Solar EV Charging - What You Need to Know

You know how the saying goes, "you can't teach an old dog new tricks"?

Well, it might be true for the most part, but once these tricks become the norm, they won't have a choice but to conform.

This is especially true with solar power.

We're all so used to using non-renewable energy like coal, fossil fuels, and the controversial nuclear energy.

With most of the modern world signing the Paris Agreement, there have been some aggressive measures to counter the effects of climate change, which include reducing carbon emissions to net zero by the mid-21st century.

While industrial factories leave the largest amount of carbon footprint than anything else, reducing carbon emissions on a people-level begins with finding alternatives to gasoline and diesel-powered vehicles.

And electric car manufacturers seem to have it all figured out, so much so that select states in the US, like California, have ordered to phase out internal combustion engine vehicles by 2035.

The technology for electric vehicles has grown by leaps and bounds, considering that it's relatively still in its infancy.

Now, not only can EV owners cut on gas expenses, they can further save on electricity costs by using solar energy.

Solar power still remains the most reliable source of clean energy, and electric cars can reap its benefits too.

Here's how:

What is EV solar charging?

At its simplest, solar EV charging uses solar panels installed where there is ample sunlight.

The solar panel then converts the solar energy into something that can power your electric vehicle.

That's just an easy explanation.

Here's how electric car charging really works with a solar power system.

The solar EV charging process

First, you'll have to install a photovoltaic (PV) solar system, to convert sunlight into electricity.

This PV system is made up of multiple solar cells that typically produce around 1 to 2 watts of power.

These cells are made of thousands of semiconductors less than the thickness of human hair.

They're sandwiched between glass and/or plastic materials to enable them to withstand harsh weather conditions outdoors.

As you can see, PV cells don't produce enough electricity on their own, so they're connected together to form larger units producing electricity, called solar panels or modules.

These can be used individually or connected to one solar installation or another to form a solar array.

Solar arrays are then connected to the electricity grid to produce electricity and complete the solar energy system.

Some EV owners opt to install solar thermal systems instead, which use sunlight to heat air or water.

The produced heat, in turn, is used to eat up the car's battery.

These days, some manufacturers offer solar-powered EV charging stations with a larger PV system, producing enough electricity to power multiple batteries at once.

Solar panels turn photovoltaic cells storing energy from the sun into DC electricity.

This DC power is then converted into AC energy by a solar inverter and is either stored in a power bank or used immediately.

Using a power bank makes sense as solar energy has varying power and the aim is to have a reliable and consistent renewable energy from source.

Home solar EV charging explained

Home solar EV charging involves the use of either a dedicated solar car charger or an ordinary EV charger hooked up to your own solar panels without using additional equipment.

A typical solar EV charging setup includes the following components:

• Solar Panels. Solar panels "harvest" solar light using photovoltaic cells and convert it into DC electricity.

• Solar Inverter. This converts DC power to AC electricity needed to recharge your vehicle. Some inverters have an integrated EV charger, while most Electric Vehicle Supply Equipment (EVSE) have one built-in in their system.

• Electric Vehicle Supply Equipment (EVSE). EVSEs, more commonly referred to as EV chargers, connect electric vehicles to a power source. Its components allow you to safely charge your electric car battery. There are three levels of EVSE charging: Level 1 is the most basic and slowest, providing a standard 120-Volt; Level 2 is capable of 240-Volt charging; and Level 3 is DC fast charging that can provide 480-Volt or more. Level 2 and DC fast chargers are commonly seen in public charging stations.

• Battery Storage System. The solar battery storage system ensures excess solar energy doesn't go to waste. When your EV is disconnected from a solar charger, the system will still store energy. And when you reconnect your EV, it will first spend the energy stored before drawing from the new stock of energy generated by the solar charger.

How to charge an EV at home using solar

If you already have an existing solar system at home, you're in luck, as you're saving some pretty pennies from solar installation costs. Here's how you can use excess energy from your solar energy system to charge your electric car:

1. Check the condition of your existing solar panel installation. Make sure that it can still produce enough electricity to power your EV charger. If not, you might need to upgrade your setup or draw power using a different method.

2. Connect your electric vehicle to the charger with the right charging cable.

3. Press the "Charge" button on the charger or on your dashboard to start the charging process.

4. Monitor the charging status of your electric vehicle. Most solar EV chargers display how much electricity is being generated and how much energy is used to charge your EV.

