of 320 AMP service feeders that Austin Energy transformers are up the street. We carefully removed, replaced, and returned the sod back to its original condition after trenching.