Electricians Scott Millette and Brian Ritz, with Peck Electric (based in Burlington, Vermont), install a Tesla Powerwall in a Vermont house as part of a Green Mountain Power pilot program.
Electrician Scott Millette positions and fastens a mounting bracket for a SolarEdge inverter on the wall of a Vermont home.
Electricians Scott Millette and Brian Ritz of Peck Electric (South Burlington, Vermont) carry a Tesla Powerwall, still in its crate. The unit weighs 214 lbs.
Using a motorcycle jack, electricians Ritz and Millette position the Powerwall battery into place. The battery is hung from clips on the mounting bracket.
Ritz removes the shipping crate from the unit. 2-by blocking used for packing (shown against the wall) is removed.
The upper part of the inverter (where it converts DC to AC) has a large, heat-sink plate on the back of the unit. The bottom of portion acts as a communications hub.
Ritz and Millette set the SolarEdge inverter onto its mounting bracket. The inverter converts direct current (DC) from the Tesla battery into alternating current (AC) for use by the home or for transmission into the Green Mountain Power distribution network.
Millette lays out a location for the system's autotransformer unit. The minimum clearance between components is 4 inches, this to allow for ventilation and access to equipment when wiring.
Millette peels the protective shrink-wrap from the face of the Tesla Powerwall battery unit.
Holding the transformer in place, Millette and Ritz trace the location on the wall. In service, the automatic transformer will balance the voltage and create a neutral when backed-up circuits running off battery power. The transformer enables the system to supply a consistent 120 volts to backed-up circuits, explained Millette. Without it, circuits would only have 240v and the power would fluctuate.
Ritz holds the mounting hardware for the transformer unit. For the most part, toggle anchors with bolts through washers are used to attach the components to drywall (the Tesla mounting bracket was the only one that required attaching into framing).
Ritz secures the transformer to the mounting plate while Millette positions the system's smart meter enclosure.
After boring out a hole in the inverter’s enclosure, Millette attaches a conduit fitting to the inverter.
Millette fastens the mounting plate for the smart meter enclosure to the wall.
Millette attaches a conduit fitting to the smart meter enclosure. The StorEdge meter works in tandem with the inverter, sensing whether the system is producing or demanding power. Two circuit transformers or CTs (in plastic bag sitting on top of the housing) are installed on either side of the meter to monitor the amperage passing through the system.
Millette runs flexible, nonmetallic conduit between the inverter and smart meter, as well as the inverter and transformer.
The remainder of the wiring needs to shielded with metal conduit (EMT). Here, Millette begins bending the nickel-coated steel conduit for the connection from the inverter to the backed-up load center.
Ritz installs a 30-amp breaker, which acts as the main disconnect for the backed-up load center. This subpanel houses the critical circuits, such as the refrigerator, key lighting, receptacles, and network communication hub.
Millette installs EMT conduit from the load center’s subpanel to a junction box in the ceiling for the backed-up circuits. Critical circuits are re-routed from the main distribution panel to this point.
Ritz connects circuit breakers in the load center panel (left photo). Circuits in the load center (right photo) serve backed-up loads when utility service from the street is interrupted. An automatic switch in the SolarEdge inverter disconnects the house from utility power and connects the load center to the battery in that situation.
Millette begins wiring the smart meter by connecting the three-conductor, light-gauge RS485 communication circuit. The StorEdge meter handles communication with the utility and facilitates real-time remote control of the system.
Millette bores a hole in the StorEdge meter enclosure so he can route a power feed to the meter from the existing distribution panel.
Millette snakes the power feed. Though the home doesn’t have PV solar, he upsizes the feed to #8 cable to accommodate any future solar modules (the power feed will have to carry a 30-amp load, as well as any production current from a PV array).
Ritz runs Cat-6 wire from the inverter’s hub to a modem in the homeowner's home office. Ethernet (Cat-5, Cat-6), WiFi, or 4G cellular are available for local network communication, though ethernet provides the most reliable connection. From the home’s modem, power company technicians can remotely communicate with and control the battery and the inverter. It alerts them to any performance issues, malfunctions, as well as allowing for routine firmware installations.
The installation process takes a three-man crew about a day and a half to complete. By the end of the first day, all the components have been installed and the bulk of the wiring has been completed. They’ll come back the next day and finish the wiring, then initiate the set-up programming, which occurs at the inverter’s menu window.