Peter's Solar Electric Van · 4 October 05
Here’s a conversion project for all of you folks who have been asking about putting solar panels on an EV.
Peter took it one step further and put a wind generator on the EV as well. Now, before your mind gets whirling too fast we need to clarify that he only uses the wind generator when parked. No perpetual energy in the UK either.
- Thundersky Lithium batteries (30 of them! nice present from Dad)
- Curtis controller
- Advanced DC motor
- Solara Solar Panels
- Air-X wind gen (I put one of these on my Mom’s house…great!)
- Homemade Battery Management System (BMS)
I think the Toshiba laptop embedded in the dash is the crowning touch.
That’s a view of the BMS (battery management system, a requirement for the lithium battery pack) which Peter designed and built himself. He was also good enough to make the whole design available for anyone to download, visit the BMS page.
The download includes a well written pdf covering the BMS, EV electronics, and even the laptop and basic monitoring system it runs.
If you are in the Asenby, Thirsk or Northallerton area in North Yorkshire he invites you to stop by (after a courtesy email, of course) to see his creation.
Update: I thought I ought to post an update regarding the wind/sun power. In another article I mention that it doesn’t seem worthwhile to put solar cells on a vehicle. It is hard to get optimal alignment with the sun and you end up carrying the panels wherever you go, which adds weight and in some cases increases drag.
Peter shows up to 200 watts from the solar panels and 400 watts from the wind generator, with a combined maximum output of 600 watts. In order to get that, though, he needs direct sun (overhead) and 28mph winds. If you check out the specs for the Air-X (pdf) you’ll see that the power curve falls pretty dramatically, with less than 100 watts when you get down below 20mph winds.
I have wind measurement gear on top of our house (12’ above roofline) and it averages about 5-8mph during the day with peak gusts to 15mph. This time of year the sun is lower and lower on the horizon so a roof mounted solar panel would be less and less efficient at gathering power. Seems to me that on a good day, with sun and wind optimal, we might get 300 watts total. An average day might work out to less than 200watts.
When I ran numbers for Eve’s performance it came up with a watts per mile of 230. That means a daily commute of 8+ miles is around 2,000watts. So an optimal wind/sun day would take six hours to reclaim the power, assuming I reclaimed half while at work and had enough wind/sun to reclaim the other half when I got home. An average day would take 10 hours or more.
Lots of optimism in this calculation: the wind and sun are expected to stay constant over the entire period, perfect efficiency for the transfer of sun/wind power (converting to high enough voltages to charge the batteries), and we aren’t taking into account the weight added to the EV. The wind gen is 13lbs, pipe probably as much or more, solar panels, mounting hardware, and electronics probably brings it all up to at least an extra 100lbs being hauled around.
I don’t bring all of this up to take away from the work Peter has done. I just wanted to point out things you should consider when undertaking such a design. It’s a great proof of concept and an interesting experiment into alternate methods of powering an EV.
Peter has been upgrading his EV to an AC drive system and we’ve posted an update: Peter’s Solar Electric Van II.