How To Build A DIY Solar EV Charging Station

Are you an EV owner/looking to invest in one? If you’ve answered ‘yes’ to either, then you need to consider a DIY solar EV charging station.

With today’s constantly fluctuating electricity prices, it’s only natural that you’d want to become more energy-independent. Or maybe, you just love a good ol’ DIY project. Either way, a DIY solar EV charging station is a no-brainer!

But there’s more — controlling the input electricity for your EV also determines its ‘greenness’. Why? Because, while you may be mitigating tailpipe emissions, your electricity source is still a greenhouse contributor. For example, in the US, 40.7% of electricity is still created from natural gas and 19.4% from coal!

So, in this article, we’ll cover what an EV charging station is, what you’d need to make one yourself and how to set it up.

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What Is A DIY Solar EV Charging Station?

A DIY solar EV charging station is a handmade, self-sustaining power point for your car. It will enable you to run your car on sunshine!

These stations can be on-grid or off-grid — this post will discuss a DIY solar charging station that is linked to an off-grid system.

This means that you won’t be dependent on purchasing any more electricity to charge your EV — after the initial investment you can charge your car for free!

A DIY charging station is the perfect partner for your EV and makes total sense. You’ll have your own independent, secure, and reliable energy source.


Components Needed For A DIY EV Charging Station

The parts you’ll need to create your own charging station include:

  • Solar photovoltaic panels
  • Solar inverter
  • Charge controller
  • Battery
  • EV supply equipment

Additionally, you’ll need to think about where you want to put your solar panels. Will they go on your roof/ garage, or do you need to build another structure?


Working Example:

For our example, we’ll be using this charging station for a Tesla Model Y (top-selling model 2021 in the US). This means that to charge our car from a low battery it would take:

  • 20-40 hours with a level 1 charger (120V home outlet)
  • 8-12 hours with an AC level 2 charger (220/240V)
  • 15-25 minutes with a level 3 charger (480V Tesla Supercharger)

Given that we would not be typically driving your car flat out every day, let’s assume that we’d be driving a reasonable 30 miles per day. This would mean our Tesla would use 7.8 kWh per day, according to a range of 0.26 kWh per mile.

Let’s be conservative here and round this up to 10 kWh per day — just to make sure we have enough power.

We also want to aim for a Level 2 AC charger (240V), as a level 1 charger would take too long and it’d be quite risky to try and install a level 3 charger at home (at 480V and with direct current).


Solar Panels

Solar panel - can be used for DIY solar EV charging station.

These panels use photovoltaic (PV) technology to convert photons from the sun’s rays into electricity. These panels will serve as the energy source for the charging station.

How many panels do we need? Well, if we consider that:

  • From our 10 kWh/day for our Tesla, we’d need around 16.67 kWh/day in solar energy. We must consider around +50% power requirements (industry standard) and 90% battery and inverter efficiency.

So, to obtain our goal of 10 kWh a day, we’d need 11 solar panels. Given that each 400W panel will cost you around $300 each, this would set you back $3,300.

We’ll be using 400W solar panels, as they are an outstanding balance between yield and price, as seen in our solar carport post.

To learn more about 400W solar panels, you can read our article here.


Solar Inverter

Inverters for solar panels are a key part of your system. They allow your solar panels to power your electronic devices by converting DC (Direct Current) electricity into clean AC (Alternating Current). Similar to the electricity from your utility company.

You’ll need an inverter as the output power of a solar panel is constantly fluctuating over the course of the day and is strongly correlated to the weather (passing-by clouds, rain, full sun, etc). Because of these fluctuations, all inverters for solar panels include an MPPT solar charge controller that’ll optimize solar production.

The type and size of the inverter will depend on your preferences and setup. In summary, there are three types of inverters:

  • Micro-inverters (Grid-tie)
  • String inverters (Grid-tie)
  • Hybrid inverters (Off-grid)

To choose the most ideal inverter, check out our article — 3 Types of Inverters For Solar Panels.


Charge Controller

A charge controller will regulate the power output of your solar panel and properly charge the battery.

There are currently 2 types of solar charge controllers: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking).

To choose the most ideal inverter, check out our article — How To Select The Correct Solar Charge Controller.


Battery

Tesla PowerWall - can be used for DIY solar EV charging station.
Tesla PowerWall.
Source: Tesla.

