Tesla solar charger: How much does it cost to charge a Tesla using solar energy?

Tesla EV in front of solar panels

Following the news of Tesla’s acquisition of U.S. solar installer giant SolarCity, the world has been keeping a close eye on Elon Musk and his two prosperous clean energy ventures. Tesla and SolarCity, electric cars and solar panels – a two-front war waged against grid reliance and energy dependence. In 2018, Musktopia is both expanding and constricting as two of the tech entrepreneur’s five companies are joining forces around one common goal: decimating your carbon footprint.

How to Charge a Tesla with Solar Energy

Many homeowners are wondering if they can charge their Tesla car with solar panels and the answer is you can. An electric vehicle such as a Tesla can serve as battery storage for solar energy. Musk has outlined his newest goal, which he says can be achieved with his one-two punch solution for homeowners seeking alternatives to fossil fuels:

  1. Install solar on your roof to generate electricity by harnessing the power of the sun
  2. Take that photovoltaic energy and use it to charge your Tesla Model S

Was this all possible before the Tesla-SolarCity merger? Of course. A Chevy Volt or Nissan Leaf owner didn’t need Elon Musk’s “master plan” to realize that electric cars can be paired with solar energy. But perhaps Musk’s true innovation was in recognizing that solar panels and electric cars are complementary, not substitute, goods and need to be marketed as such.

You might be able to imagine a world where a tablet and a smartphone are viewed as substitute products, but Steve Jobs successfully reached beyond tech’s power-users and created a need for both to exist in mainstream markets. Similarly, Musk’s latest move targets the layman homeowner, extending beyond clean energy’s early adopters who paired their Leaf or Volt with home solar panels years ago.

Elon Musk with solar panel tesla battery

By bringing two of the world’s leading solutions to emissions reduction under one roof, Tesla can cut operating costs in development and installation, helping homeowners to understand clean energy financing options as a combined cost rather than trying to conceptualize the headache of multiple individual energy investments. In a sense, Tesla is making clean energy simple because it needs to be simple.





tesla solar graphic




With this merger underway and with millions considering the prospect of a zero emissions home, a number of questions are arising in the renewable space. How do you connect solar panels to an electric vehicle? How long will it take for solar panels to charge a car? How many panels will you need to charge your car in the first place? These are some of the issues Musk hopes to solve with one all-encompassing mega brand. Now that Tesla has been unquestionably established as a clean energy behemoth for the future, it’s time to explain what this all means for the carbon-conscious homeowner in a world where going solar or going electric has been merged into a more Musk-approved, illustrious phrase of “going zero” (emissions).

How many kWh does it take to charge a Tesla Model S?

In order to understand how solar panels and Tesla vehicles complement each other in Musk’s vision, we first need to understand how electric cars are charged rather than fueled. And because solar panel systems are sized based on the expected energy usage of a household, a homeowner would need to take into account projected energy needs from his or her Tesla in order to get a solar panel system that can generate enough electricity enough to meet that combined demand.

The cross-functional metric to use here is kilowatt-hours (kWh), which represents the amount of energy used while kW would refer to available capacity. In order to compare electric vehicles (EVs) to automobiles, the EPA uses the amount of kilowatt-hours required for an EV to travel 100 miles as a miles per gallon equivalent (MPGe).

According to FuelEconomy.gov, the 2018 Tesla Model S requires 33 kWh per every 100 miles, giving it a fuel economy rating of 103 MPGe (combined city and highway). Thus, if the ultimate question is how many kWh it will take to charge your Tesla, it will depend on the distance you plan to travel. A short trip 25 miles each way would require roughly 17 kWh of energy, while the energy needed to run errands around town might only require 2 or 3 kWh.

How many solar panels does it take to charge a Tesla?

Now that it’s clear how much energy a Tesla vehicle will require, the next step is to calculate how many solar panels are required to provide that charge and fulfill the Musk doctrine of going completely zero emissions in one fell swoop. Because solar panel electricity production is dependent on a few different factors, we’ll use an example homeowner who already has solar but wants to know how many more panels it will take to supply energy for a 2018 Tesla Model S. Let’s call her Barb.

Barb has a 5 kW (5,000 watt) solar system, the average system size for the U.S. residential solar market. She lives in Cleveland, Ohio where solar is not unusually cheap or particularly expensive. In Cleveland, the average annual energy production for 5kW solar systems is 6,071 kWh, which means that every year Barb’s solar panels are producing that much energy. Assuming Barb’s system uses standard 250-watt panels, we then also know that Barb’s current solar array has 20 solar panels (250 W x 20 panels = 5,000 W). This means that each of Barb’s panels produces just over 303 kWh of energy in a year (6,071 kWh/20 panels). Let’s think of this number as Barb’s annual energy production for a single panel.

 

electric car charging stations

 

How much will it cost to charge a Tesla with solar panels?

As we learned above, Barb’s new Tesla Model S has a 33kWh/100 MPGe rating. If we assume she will be driving 25 miles a day, we then know her Tesla is going to be using 8.25 kWh a day (3,011 kWh per year). Then – stay with me here – we can use our prior annual energy production value of 303 kWh/year and determine that Barb will need to add roughly 10 more solar panels to her system in order to completely cover her new Tesla and receive the seal of zero emissions approval from Mr. Musk.

The next question might be “how much does it cost to charge a Tesla with solar” or in other words, how much extra will Barb need to pay for those 10 panels. If we assume an average price for a standard panel is $185, charging Barb’s brand-new Model S will likely tack on another $2,000 to her solar panel system costs. Compare that to total money spent at the gas pump every year and we start to see why pairing a Tesla with solar panels makes sense. In the long run, Barb will see concrete energy savings on multiple fronts, and will likely break even on her solar panel investment in seven to 10 years.