5. Disconnect the cable from your vehicle once the battery has been fully charged.

EV battery capacity - kilowatt-hours (kWh)

To help you better understand the different types of chargers and charging rates, it's important that you know your EV's battery capacity and range.

Battery capacity refers to how much power is stored by the battery.

It's measured in kilowatt-hours (kWh) and ranges from 24 kWh to more than 100 kWh.

An average electric vehicle will have around 65 kWh of battery storage capacity, which translates to about 217 miles or range, depending on several factors like driving conditions and efficiency.

With every 1 kWh, you can expect around 3 to 5 miles of driving range.

A lighter, more efficient EV uses as little as 12 kWh for a 62-mile drive (1 kWh = 5 miles), while a heavier, high-performance vehicle can use up to 20 kWh or more for the same distance (1 kWh = 3 miles).

On average, EVs use around 16 kWh per 62 miles (1 kWh = 3.7 miles).

Types of home EV chargers

As you all know, there are three levels of EV charging, with the first two being suitable for home charging.

Level 1 is the most basic and slowest of the three, giving you around 3 to 5 miles of range per hour. These often come with your purchase of an EV and can be directly plugged into a standard wall socket.

Level 2 is the ideal home charging station as it can provide around 20 to 30 miles per hour. These can be plugged into the same outlet used by your dryer, but having it hardwired can give you a bit more charging power.

DC fast charging, as the name suggests, uses direct current to charge your electric vehicle or car. It can provide between 50 and 90 miles per hour, giving you 80% of charge in just 20 minutes. Because of the high power requirement, there can only be found in select public charging stations.

The 4 types of home EV chargers

1. Portable plug-in. These Level 1 chargers plug into a 10A wall socket, which takes 24 to 36 hours to fully charge your EV battery. These draw around 1.7kW to 2.0kW, translating into 6 to 9 miles per hour. 15A plug-ins are also available but require a dedicated socket.

2. Single-phase wallbox. These Level 2 chargers can either be wall or post-mounted with a rating of 32A, equivalent to 7.4kW of power. These can supply between 25 to 31 miles of range per hour, fully charging an EV in 8 to 10 hours.

3. Three-phase wallbox. These Leve 2 chargers look similar to single-phase chargers but can provide three times its power. These can draw up to 22 kW, translating to around 75 to 93 miles per hour.

4. Combined solar inverter and EV chargers. As the name suggests, these chargers can charge directly from your solar energy system, eliminating the need for a separate EV charger and any upgrades to your system. These must be installed in a garage or somewhere close to the vehicle.

Benefits of solar EV charging

1. Low cost. The upfront installation costs may be expensive, but the long-term savings from constantly rising fuel and electricity prices make up for it. Installing solar was found to be cheaper than buying grid power. Pairing solar panels with electric cars is an effective solution to save money.

2. Tax incentives. Owning an electric car and installing both a home charging station and residential solar panels to charge your vehicle has tax incentives in most US states.

3. Peak season benefits. During the hotter months when electricity demand is high, customers pay a higher fee than during the off-season. Instead of grid charging, solar EV charging makes sense as there is much more high-quality sunlight during the summer season, which means your solar panels can generate electricity at a faster pace.

4. Sustainability. Solar power is one of the cleanest and most reliable sources of energy. With most still relying on fossil fuels, switching to green energy can lessen the environmental impact.

FAQs

Can you charge an EV with solar?

Yes, you can charge an EV with solar. Solar chargers generate AC power that can charge your EV battery.

How many solar panels does it take to charge an EV?

It will take around 5 to 12 solar panels to efficiently charge an EV. To know exactly how many solar panels your EV will need, you'll have to do some computation. First, find out how many kWh a panel can produce by multiplying the hours of daylight per day (usually 4.5) by the panel's wattage. The wattage can range from 250-400 watts. Divide the wattage by 1,000 to get kWh. This is the daily output of a single solar panel.

We know an average EV needs around 16 kWh of electricity per day for a 62-mile drive. Divide this by the daily output of each panel to get the number of panels needed to charge.

Let's put that into perspective using a 360-watt panel as a reference:

Step 1: 4.5 hours of sunlight x 360 W = 1,620 W per day

Step 2: 1,620 W/1,000 W = 1.62 kWh per day

Step 3: 16 kWh/1.62 kWh = 9.87 panels or 10 panels