A 30-panel solar system in Spain can fully charge a typical electric car battery in around 4-5 hours.
But the exact number of panels depends on:
- Your car’s battery size
- Your system’s output (in kW)
- Whether you’re charging during the day or at night
What You Need to Know Before Calculating Panels
Most people ask how many panels they need. The better question is: what size system (in kW) do you need? Panel count follows from that.
The standard panels we install today output 650W each. Some clients choose all-black panels for aesthetic reasons – these output 420W each.
The difference matters:
- A 20kW system using 650W panels needs 31 panels
- A 20kW system using 420W panels needs 48 panels
Same power output. Very different panel counts.
What Size Solar System Do You Need to Charge an Electric Car?
The size of system you need depends on your car’s battery capacity and how quickly you want to charge it.
In our experience, a 20kW solar system is the most practical starting point for clients who want to charge their car primarily from solar during the day. A 15kW system is a workable middle ground. A 10kW system will make a contribution – but it won’t fully charge most modern EV batteries in a single day.
| System size | Panels (650W) | 60 kWh battery | 80 kWh battery |
|---|---|---|---|
| 10kW | 16 panels | ~6 hrs | ~8 hrs |
| 15kW | 23 panels | ~4 hrs | ~5.5 hrs |
| 20kW | 31 panels | ~3 hrs | ~4 hrs |
How do you calculate the number of panels?
Take your car’s battery capacity and divide it by your system size in kW. That tells you how many hours you need to charge – for example, an 80kWh battery on a 20kW system needs 4 hours. Then divide your system size by the panel power rating. If you’re using panels with 650W (o 0.65kW) then a 20kW system needs 31 panels.
Let’s look at the two steps to this calculation again.
Step 1 — How many hours to charge your car:
| Step | Calculation | Example (80 kWh battery, 20kW system) |
|---|---|---|
| Car battery capacity | — | 80 kWh |
| Hours needed | Battery ÷ System kW | 80 ÷ 20 = 4 hours |
Step 2 — How many panels for that system:
| Step | Calculation | Example (20kW system, 650W panels) |
|---|---|---|
| System size | — | 20kW |
| Number of panels | System kW ÷ 0.65 | 20 ÷ 0.65 = 31 panels |
The formula:
- Car battery (kWh) ÷ system size (kW) = hours to charge
- System size (kW) ÷ 0.65 = number of 650W panels needed
Run the same figures for a 15kW system and a 60kWh battery: 60 ÷ 15 = 4 hours, and 15 ÷ 0.65 = 23 panels.
How Long Does It Take to Charge an Electric Car With Solar Panels?
It depends on your charger setting and your system size. The table below shows estimated charge times for typical EV batteries across common solar system sizes – assuming you’re charging during daylight hours from live solar output.
| System Size | 60 kWh Battery | 80 kWh Battery |
|---|---|---|
| 10kW | ~6 hours | ~8 hours |
| 15kW | ~4 hours | ~5.5 hours |
| 20kW | ~3 hours | ~4 hours |
| 22kW charger (max output) | ~3 hours | ~4 hours |
Charge times are approximate and assume consistent solar output during peak sun hours. Source: Huawei FusionCharge.
Spain’s Costa del Sol and Costa Blanca receive around 6 hours of peak sun per day in summer. In winter, that drops significantly – and so does your charging window.
What if my car can’t accept 22 kW?
Many EVs have an on-board charger limited to 11kW. A Huawei 22kW charger connected to one of these cars will only deliver 11kW – effectively doubling the charge times shown above. This is really important to check before sizing a solar installation.
Only a few EVs can accept the full 22kW AC input.
What EV Charger Settings Can You Use With a Solar System?
Most EV chargers have three power settings:
- 7kW
- 11kW
- 22kW
The setting you can use depends on your property’s power supply – not just your solar system.
What is the difference between single-phase and three-phase supply?
Single-phase supply – standard in most Spanish homes – caps your solar installation at 11kW. You cannot install above 11kW on a single-phase connection.
Three-phase supply allows for up to 22kW and more. A property with a large solar system generating at that level could fully charge a typical electric car battery in 3-4 hours. But it would require no other high-power appliances being used at the same time – such as ovens, multiple AC units, pool heaters, heat pumps, etc.
It would be difficult to fully charge an electric vehicle battery in a single day in winter. On the Costa del Sol, peak solar hours in December can be as low as 4.2 hours per day.
Here is a practical comparison of each setting:
| Charger Setting | Phase Requirement | Approx. Charge Time (60kWh battery) | Best Use Case |
|---|---|---|---|
| 7kW | Single-phase | ~8.5 hours | Topping up |
| 11kW | Single-phase | ~6 hours | Topping up |
| 22kW | Three-phase only | ~3 hours | Fully charging |
Charge times based on Huawei guidance for a 60kWh battery at ~90% charging efficiency. Source: Huawei FusionCharge.
