An EV adds 3,000–5,000 kWh/year to your electricity usage, requiring an additional 2–4 kW of solar. Combined with a TOU rate strategy, solar + EV can save $2,000–$4,000 annually on transportation + electricity.
Avg EV Usage
3,400 kWh/yr
12K miles, mid-size EV
Extra Panels Needed
2.6 kW
6 panels @ 430W
Gas Savings
$1,750/yr
vs 28 mpg @ $3.50/gal
Level 2 Charger
$1,000–$2,700
unit + installation
How Much Energy Does an EV Use?
| Vehicle Type | Efficiency | 12K miles/yr | Additional Solar |
|---|---|---|---|
| Small EV (Nissan Leaf, Chevy Bolt) | 3.5–4.0 mi/kWh | 3,000–3,400 kWh | 2.3–2.6 kW |
| Mid-size EV (Tesla Model 3, Hyundai Ioniq 6) | 3.0–3.5 mi/kWh | 3,400–4,000 kWh | 2.6–3.0 kW |
| Large EV/SUV (Tesla Model X, Rivian R1S) | 2.0–2.5 mi/kWh | 4,800–6,000 kWh | 3.7–4.6 kW |
Complete Solar + EV Sizing Calculation
Let's walk through a complete sizing calculation for a Connecticut homeowner buying a Tesla Model 3. Current home usage is 10,000 kWh/year. The Model 3 will be driven 14,000 miles/year at 3.2 mi/kWh efficiency.
Calculate EV charging load
14,000 miles ÷ 3.2 mi/kWh = 4,375 kWh/year. Total household usage = 10,000 + 4,375 = 14,375 kWh/year
Determine system size
Connecticut has 4.8 peak sun hours per day. System size = 14,375 kWh ÷ (4.8 hours × 365 days × 0.80). System size = 14,375 ÷ 1,401.6 = 10.26 kW
Convert to panel count
Using 430W panels: 10,260W ÷ 430W = 23.86 → 24 panels (10.32 kW system)
Calculate cost
Connecticut pricing is $3.15/W. 10,320W × $3.15 = $32,508 before incentives. CT RSIP rebate: 10.32 kW × $0.25/W × 1,000 = -$2,580. Net cost: $29,928
Compare to gas vehicle costs
A gas vehicle at 28 mpg driving 14,000 miles uses 500 gallons/year. At $3.50/gallon, annual fuel cost is $1,750. The Tesla uses 4,375 kWh/year. If charging from the grid at $0.22/kWh, annual cost is $962. Solar charging is effectively free (marginal cost of solar production is $0). Total 25-year savings vs gas: $1,750 × 25 = $43,750.
Cost Comparison: Gas vs Grid vs Solar Charging
Using the example above (14,000 miles/year, Tesla Model 3 at 3.2 mi/kWh):
Gas Vehicle
28 mpg, $3.50/gallon
EV Grid Charging
$0.22/kWh
EV Solar Charging
Marginal cost = $0
25-Year Savings: Gas vs Solar EV
$47,500
Annual savings: $1,900/year. The $29,928 solar system pays for itself in 15.7 years from EV savings alone, not counting the 10,000 kWh of home usage it also offsets.
Level 1 vs Level 2 Charger: Which Do You Need?
Level 1: Standard 120V Outlet
This is the charger that comes with every EV. Plug it into any standard outlet. Level 1 works if you drive less than 30 miles/day and can charge overnight every night. For most drivers, Level 1 is too slow.
Level 2: 240V Dedicated Circuit
Requires an electrician to install a 240V/50A circuit (same as a dryer or oven). Level 2 is the standard for home charging. You can fully charge overnight even after a 200-mile road trip.
Which charger to buy: Most EVs come with a Level 1 charger. You buy a Level 2 charger separately ($500–$1,200 for the unit + $500–$1,500 for installation). Popular models include ChargePoint Home Flex ($699, 50A, WiFi), JuiceBox 40 ($599, 40A, WiFi), and Tesla Wall Connector ($450, 48A). If you have a Tesla, get the Tesla Wall Connector. For all other EVs, ChargePoint or JuiceBox offer the best combination of features and reliability.
TOU Rate Strategy: Charge Smart
If you have time-of-use (TOU) rates, solar production peaks when rates are highest (midday). Charge your EV during off-peak hours (overnight) and let solar credits offset your peak usage for maximum savings.
- With net metering (1:1 retail): Charge anytime — your credits offset the cost regardless.
- With TOU rates: Export solar during peak ($0.25–$0.40/kWh), charge EV off-peak ($0.08–$0.12/kWh).
