Going Solar for EVs and more!

by Ben N on July 26, 2013

About a month ago, I was at the MREA – the Midwest Renewable Energy Association Fair – where I was showing off my electric motorcycle and giving presentations of DIY Clean Transportation. But probably my favorite thing of that weekend was my cobbled together Vehicle to Grid display!

Ahead of time, I had talked to somebody at Helios Solar Works, who was going to be at the Fair, and arranged to borrow one of their 48V solar panels while there. I rigged up the panel through a basic fuse box/disconnect to a solar charge controller and the UPS (from my Poor-Man’s Smart Grid) and then to my electric motorcycle.┬áIt worked GREAT! All weekend, I had a fully-charged electric motorcycle (which I used to get to and from the campground) which could also supply AC wall power!

I ran through a little quick math in my head. The panel makes 400 watts, and is designed for charging a 48V system, so that’s basically 8 amps of charging. The motorcycle has four 55AH batteries. Divide that 55 amp-hours by 8 charging amps, and you get just under 7 hours. And that would be for a fully discharged battery. Assuming that a person doesn’t try to kill their battery on every trip, and even accounting for charging inefficiencies, that STILL means a FULL charge from solar in eight hours!

A few days ago, I visited a friend of my parents, who is a DIY Off-Grid kind of a guy, and was impressed with his solar setup, both photovoltaic AND solar hot water. He had some older 50 watt PV panels for sale, eight of them, which comes to, you guessed it, 400 watts. Of course he also wanted a little more money for them than I thought they were worth….. And I wasn’t even sure exactly how much NEW panels cost anyways.

So, I checked some web pages for rough prices, and then called Helios to see if they had any B-stock panels available. Sure enough, they did, and while B-stock doesn’t come in a box, and might have a scratch in the aluminum frame, it’s also only 90 cents per watt! So I placed an order for a 405 watt B-stock panel, and drove to Milwaukee the next day to pick it up.

The Helios building is clean and modern, with a simple layout, nd office area in front, and an assembly plant in back. It was daylight-lit (with “SolarTubes”) and had a combination of machines and humans assembling solar panels. I was quickly helped with loading the panel into the back of my pickup and then got to take a quick little tour. Pretty neat to see the robo-solderer connecting one PV cell to the next! Cells are assembled, soldered, sealed, baked, framed, and tested right there.

Once back home, I pulled the panel out of the back of the truck, but I’m still not sure of the best place to put it. Unfortunately, I have fairly poor solar access at my house. I decided that I would simply ground-mount it for the moment, until I can spend a little more time doing it right. I found three pieces of aluminum C-channel in my garage, and bolted them to the back of the panel frame. Then I set the panel on the ground, with stakes propping up into the mounts.

Rob Frosts garden and swing

What I’m really thinking about doing right now is a “Solar Club House”.
We have a swing in the back yard for the two-year-old, but it’s on the only tree branch that’s at all usable for a swing. Even then, it’s not a very good branch! So, I was thinking about building a club-house swing-set from 4×4 posts. You know what I’m talking about, it’s made from wood and has a ladder and slide and a place for a swing. The upstairs is usually covered by a peaked roof made of canvas. Only in this case, the south-facing roof would instead be a 400 watt SOLAR PANEL! (The one shown here belongs to my permaculture buddy, Rob.)

From there, I could run the power to the garage to recharge the ELECTRIC MOTORCYCLE or the CITICAR. The charge controller I’m using even supports a DIVERSION mode, where when done charging, power simply gets switched to some other output. I’d love to use that and hook it up to a grid-tie inverter. Then what would happen is that the electric vehicle would get charging priority, but when fully charged, the “spare” solar energy would go to my house or back to the grid!

At this point however, I can’t even hook up the panel! The simple reason why is that PV panels use special fancy connectors. The current style is known as “MC-4″. Without one of those cables, I can’t plug the panel into ANYTHING. And as tempted as I was to simply cut off those connections and hardwire it to a disconnect box, I’m trying to be patient, and do things “The Right Way.” So, I mail ordered a short MC-4 cable, which I can cut in half and use the two ends to PROPERLY connect the panel up.

In the near future, look for me building a solar club house. Hmmmm, maybe I can find one cheap on Craigslist that somebody just needs moved?

Take care, and stay charged up!

-Ben

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