Saturday, October 8, 2011

Power Savings and Prepping for an EV

Last week, I had some free time to reassess what devices I have running and whether or not I still use them at all. This was born out of some preliminary research into purchasing an electric vehicle (EV). Nissan Leafs are actually available now to those without reservations. That's the more realistic choice, but I really like the Telsa Model S. I've been missing a sporty car since my Honda roadster was totaled last year.

Taking the Nissan Leaf as an example, with its 24 kWH battery and 100 mile range and my current commute of about 30 miles roundtrip, I could drive 3 days per full charge. I would drive one of our other cars one day a week, so that would leave about 16 days/month on the EV. Rounding it to 15 days, I'd need 5 full charges or an additional 5*24kWH = 120 kWH of electricity per month.

Fortunately, we had solar panels installed 18 months ago. Since then, we've been able to stay in the lower 2 tiers of electricity costs for 11 out of the first 12 months we've had them. Those lower tiers are now 12.2 cents/kWH and 13.9 cents/kWH. The 3rd tier jumps to over 30 cents/kWH and the 4th and 5th tiers more costly. In December 2010, we used 73 kWH of tier 3 electricity. The 2nd worst month was January 2011, but we were 60 kWH below tier 3. The other 10 months we were 150-500 kWH below tier 3.

So if nothing changes, it would be "expensive" to drive an EV in December. The 120 kWH of electricity to charge the EV would all come in tier 3 at a cost of about $36 for 450 miles. That ends up being more than the $33 it would cost to drive our Prius the same distance (assuming $3.70/gallon for gas), but less than the $70 it costs our Subaru. It would cost about $26 in January. April to October would be all tier 1 electricity and cost about $14.50. February, March and November would be about half tier 1 and half tier 2, or about a buck more per month than April-October.

These are hardly savings compared to a hybrid - maybe $150/year. Compared to our non-hybrid, it's more significant - $550/year. When the economy improves, those savings will go up as gas prices will rise. For me, the real savings will be not sending as much of our hard earned money to big oil companies or countries that want to destroy the American lifestyle.

Political statements out of the way, there are some special options our electric utility has for EV owners. One is a time-of-use option where they charge a high rate during peak periods and less during the late night-early morning. This wouldn't work out well for us because of all the HA related servers, electronics, etc running 24x7. Another option is the installation of a 2nd electric meter specifically for charging the EV, but that's at least $2000. A third option would be to install an additional 6 solar panels on the west facing portion of our roof. It's not an optimal position and I haven't priced it out - but I figure it would be around $4000. I could do some of the work myself as I did an install with SunWork before. Of course, the obvious option is to cut our electricity usage - specifically the things that run 24x7.

I have to admit, having solar, I've been lazy about conserving. Rather than run a long Cat-5 cable, I plug in another Ethernet switch. Instead of using an extension cord to get to a UPS already installed, I add another UPS. When security cameras get updated, I keep the old ones plugged in pointing somewhere else - not really someplace necessary. Last weekend, I fixed all that. I pulled 4 UPS's, 4 Ethernet switches, 2 cameras, 3 modulators, one Squeezebox and 1 Slingbox. I disabled Connect24 on our Wii so it can idle at 1W instead of 9W. I unplugged a clock radio in the garage that used 10W. The end result is I cut about 3 kWH/day or 90 kWH/month. That's almost as much as the 120 kWH/month an EV would require!! This was by far the cheapest option. You can really see the results in a chart. In the 5 full days since my unplug-fest, our usage has never exceeded 20 kWH/day.


Now, we have headroom for an EV - I just need to decide whether I'm ready to plunk down all the cash for one.

No comments:

Post a Comment