It seems like a perfect combination: solar power and electric vehicles (EVs). Simply set up some charging stations that are powered by solar panels, and the EV driver can enjoy an emissions-free recharge. After all, solar costs are decreasing, and EVs are gaining in popularity, so why not combine the two?
Several charging station providers and solar companies say it is indeed possible to have solar supply at least some of the electricity to power plug-in vehicles, but there are a number of hurdles to a wide rollout of solar-powered EV charging stations.
‘It's a perfect matchup when you consider all the developments with battery storage and you consider where PV is going as those costs come down and the performances go up,’ says Robert P. Boisvert, executive vice president of GOe3 LLC.
Scottsdale, Ariz.-based GOe3 is building a network of EV charging stations on interstate highways. The focus is on connecting cities and eliminating owners' range anxiety – the fear of not being able to reach a charging station before the batteries run dry.
‘EV drivers are charging at home 70 percent of the time,’ Boisvert says. ‘The real need is on interstates. You are not going to care if there is a charging station two blocks from your house.’
Not every EV site is suitable for solar. The company has plans to build 1,000 charging stations over the next five years. Of these, 10% of them might be solar.
‘Each site requires its own analysis,’ Boisvert says. ‘It depends on the location, how much sun they get, peak demand charges. Most of what we focus on are sites that have relatively high power requirements, so solar makes sense.’
The interstate locations will likely be travel center locations or places of interest. The chargers will be DC fast-charging stations, as opposed to the Level 2 stations that take longer. The DC fast-charging stations would not need separate inverters.
‘Instead of having to buy another inverter for solar arrays, we can use the one inherent in our charging stations,’ he explains.
So far, GOe3 has built seven charging stations. None are solar, but solar might be in the works for a planned location in Arizona.
Solar can make sense in some charging stations in the future, says Josh Castonguay, director of generation and innovation for Green Mountain Power in Vermont. ‘I think you will definitely see charging incorporated with solar, no question, in certain locations,’ he says.
The more ambitious your solar EV charging requirements are, the more space will be needed.
‘If you're trying to cover a little bit of charging, you need a few panels,’ Castonguay says. ‘If you want to cover all your charging, you would need to include batteries, as well – for at night – or limit the charging only to solar hours.’
Also, the space would have to be a good solar site – one that is not shaded. One complication is that EV chargers are often near commercial buildings, which cast long shadows. Nevertheless, there could be opportunities for combining solar and EV charging. Providing solar EV charging during peak demand hours could take a lot of pressure off the grid.
Green Mountain Power recently announced a partnership with NRG EVgo to build 12 Freedom Stations in Vermont. The first one opened in Rutland, Vt., this year. The station can provide approximately 80% of a battery charge in 25 minutes when using the DC fast-charging option. The Freedom Chargers will also have Level 2 capabilities that provide up to 24 miles of charge per hour.
So far, these are not solar, but that could happen in the future, Castonguay says. ‘Ideally, we will see locations with rooftop solar installing a charger, as well, along with an energy storage capability,’ he says.
In San Diego, Envision Solar announced in August that it agreed to a partnership with ChargePoint, which operates an EV charging network in the U.S. and Canada. Both companies will offer ChargePoint chargers on Envision Solar's solar-powered EV charging products. The partners say the combination will enable EV owners to drive on sunshine.
Nora Caley is a freelance writer based in Denver.