A homeowner in New Jersey has experienced a full year without receiving a traditional electricity bill. The property now runs entirely on energy generated from a Tesla Solar Roof paired with three Powerwall 3 batteries. This integrated system powers various household appliances, computers, televisions, air conditioning, and even an electric car, providing a practical example of how modern renewable technology can transform energy usage at home.
Overview of the System
The installation comprises a fully integrated solution from Tesla. The key components include:
- Tesla Solar Roof – A roof that not only protects the home but also generates electricity.
- Three Tesla Powerwall 3 Units – These provide a combined storage capacity of 40.5 kilowatt-hours.
- Tesla App – A monitoring tool that displays real-time data on power generation, consumption, and battery charge levels.
- Home Charging Station – Used to charge an electric car directly at the property.
| Component | Specification |
| Solar Array Size | Approximately 29.3 kW |
| Battery Capacity | 40.5 kWh (3 x 13.5 kWh per unit) |
| Maximum Battery Output | 15.5 kW |
| Installation Duration | 8 months (from Nov 2021 to Jul 2022) |
This concise and integrated solution has delivered energy independence and reliable backup power during outages.
Installation Process
The installation process was detailed and required careful planning. The journey began in November 2021, with the system becoming operational in July 2022. A dedicated Tesla advisor managed every step of the project. Professionals visited the property to take precise measurements and assess the roof’s suitability. The homeowner encountered several stages including inspection, quotation, and scheduling of the installation. Despite the lengthy process, the benefit of having a system that integrates all components seamlessly has proven to be a worthwhile investment.
How the Solar Setup Works
The solar roof collects sunlight and converts it into electrical energy during the day. When the system produces more power than the home requires, the excess is fed back into the grid. This process, known as net metering, reverses the meter and builds a credit. When sunlight is insufficient—whether due to the night or cloudy conditions—the house draws energy from either the batteries or the grid.
Key operational features include:
- Real-time Monitoring: The Tesla app provides continuous updates on energy production and consumption.
- Automatic Switching: The system seamlessly transitions between solar, battery, and grid power.
- Backup during Outages: In the event of a grid failure, the batteries automatically supply power.
- Energy Management: The app helps to identify peak energy usage times and adjust consumption accordingly.
This setup is designed to meet most of the household’s energy needs during daylight hours. When production falls short, the stored energy in the Powerwalls ensures uninterrupted power supply.
Seasonal Performance
Performance data shows that solar energy generation varies with the seasons. The system adapts to changes in sunlight duration and weather conditions, resulting in fluctuations in energy production.
On sunny summer days, the solar array can generate between 260 and 300 kilowatt-hours. In contrast, on overcast days, production may drop to around 65 kilowatt-hours. During autumn, a typical sunny day produces roughly 120 kilowatt-hours. Winter poses the greatest challenge, with daily production sometimes falling between 20 and 70 kilowatt-hours due to shorter days and frequent cloud cover. The table below summarises the typical daily generation figures:
| Season | Typical Daily Generation (kWh) | Remarks |
| Summer | 200 – 300 | Long, sunny days with occasional clouds |
| Autumn | Around 120 | Cooler temperatures reduce the need for AC |
| Winter | 20 – 70 | Short days and persistent overcast skies |
Financial Aspects
A significant aspect of this project is the financial investment and its payback period. The total installation cost was approximately #120,948.04. However, with a federal tax credit applied, the net expense reduced to around #93,000. Based on estimated annual electricity usage, which would have cost roughly #9,660 using traditional energy sources, the system has an effective payback period of just under 10 years.
Additional financial details include:
- Total Net Cost after Tax Credit: Roughly #93,000
- Annual Savings: Nearly #9,660
- Payback Period: Approximately 9.6 years
- Monthly Account Fee: Around #5.75 (even with near-zero net electricity usage)
The use of net metering allows any excess energy produced during periods of high generation to offset consumption during lower production times. This arrangement helps in maintaining a minimal electricity bill each month.
Additional Observations
The Tesla app has been an essential tool, offering detailed insights into the energy usage and performance of the system. Observations from the first year include:
- Power Outages: During local power failures caused by thunderstorms, the system automatically switched to battery power. Notifications from the app ensured that the homeowner was aware of the change.
- Snow and Ice Management: In winter, the solar tiles remain slightly above freezing. This feature prevents the accumulation of snow on the roof, allowing the panels to continue generating power. However, in cases of heavy snowfall, an insulating layer can form, which may eventually slide off the roof.
Energy Consumption Patterns: The system revealed that the highest energy consumers in the home were the electric car and the air conditioning unit. In contrast, smaller appliances such as computers and televisions had a negligible impact on overall usage.
