If you are an electric vehicle (EV) driver, you might already understand what it takes to charge your EV. You have probably experimented with different options to evaluate what fits your lifestyle and requirements best. If you are considering an EV, understanding how to charge should be one of the top priorities before doing so.
The most common reasons for choosing an EV are to reduce your carbon footprint and save money on fuel. Let us explore how you can achieve both.
Energy requirements for the Tesla Model 3
For a Tesla Model 3, we have the standard range, long range, and performance model options. The following are the specifications:
| EV make and model | Battery size (kWh) | Battery acceptance rate (kW) | Vehicle efficiency (mi/kWh) | Average miles driven daily* (mi) | Energy required daily (kWh) |
| Tesla Model 3 Standard Range | 50 | 7.7 | 4.40 | 37 | 8.39 |
| Tesla Model 3 Long Range | 75 | 11.5 | 4.13 | 37 | 8.94 |
| Tesla Model 3 Performance | 82 | 11.5 | 4.10 | 37 | 9.00 |
*The average American drives 13,476 miles annually, or about 37 miles daily.
The table above shows that an average driver would need about 8 to 9 kWh of energy daily to charge their Tesla and meet their daily requirements. We will round it off to 10 kWh daily for all our calculations.
Process of Solar Charging
Driving an electric vehicle is a step towards reducing your carbon footprint. However, the impact is significantly increased when the energy needed to power your EV is sustainably produced. The perfect solution to this problem is to ensure you have a reliable home charging station equipped to draw power from renewable energy sources.
With an Enphase Energy System, the Enphase App can intelligently detect excess solar production and direct that toward EV charging. The Self-Consumption profile empowers you to charge your EV using excess solar energy. Additionally, you can use your home battery for backup purposes or EV charging.
Cost of Solar Charging
Let us start by calculating the variable cost of charging your EV using solar energy. The assumption is that your Enphase Energy System powers 100% of your EV energy needs.
The standard and most popular solar panels are rated for 400 W of power. Considering efficiency and power loss, the maximum continuous power that can be achieved is around 325 W (as per observed data on the field). The average duration of sun powering a home solar system will vary based on where you live, the orientation of your roof, and the time of year. The average data suggests the range to be four to six hours daily.
Using an average of five hours of sun daily:
325 W x 5 hours = 1.625 kWh of energy per panel
To achieve 10 kWh of energy daily for EV charging, the system requires:
10 kWh / 1.625 kWh = 6.15 panels (7 panels for ease of calculation)
This is an approximate home energy system size of:
7 x 400 W = 2.8 kW
To charge a Tesla Model 3 with solar energy, a dedicated system of 2.8 kW is recommended, with an average installed system cost of around $3.30 per watt.
• Therefore, the fixed cost of the home energy system is 2.8 kW x $3.30 = $9,240
• Apply the federal tax credit of 30%, and the cost drops to $6,468. ($9,240 - 30% = $6,468)
Once installed, the Enphase home energy system comes with a 25-year warranty, and the energy produced over that time is used to calculate the dollar rate per kWh:
• $6,468 / (10 x 365 x 25) = $0.07 per kWh of energy produced
So, an average daily commute of 37 miles, requiring about 10 kWh of energy daily, costs about $0.70 daily or $256 per year.
Cost of Grid Charging
The cost of charging an EV using grid electricity varies by utility and state. While some utilities offer specific plans tailored for EV charging, many also provide off-peak and peak rates based on time of use.
To understand the average cost of charging an EV using grid electricity, we will use the national average rate of $0.173 per kWh.
At this rate, charging a Tesla Model 3 for an average daily commute of 37 miles totals $1.73 daily or $631 per year.
Fixed Costs
The IQ 40 EV Charger is the most suitable charging station in the Enphase lineup for a Tesla Model 3 (Standard). Considering the cost of the IQ 40 EV Charger ($622) and installation ($1,000), the fixed price, after the 30% federal tax credit, is about $1,135.
Savings, Savings, Savings!
The average Tesla Model 3 owner’s savings from charging with solar versus grid electricity is about $375 in the first year. The savings increase annually since electricity rates have increased at a CAGR of about 4.3% annually over the last five years. In this scenario, the IQ EV Charger pays for itself within the first few years, with a cumulative savings of $2,158 in the first five years.
Charging your Tesla Model 3 using solar energy produced at home is a significant step toward lowering your carbon footprint while saving more than $2,000 in the first five years. After the third year, every penny saved is more money in your pocket.
