If you could drive a solar-powered car, would you?
We live mostly off-grid and primarily use solar power to run our RV. When we started talking about getting a second vehicle, it made perfect sense to us that it would be a plug-in hybrid electric vehicle that could take advantage of our RV’s solar system.
Not only would it be a solar-powered car when using electricity, charging the car on solar would make sure we maximized the potential of our solar system! So, we did it.
The Chevy Volt Plug-In Hybrid
Our secondary vehicle for RVing is a Chevy Volt.
This is one of the most unique cars on the road (from my perspective as an engineer). Its unique because its both an electric car and a gas car all in one.
Now, I know what your thinking – “that’s not unique, there are hybrids everywhere!”
Yes, that’s true, but this is special hybrid because its internal drivetrain is in series instead of parallel. What this means is that the car is primarily an electric vehicle, and the gas engine is just an electrical generator.
In parallel hybrids, (pretty much all other hybrid cars out there) the gas engine is the primary driving force and a secondary electric motor assists (and can sometimes drive the car in limited situations). The series hybrid design gives us all the features of an electric car, plus the extended range of a gas one.
The electric side is what enables us to turn it into a solar-powered car!
Driving Our Solar-Powered Car
Our car can go 40-50 miles on an electric charge before it switches over to the gasoline engine that provides power for an extended range. When on electric power the car is silent and smooth with fast acceleration.
On gas it’s… well pretty much the same.
Because the gas engine is just a generator that charges the battery and flows power to the electric motor the driving experience does not change except for the engine noise. The weirdest part about driving this car on gas is that the engine speed is not directly reflected by the car speed. Step on it to get on the highway and the car will go, but the engine might not rev up until you are up to speed.
How We Charge Our Solar-Powered Car
The gasoline engine is basically a generator, so it can charge the cars battery if needed. But its primarily designed to be charged from an outside electric source. Electric cars can charge from any power source that meets their requirements, and in our case we plug it into our RV.
We built an extensive solar system on our RV including a large bank of Battle Born Batteries so that our RV is like a little mini power generator and grid. This enables us to plug the car’s portable EVSE (electric vehicle charge equipment) directly into an outlet on the RV and charge the car!
Now, in normal conditions the car takes anywhere from 8-12 hours to charge from a fully depleted battery and can consume about 11Kwh of energy. Since we are not plugging into an unlimited source of energy, we do need to consider a few things to get this to work properly with our RV’s power system.
Optimizing the RV’s Solar System with a Solar-Powered Car
Sometimes, we just plug the car charger into any old plug on the RV and that works great. However, that means there is no automatic shut-off to stop the car charging. The problem with this is that if the sun goes down or the day clouds up the car will start drawing down our RV’s batteries.
This is OK to a point, but if we don’t get enough sun we won’t have enough power to do other things in the RV.
The Programmable Plug
We added a new circuit dedicated to charging the car to address this issue. This circuit comes off a secondary AC output that is available from our RV’s inverter (this is the device that converts the RV’s battery power to AC power like in your home). This circuit is programmable and we can set the limits of when we want the car to charge or not.
We decided to control the cars charge based on the RV’s battery state of charge.
We programmed the system so that if the RV’s batteries get above 85% charged from the solar energy, we turn on the car’s circuit and start dumping the solar power to the car. If it’s a sunny day, we make excess power even with the car plugged in and the RV’s batteries continue to climb.
Should the day end or get cloudy, the RV’s batteries will drop. When they hit 80%, the car stops charging. This gives us a reserve capacity of energy to use in the RV.
Below is the schematic of our RV with the car show. Read all about it on our post about our Ultimate Off-Grid RV Solar System.
What if the car doesn’t get charged?
If the car doesn’t get charged, it doesn’t matter. That’s the beauty of the plug in hybrid. The car is fully usable as a gas powered car that still gets pretty good fuel economy (40-50MPG).
What about long distance drives?
For long distance drives, we change the programming of the system. When we are driving, we don’t use as much power. We dump 80% of the RV’s battery capacity to the car instead of the usual 20%. This allows the car to drain the RV’s batteries down to 20%. The RV recharges while drive when we aren’t using any ancillary electricity.
When we get to our overnight spot we plug the car in and let it draw down the RV’s energy. We know we won’t need much for the next day of driving.
We also plug the car in at rest stops when taking a slightly longer brake (i.e. for lunch). This only adds a few miles, but every bit adds up. Usually, about 10% of our long-distance driving is supplemented by solar (if the sun is shining, that is).
Does this RV solar-powered car thing work?
Yes, it does work!
While the solar power we put into the car is not enough to power all of our driving needs (namely the long-distance) but it supplements our energy significantly. Most importantly, it uses all the power that otherwise would be lost from our solar system.
Once the RV’s batteries are fully charged from the solar energy, that excess power would go unused. With this system, we have been able to use that extra power to increase our overall fuel economy. Almost 100% of our driving over the summer was solar-powered.
Over the entire summer (3 months) in one location we only burned 1 gallon of gas!
Watch The Video:
See it in action over on our YouTube channel!
Are Solar-Powered Cars the Future?
We sure hope so! Having even a little bit of our driving supplemented by the sun has been amazing.
However, there is a lot to consider in trying to power a car full-time from the sun. It is completely possible to charge an electric only-car like a Tesla from off-grid solar, but the up-front cost is still prohibitive for most. As the cost of solar and electric cars continues to plummet, we fully expect to see this become a more viable option.
If you want to see someone who has done it already, check out Jason Hughes’ crazy system!
We are going to continue to test our Ultimate RV Solar System, dive deeper into off-grid power, and share our findings on video and this blog.
Let us know what you think in the comments below! How else could we power this car? What questions do you have?
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