Which EV Charger Should You Install With a Solar System?
The right charger depends on whether you already have a solar installation and which inverter brand you’re running.
When we install EV chargers for clients with Huawei solar inverters, we recommend the Huawei FusionCharge. The integration between the charger and the inverter is excellent. The charger communicates with the solar system and knows how much power is available at any given moment – it will not draw more than the system can supply.
For clients without a solar installation, we typically install a Zappi or Wallbox charger.
Can you use a Tesla Wall Connector or Porsche Wallbox with a solar system?
Yes. Marblanc Solar is a partner installer for both Tesla and Porsche to install their branded chargers – the Tesla Wall Connector and the Porsche Wallbox.
These chargers are fully compatible with a solar-powered property. They do not integrate directly with a solar inverter in the same way a Huawei charger does, but they work well as standalone installations on solar homes.
Does It Matter Where You Install Your EV Charger?
Placement is one of the most practical decisions in any EV charger installation. It’s something I consider very carefully whenever quoting for a system.
The charger has to work for daily use. The most common mistake is installing it in a technically convenient spot that turns out to be awkward in practice – requiring the client to park at an unusual angle every single time they charge.
We plan the placement so the client can pull in naturally and connect without inconvenience. The goal is a setup they’ll use comfortably every day without thinking about it.
Can You Charge Your Electric Car Entirely From Solar?
In theory, yes. In practice, most clients supplement their charging rather than replace grid electricity entirely.
To charge a typical 80kWh car battery from solar alone, you need a large system and the flexibility to charge only during peak sun hours. Most people don’t have both.
What about charging at night?
Solar panels generate no power after dark. Evening and overnight charging draws from either the grid or a solar battery – if one is installed.
This is the consideration most clients overlook when planning EV charging with solar. They imagine charging from the sun, but most people plug in when they get home in the evening.
Do You Need a Battery to Charge Your Car From Solar?
If you charge in the evening or overnight, a battery is needed to use stored solar energy. The challenge is scale.
A typical EV battery holds 60–80kWh. A typical solar battery installation is around 10kWh. The gap between those two figures is the honest answer to this question.
The largest battery system I’ve installed to date is 40kWh. But even that wouldn’t fully charge an 80kWh car battery on stored solar electricity overnight.
An 80kWh battery bank could cost up to €30,000-40,000 in lithium storage alone, and it’s not a system I would personally recommend.
What a battery does well is bridge the gap. For EV charging, it allows clients to use stored solar in the early evening before the grid takes over for the remainder of the charge. But again, we’re talking about topping up rather than fully charging.
How Do You Size a Solar System If You’re Planning to Charge an EV?
Two factors drive the sizing: current electricity consumption and charging schedule.
The charging schedule matters because it determines whether a battery is needed. A client who can charge during the day – working from home, for example – needs a different system to one who plugs in every evening.
The starting point is always the electricity bill. You can find the full calculation here – below is a quick overview.
Step 1 — Find your baseline home consumption:
| Step | Calculation | Example |
|---|---|---|
| Highest monthly usage | — | 1,800 kWh |
| Daily usage | 1,800 ÷ 30 | 60 kWh/day |
| Minimum system size | 60 ÷ 6 (peak sun hours) | 10kW |
Step 2 — Add your EV charging load:
| Step | Calculation | Example |
|---|---|---|
| Daily EV charging need | Hours charging × charger kW | 2 hrs × 11kW = 22 kWh/day |
| New daily total | Home usage + EV | 60 + 22 = 82 kWh/day |
| Revised system size | 82 ÷ 6 | ~14kW minimum |
Adding an EV charger in this example increases the minimum system size from 10kW to 14kW. That is a meaningful difference.
Want to Find Out How Many Panels You Need for Your Property in Spain?
I recommend booking a Free Solar Survey with my team at Marblanc Solar.
A Free Solar Survey includes:
- On-site inspection by a qualified electrician or survey engineer
- Drone roof mapping
- Shading, orientation and tilt analysis
- Review of past electricity bills
- Thorough Q&A about your desired future consumption — including EV charging
- Solar proposal using the world’s leading design software
- Itemised quote and financial analysis
It’s free. The total estimated value is €250.
Can’t I Just Use ChatGPT?
I see homeowners use AI to estimate system size all the time. But ChatGPT doesn’t know your roof angle, orientation, or how shading will affect your output. AI is only as good as the information you give it.
For that you need a drone scan and specialist design software. Once you have the accurate data, you can feed it into AI and it will be far more useful to you. The Free Solar Survey gives you that foundation.