- With net billing: Charge during solar production hours to maximize self-consumption.
TOU Optimization Example: Massachusetts Eversource
Massachusetts TOU Scenario
Eversource offers a TOU rate with peak ($0.38/kWh, 4–9pm), mid-peak ($0.26/kWh, 9am–4pm), and off-peak ($0.14/kWh, 9pm–9am). Your solar system produces 40 kWh on a typical day, all during mid-peak hours. Your home uses 20 kWh mid-peak (covered by solar) and 15 kWh peak (from grid). You export 20 kWh of excess solar to the grid during mid-peak.
Without TOU Optimization
$15/month, $180/year
With TOU Optimization
$57/month, $684/year earnings
By shifting discretionary loads (EV charging, laundry) to off-peak and exporting solar at mid-peak, you turn a $180/year cost into a $684/year earnings. That is an $864/year swing from one behavioral change.
Panel Capacity and Electrical Service Upgrades
Adding an EV charger increases your home's electrical load. A Level 2 charger draws 7–11 kW (30–50 amps at 240V). If your home has a 100-amp main panel and existing loads of 60 amps (HVAC, appliances, lights), adding a 50-amp EV charger exceeds the panel capacity.
Two solutions: (1) Upgrade to a 200-amp panel ($2,000–$4,000), or (2) Install a load management device like the Span Panel ($4,500) that intelligently shares capacity between the EV charger and other loads. The Span Panel monitors your home's load in real-time and throttles the EV charger if other loads are high, preventing circuit overload.
If you are installing solar and an EV charger simultaneously, coordinate with your electrician to assess panel capacity. Many homes built before 2000 have 100-amp panels insufficient for solar + EV + heat pump. Bundling the panel upgrade with solar installation saves on permitting and labor costs.
Combined Solar + EV Savings
EV vs Gas Savings
$1,200–$1,800/yr
Driving 12,000 miles/year in a mid-size EV saves this much vs gasoline @ $3.50/gal.
Solar Charging Savings
$400–$800/yr
Charging from solar vs grid electricity adds this much additional savings.
Total Annual Savings
$1,600–$2,600
Combined solar + EV delivers this much in total annual savings vs gas vehicle + grid electricity.
Level 2 Charger Installation
- Charger unit: $500–$1,200 (ChargePoint, JuiceBox, Tesla Wall Connector)
- 240V outlet installation: $500–$1,500 (electrician runs new circuit)
- Panel upgrade (if needed): $2,000–$4,000 (older homes with 100A panels)
- Bundle with solar: Many solar installers offer discounted EV charger installation when combined with solar.
Real-World Case Study: The Martinez Family
New Jersey Two-EV Household
The Martinez family in New Jersey drives a Tesla Model Y (2.8 mi/kWh) 15,000 miles/year and a Toyota Camry (30 mpg) 10,000 miles/year. They want to replace the Camry with a second EV and go solar. Current home usage is 11,000 kWh/year.
Total Load Calculation
Model Y: 15,000 mi ÷ 2.8 mi/kWh = 5,357 kWh/year
Future second EV (Hyundai Ioniq 6, 3.4 mi/kWh): 10,000 mi ÷ 3.4 = 2,941 kWh/year
Total EV load: 8,298 kWh/year
Total usage: 11,000 + 8,298 = 19,298 kWh/year
System Sizing
New Jersey has 5.0 peak sun hours.
System size = 19,298 ÷ (5.0 × 365 × 0.80) = 13.21 kW
Using 430W panels: 13,210W ÷ 430W = 30.7 → 31 panels (13.33 kW)
Cost and Savings
NJ pricing: $3.05/W × 13,330W = $40,657
NY-Sun rebate: 13.33 kW × $0.20/W × 1,000 = -$2,666
NJ state tax credit (25%, max $5,000): -$5,000
Net cost: $32,991
Annual Savings Breakdown
Camry gas: 10,000 mi ÷ 30 mpg × $3.50/gal = $1,167/year
Second EV grid charging savings: 2,941 kWh × $0.19 = $559/year
Home electricity: 11,000 kWh × $0.19 = $2,090/year
Model Y grid charging: 5,357 kWh × $0.19 = $1,018/year
Total annual savings: $4,834/year
Payback Period
6.8 years
25-Year Savings
$120,850
The Martinez family achieves complete transportation and home energy independence for a $33,000 upfront investment.
Size Solar for Your Home + EV
Our calculator accounts for EV charging when sizing your solar system.