Store your PV energy in batteries — they are your key to autonomy. Lithium batteries are recommended. Although more expensive than lead-acid, they’re perfect for intermittent charging and durable, with up to 10 years of service.

You’ll need batteries to store the sun’s energy, as you’ll probably be using the car during the day and charging at night.

Battery Cost & Choice

Battery prices are the most expensive component for your DIY charging station.

For our Tesla Model Y, we would need 3-4 24V 100Ah Lithium batteries or 6-7 lead-acid batteries. We have estimated this through the following calculation process:

  1. Convert our Wh to Ah: 4170Wh / 24V = 173.61 Ah
  2. Calculate required battery capacity depending on Depth of Discharge of battery technology (50% for lithium and 25% for lead-acid). Let’s go with lithium, so we divide our Ah by our DoD: 173.61 / 0.5 = 347.22 Ah capacity

The best battery for your needs depends on whether you’re going to use it for your EV, or if it’ll be part of a larger system.

If you want to see a comparison of lithium batteries, check out our article on the best lithium batteries for boats — these are applicable for home use too.

You may also want to consider a PowerWall for your charging station — consider Tesla’s one or make your own one. For the battery, you’ll need around $10,000.

If you’re interested in learning more about what you can power with batteries at home, please check out our article on What Can I Run Off A 100Ah Battery?


EV Supply Equipment

EV supply equipment - can be used for DIY solar EV charging station.

EVs are not designed to be charged directly from solar panels or batteries. You would need to use proper equipment for this in order to make it safe.

EV supply equipment (EVSE) basically consists of all electrical equipment and software necessary for efficiently and safely delivering energy to your EV.

EVSE is classified according to the charging levels.

As mentioned previously, our aim is to go for a Level 2 AC (240V) charging system.


Breakdown Of Inventory And Costs

Below are expected material costs for a solar EV charging station.

You can install the panels onto a carport, an external area, or on top of your house. As such, you’ll need to account for these further costs and structural/ mechanical requirements.

Please keep in mind that you may need professional installation and setup help — this will also incur further costs.

ItemNumberCost
Solar Panel11$3,300
Solar Inverter1$1,000
Charge Controller1$800
Battery1$10,000
EV Supply Equipment1$3,000
Miscellaneous (cables etc.)$200
TOTAL $18,300

So as a ballpark figure, you can see that driving around 30 miles a day with our Tesla Model Y will require around 18,000 USD.

This will vary depending on your setup but please keep in mind that the key variables here are:

  • How many kWh you will need per day (driving range and EV type).
  • How much space you have for solar panels, and will you need an additional structure.
  • What type of battery technology you want to use.

Assemble Your DIY EV Charging Station (Step-By-Step)

The Assembly of your charging station is relatively simple. If you aren’t comfortable with any aspects, consult a professional.

The key steps for assembly are:

  1. Structural installation — Plan and install any structural elements you may require for your solar panels, batteries and other components. If you’re looking to build a carport, check out our post – How To Build A DIY Solar Carport (Complete Guide).
  2. Electrical installation. Install and connect all electrical components mentioned.

Final Thoughts

Making your own DIY solar charging station is a great clean energy investment. It would make you independent from the grid, and could potentially save you in the future against continually increasing electricity prices.

The type of charging station you would need would depend on:

  • EV type
  • Average daily distance traveled
  • Battery system

Also, keep in mind that the main costs for your DIY solar charging station would be due to:

  • Number of solar panels (how much juice you’ll need and your local solar irradiation level) and if you need any additional structures.
  • How much electrical storage capacity you’d need.

Feel free to reach out to us in the comment section below if you have any further questions!

Thomas Mattinzioli

Thomas Mattinzioli

Tom is a civil engineer, specializing in sustainable transportation infrastructure. He has worked for over 4 years in sustainability and research. Sustainable transportation and alternative fuel vehicles are among his specialties.

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Colin

Can you expand on how you determined how many solar panels are needed?

I worked backwards and it seemed like you followed the logic of

16.66kWh/day < 11 panels * 400W/panel * 4kWh/m2/day = 17.6kWh/m2/day

but these units make no sense. The resulting units of the product would be kWh/m2/day, not kWh/day. What am i missing?

Kyle Browning

Hey Colin, you are correct, thanks for pointing out that typo. We have rectified the units to read: kWh/kWp per day.

hrjjml

This is not so worth it.
When are going to recover the $18,300 investment?

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