Going Solar for EVs, Part 2

by admin on July 30, 2013

When I got home from work last night, I was happy to see that my MC-4 cable had arrived in the mail! The one thing I was missing from hooking up the solar panel to directly charge an electric vehicle is that fancy little cable.

This morning, I pulled out my assorted pile of parts, including a disconnect box, solar charge controller and a voltmeter. Those were already mounted on a piece of wood, the same way they were when I was experimenting with solar vehicle charging at the MREA.

With my brand-new MC-4 cable in hand, I SNIPPED it in half! Yep! Brand new cable…… and I cut it.

The reason why is that I don’t actually need one cable. I need TWO that are both bare wire at the end. The fancy solar end connectors will plug right into the solar panel, and the cut ends will be threaded down under screws in the disconnect box.

Hooking up the panel to the car was actually pretty straight-forward. The two cut ends went to the disconnect box, and that was wired to the controller. I added a 50 amp Anderson disconnect to the charge controller, and the ammeter was already wired up.

Next, I grabbed my Anderson cable that I made to connect my motorcycle to the UPS for my Poor Man’s Smart Grid. One end plugged into the solar charge controller, and the other plugged in under the seat in the Citicar.

With a flip of the disconnect, I had power flowing from the solar panel, to the charge controller, to the car, and I was charging! The voltmeter shows the state of charge of the battery pack. I’d still like to add an ammeter to show how fast the current is flowing. The maximum current the panel is designed for is 10 amps, so a 0-10A meter would be great. (Anyone got one they want to mail to me?)

Although it was cloudy today, I was still getting charge. In pretty heavy overcast, the panel was still putting out 2 amps at 55 volts, or about 110 watts. And while the panel in full sun is rated for 405 watts, it’s still good to know that I get something out of it even in poorer weather.

So, as a test, it was completely successful! However, the solar panel is still just on a temporary ground mount, and I bet you can tell by looking that the electronics I’m using are NOT sealed against the weather. I’ll have to tidy up the wiring and mount the electronics inside my garage, out of the weather. At this point, my charging cable is a little short as well. It was only designed to reach inside my garage from the UPS to my motorcycle. Right now, I had to drive the Citicar onto the grass to make it reach. Once the electronics are mounted inside the garage, I’ll have plenty of reach with the charging cable.

In the next episode of this project, I need to figure out how to properly mount my panel where the sunlight can reach it. It’s too bad that my yard is rather limited in solar access. One of the few places I get OK sun is right next to my garage, but the panel really needs to be up in the air. That’s also where I want to put a swing-set for my little girl.

Can anyone say solar-powered swing-set? Yep, I’ll start working on it…

Stay Charged Up!

{ 3 comments… read them below or add one }

1 Tim Fulton August 9, 2013 at 1:08 pm

Next time I see you remind me. I have a 0-10A ammeter off my riding mower. 🙂

2 Paul Stallaert September 4, 2021 at 7:14 am

Hi great video,can I put a couple solar panels on my roof of electric BMWi3 car to charge the car as I drive Thanks Paul

3 Ben N September 4, 2021 at 1:05 pm

Commercially-built electric cars are designed so that you can NOT drive while charging. It keeps you from starting the car and driving off and tearing the cable out of the wall, just like what people used to do at gas stations, driving off with the hose still in their car!

Even if you COULD charge while driving, solar that would easily fit on the roof of your car would provide only a small amount of power compared to what it takes to drive the car. Essentially, it just wouldn’t be practical.
If you had a fairly large roof, you COULD charge slowly while parked. That said, if you are already parked, a better place for solar would be the roof of your house or business.

Slower-speed electric vehicles, which spend lots of time out in the sun, and have a nice large flat roof anyways, sometimes do use solar. I have seem both golf carts and electric pontoon boats which make good use of solar on or in place of a roof.

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