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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Table of Contents
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
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:
- We would get around 4 kWh/kWp per day in the middle of the US, in this example. This will change depending on where you are — check out how much you would get here.
- 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
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:
- Convert our Wh to Ah: 4170Wh / 24V = 173.61 Ah
- 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
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.
| Item | Number | Cost |
| Solar Panel | 11 | $3,300 |
| Solar Inverter | 1 | $1,000 |
| Charge Controller | 1 | $800 |
| Battery | 1 | $10,000 |
| EV Supply Equipment | 1 | $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:
- 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).
- 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!
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?
Hey Colin, you are correct, thanks for pointing out that typo. We have rectified the units to read: kWh/kWp per day.
This is not so worth it.
When are going to recover the $18,300 investment?
It’s very case dependent based on your driving needs, range of travel, where you live, and current cost of electricity. If you don’t drive much then yes it would be a waste of money. However, if you’re traveling a lot within a fairly local radius and plenty of sunshine then it would be extremely worth it. Not a lot of travel then sure it would take a long time to pay it off. For example I think my dad is a great case of where it would be extremely beneficial. He has to drive within a 50 mile radius of his house and probably drives 100+ miles a day 365 in his work truck and has to haul tools around in case something breaks at his work sites. So, if my math is correct:
100 miles per day.
16-21mpg for his truck so we’ll round to 18mpg.
100/18mpg = 5.5 gallons of fuel per day.
$3.50 per gallon gasoline x 5.5 gallon = $19.25 per day
$19.25 per day x 313 days he doesn’t really ever take off but I am giving him a day off a week = $6103
After 3 years he would be essentially be getting free fuel and I’m being very conservative with how much he drives, I think he puts on closer to 150 miles a day on his truck since he puts somewhere at around 50000-60000 miles per year on his truck.
Can’t compare gas to electricity. What he means is 18000. In solar vs buying power from the grid a kwh is about 0.15. So return on your 18000.00 is 120000 kwh of power or 12000 days of changing your car using 10kwh of power.
Could this work without the battery for direct trickle charging from the array? Used low cost solar panels are widely available so could be an affordable project without the $10k battery.