Sunday, November 11, 2012

Sunshine go away today, I don't feel much like dancing

Wait, what?

No offense to Jonathan Edwards (either of them - the singer-songwriter, or the CT based winemaker of the same name whose winery I spend a little too much of my free time in).  Although I'm pretty sure the winemaker doesn't want the sun to go away any more than I do.  Why do I want the sun to keep on shining?  Two reasons.  Sunshine was an anti-war song that still 'plays' well today.  Today, however, many of our wars are oil based.  My solar array has finally been installed, approved and is now live (Shhhh! Don't tell my installer.  I flipped the switch after I noticed CL&P swapped out my old meter with a net meter).  This means that I am no longer a liar, and that I am now driving without a single dollar going to big oil (at least on our primary vehicle).

Although we signed a contract for a 17 panel SunPower SPR-240E array with inverters in each panel, it didn't play out as hoped.  This was due to the complexity of the roof on our 110+ year old home.  Because of wind speed where we live and the height of our roof, the setback for the panels from the edge of our roof ended up larger than we had hoped.  As a result, we had to reduce our array size to a mere 12 panels to keep the panels far enough away from the edge.   This resulted in a 2.88 kW system that will likely generate ~3200 kWh each year here in southern New England.  Perhaps I should have just installed a Vertical Access Wind Turbine like the one Jay Leno put on his garage...  

SunPower PV Array
With the average American home using 11,496 kWh each year, you might wonder what's the point of installing a PV system that only generates 3200 kWh per year.  We're not what you would call average as we're using a bit less than average currently - 8000-8500 kWh is the range we've been in for the past 6 years.  More importantly, however, is the ActiveE.  Even thought the ActiveE is a load, we're still averaging 3.5 miles/kWh.  Ooooh - 3.5 miles/kWh, big deal.  Why is that important related to a solar array install?  There have been plenty of attempts to explain cost per mile of an EV, but every one of them that I've read breaks it down by cost to drive a certain number of miles.  I'd like to try a something a little different here.

Correcting for charging losses, those 3200 kWh/year will power our ActiveE ~10000 miles.  After a little over seven months and 7300 electric miles driven with it we are right on track for 12,000 miles per year.  So our system generates a shade over 83% of the energy we need to power our annual driving habits.  And to be honest, if we had the roof space, we would have built a large enough system to completely offset our annual mileage.  That would have cost us $11900 after all rebates.  So here's the question - would you be willing to spend $11900 today to never have to pay for gas again?  Think about that - if your current car gets 20 mpg, paying $11900 is like prepaying 5 years worth of gas (at today's gas prices) for the benefit of never having to pay for it again - and that's with an inefficient ActiveE.  The BMW i3 is expected to yield an estimated 5 miles/kWh.  The system size necessary to power it 12000 miles in southern New England is only $8350 (or 3.5 years of pre-paid fuel costs). 

The fact is, now even more than most people, I want the sun to shine constantly and watching the meter on my array when the sun is shining makes me feel like dancing.  Sorry Jonathan...

P.S. - I've always enjoyed 'Sunshine'.  Its just that it played so well as an antithesis for this topic that I had to use it in the title.  Having said that, here's my real plug for both JE's.  If you've never experienced it, I highly recommend Jonathan Edwards singing at the [other] Jonathan Edwards Winery.  He plays there almost every summer.  Great wine & great music - almost as good as free electricity from the sun and an EV...

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