Think The Solar Canopy Is Powering EV Fast Chargers? Think Again.

Fast chargers require so much electricity it would take many more solar panels to power one of them.
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Photo: EVgo
Screen Shot 2021-02-24 at 3
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Recently, a user on r/ElectricVehicles posted photos of an Electrify America fast charging station with a roof over the chargers made of solar panels, called a solar canopy. The comments were overwhelmingly enthusiastic, wondering why all EV chargers don’t have solar canopies that both shield vehicles from the elements and provide electricity to power the chargers. A true win-win situation, right?

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Yes, solar canopies are good. They create some renewable energy where there was none before and they make charging stations more pleasant to use. But it is also important to recognize they do not, by themselves, make charging stations green, or come even remotely close. If we don’t rapidly educate electric vehicle owners on how much electricity fast chargers use and how it compares to other electricity uses they’re more familiar with, we risk solar canopies being little more than green energy theater.

One of the greatest blind spots I come across regarding EVs is most people do not know the sheer amount of electricity required to power just one direct current fast charger (DCFC), the kind that most people imagine will replace gas pumps for the quick fill-up while on long drives. This is a byproduct of most people not having any real reason to understand electric units of measurement. But if more people did understand them, they might intuitively grasp that not only is a solar canopy insignificant to the power demands of a fast charging station, but that reliance on fast charging will make a rapid conversion to renewable energy that much harder.

Most new DCFCs these days can charge at speeds of either 150 kilowatts or 350 kilowatts. According to a study by fast charging company EVGo, under standard use, a bank of four chargers requires as much power as that needed to power 100 and 230 homes, respectively. In other words, just four of these chargers have the energy demand of an entire housing subdivision. Compare that to a typical solar panel, which under ideal conditions can generate about 320 watts, according to solar company Sunrun. In order to power a single 150 kilowatt fast charger, a company like Electrify America would need to install 469 solar panels. A single 350 kilowatt charger would require 1,094 solar panels under ideal conditions covering about 20,000 square feet. And that’s just for one charger. Most charging stations with solar canopies have a dozen or so fast chargers requiring several megawatts of electricity when in use. Solar company Oya says a 5 megawatt solar farm requires some 30 to 40 acres.

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I asked both Electrify America and EVgo, the two largest US fast charging companies, about their approaches to solar canopies over charging stations. And they each have different strategies.

Sourav Das, a spokesperson for EVGo, told me most EVgo stations don’t have solar canopies because of this meager electricity draw compared to the station needs. 

“Most of EVgo’s stations do not have solar canopies or renewable energy installations on site,” Das said. “In fact, it would take acres of solar and wind to power our fast-charging stations (especially our new 350 kW stations), which would be difficult in the retail parking lots and urban centers where we install chargers.” 

Instead of trying to make the station sites themselves greener, EVgo purchases renewable energy certificates, which it claims are “different than buying offsets of carbon because we can actually match the kWh used with the kWh we purchase, which provides financing for renewable energy projects such as wind and solar.” Like carbon offset markets, these projects require third party verification by self-certifying firms. Still, Das insisted “By purchasing RECs, we have a much bigger impact than installing distributed energy on site in each parking lot.”

Which is exactly what EVgo’s biggest competitor, Electrify America, is doing. Spokesperson Mike Moran also acknowledged that “the solar power alone will not provide the necessary energy to power these powerful chargers” but said EA is more bullish on installing solar canopies than EVgo and combining them with battery energy storage systems (BESS), which stores energy when energy is cheaper and releases it when energy is more expensive. This is both better for the environment (cheaper energy typically coincides with higher rates of wind and solar energy) and saves EA money. But it is expensive to install and still relies on the energy mix of the grid from which it draws. Moran said EA has BESS at more than 140 DCFC stations. 

While BESS would help make solar canopies slightly more useful in instances where, say, the chargers sit unused during long, bright, sunny days for long periods and then someone shows up to charge at night, it doesn’t change the fundamental math that a solar array of even 100 panels would, under ideal conditions, need to charge the battery for 10 hours to get one hour’s worth of electricity out of a 350 kilowatt charger. These are rounding errors, and while the solar canopy may look nice and provide some decent shade, it is not helping that fast charger be any cleaner.

Again, none of this is to say solar canopies are bad. They are a net positive, all things considered, because we need all the solar we can possibly get if we want green energy any time soon. But the relationship between EVs and that green energy is more complicated than is often presented. As a recent study argues, more than half of the emission-reduction impact from fewer gas-powered vehicles will be offset by increased emissions from the electricity sector “without significant and concurrent changes to the electricity sector far more substantial than those over the last decade.” It’s vitally important we not mistake those solar canopies as anything like a closed, self-sustaining system, or else the promise of EVs to drastically reduce emissions will remain just that.