Tesla solar charging stations and Tesla Powerwall

Tesla model S at solar charging station

If you’ve been following Tesla for some time, the acquisition of SolarCity should not have come as a shock. Tesla car charging ports with overhead solar canopies (as seen in the image above) have become a common sight in Europe and America, and the Tesla Powerwall is really the only solar battery brand that homeowners can cite by name. The Powerwall has seen numerous hurdles and criticism. However, Tesla successfully got the attention of mass consumer markets in bringing to light the benefits of solar-plus-storage as a highly efficient alternative energy solution. Tesla now needs only to sit and wait while its brand blows past the competition.

tesla_charging_station

Tesla Motors Wall Connector w/ 24′ foot Cable Charging Station

Out of Musk’s “Masterplan Part Deux” came a plan for Tesla to launch other electric vehicle models, including trucks and minivans, as well as a clean energy rideshare offering. We can expect the number of solar powered charging ports to explode in coming years. Even now, you can purchase Tesla branded wall-mounted charging stations for your home – an option that is sure to become more popular as the Tesla Model 3 hits the road across the country. These sleek, all-renewable power stations are a visual representation of Tesla’s mission as a corporation and their role will see dynamic value under the new era of Tesla.  

In a sense, the merger is just an upgrade of prior solar projects that Tesla flirted with in order to brand itself as a renewable energy company rather than a car company. The groundwork has long been in place for Musk’s clean energy integration – with the the Powerwall, electric cars, and images of Tesla’s new, rebranded solar panel design already surfacing online, Tesla is fully and openly bringing its sleek, luxurious touch to the solar industry. While many were surprised by the acquisition, some are wondering why it took so long. Those same people might also be anticipating the day when “Musk” is officially deemed a synonym for the word “innovation” in the English language.   

How to find the best deal on solar

For those planning to go all in on clean energy, hopefully this breakdown helped you to envision the integration of solar and EVs. The next step towards zero emissions is to begin searching for the right EV and start comparing quotes for a solar panel system. The EnergySage Solar Marketplace allows you to compare real pricing data from homeowners in your area and review various financing options for free. For those looking for a personalized instant estimate for solar, try our Solar Calculator (recently recommended by Consumer Reports).





Don



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11 thoughts on “Tesla solar charger: How much does it cost to charge a Tesla using solar energy?

  1. Mark Richardson

    I am curious why you chose Cleveland, OH for your cost-comparison, as that area gets a lot of rain. In-fact Cleveland has just slightly less than 50% rainy days annually. Just looking at our solar production here in Metro-Denver, a city with about 300 sunny days annually, from our 4000-watt system, which was new in 2014, during March, 2018 we produced 1,001.85 KwH, or an average of 32.31 KwH/day.

    We sold a fair amount of our production back to our power utility in-fact. So at-least for our system, its age, and location, each 250-watt panel produced 62.615 KwH/month. If your figure for the electric consumption of 8.25 KwH/25 miles is acccurate, then we only need to replace any amount over what we are selling back to our power utility now.

    Another question I have concerns your estimated payback period. Now let’s assume that your gal in Cleveland drives 25 miles daily on local city streets there, which during rush periods are slow to stop & go there due to non-snychronized traffic lights. Including having to start her engine at least 4 times per-day her fuel use is likely 1.5 to 2 gallons at a retail cost of close to $3.00/gallon.

    So just her fuel use daily is $4.50 to $6.00, plus the cost of 4 oil changes annually, let’s say $182.50, which works out another 50 cents per-day. Now most other operating costs are similar between gasoline-powered vehicles and EVs except the cost of tune-ups, air filters, oil filters (included in oil changes), and fuel filters, plus any fuel or exhaust system repair or replacement.

    Let’s assume one new muffler every 4-6 years of operation (more in Cleveland because of road salt), plus at-least a couple cans of fuel injector cleaner, plus 2-3 new air filters per-year, plus at-least 1-2 new fuel filters during the life of the vehicle. Gawd forbid you have to replace your fuel pump, fuel tank, oil pump, oil pan, catalytic converter, fuel injection system, or engine as any of these items will raise your cost of operating your gas-engine car considerably.

    Let’s just assume a total fuel and exhaust system operating cost for a gasoline-powered vehicle doing 25 miles per-day in Cleveland, not including depreciation, of $6.00 to $7.50 per-day, or 24 to 30 cents per-mile.

    Now using your stated costs for 250-watt solar panels of $185, times 10 panels is $1850. I will even add the cost of the charger at $150, which makes $2000. Let’s assume you drive your car 25 miles per-day, which works out to 9,125 miles per-year and that you drive your car for 10 years before trading it in.

    New solar panels today have a 30-year guarantee at 95% efficiency so let’s just assume 100% efficiency for 30 years. So your cost to charge your vehicle for 10 years is only 1/3rd the cost of the solar panels and the charger, or $667. If we divide that number by 10 (years) we get $66.70, and if we divide this figure by 365 (days) we get 18.2 cents per-day, or 0.73 cents per-mile.

    Here in Denver the cost to charge the car using rooftop solar is about 1/3rd of what the cost is in Cleveland or less depending on how much power you are already selling to your public utility.

    So even in Cleveland, charging your EV off your own rooftop solar power system is only 2.5 to 3.33% of the cost of operating a gasoline-engine car and in Denver the EV solar power charging cost is just 1/3rd of what the cost is in Cleveland.

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