Tag Archives: May

May Showers Dominate Solar Production and Electric Vehicle Efficiency is Stable

May was a rainy month in eastern Iowa.  How rainy?  It rained for twice the number of hours in May and three times the usual rainfall hit the ground.  Things were really wet.  Like the “ground is a sopping wet sponge” wet.  It had an impact on May’s solar production:

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Now, just over 542 kWh of clean, green solar electricity is not bad.  It is down about 80 kWh from the same month the prior year.

All in all, my household ended up about 10 kWh ahead of consumption for the month of May including home charging of the Nissan Leaf.  When you can drive all month and live in house with modern amenities all powered by the sun that is considered a win.  Sometimes I just feel like I am living in the future.

For the month I drove 937.4 miles in my Nissan Leaf at an average efficiency of 5.5 miles per kilowatt hour.  This beats my efficiency the prior month by 0.1 miles per kilowatt hour.  This saved ~1,080 pounds of carbon dioxide emissions versus my prior vehicle assuming that I charged using grid electricity, which in Iowa averages about 1 pound of CO2 per kWh.  As noted above, I actually ended the month ahead of my consumption so the emission savings were probably higher.

It does not seem like a big win in terms of efficiency.  However, there are two round trips to Iowa City that totaled almost 140 miles of driving at highway speeds.  For anyone who has driven a Nissan Leaf there is a moment of dread the first time that you get the little car up to 60 miles per hour or more and watch your efficiency drop like a stone in freefall.

The trick is to minimize interstate highway type driving in favor of more sedate state or county highway driving.  That is to say, drive 55 miles per hour as opposed to the 70 miles per hour or more on the interstate.  It takes a little longer, sure, but there is something really peaceful cruising along with the windows down and the silence of an electric vehicle drivetrain.

It also helps to have access to public charging at the midpoint of your trip.  In Iowa City there are ChargePoint facilities available in several public parking ramps.  You pay for parking (first hour is free and a $1 per hour for any additional time) and the charging is free as long as you have a ChargePoint account.  My Leaf is equipped with a standard Level 2 charging port so it can accept, at most, 3.3 kWh of electricity per hour of charge.  It is not a lot for the ninety minutes or so that my errands in Iowa City take, but it provides a margin of safety for the trip home that eases any potential range anxiety.

These trips have gotten me thinking about electric vehicles and range.  Maybe the issue is not absolute range, as in 235 miles of range when fully charged, but rather the ability to gain a lot of range in a short period of time, as in 80% battery charge in 30 minutes.  If I was able to regain more than three quarters of my vehicle’s charge in less time than it takes to make a quick trip into Costco that would change my route calculations considerably.  Also, if more public charging facilities were available at destinations that might also change behavior.

Do I spend a little more time in downtown Iowa City because I am charging my Nissan Leaf?  Probably.  Think about that from an economic development standpoint.

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Over 600 kWh of Solar in May

May was a good month.  My solar system produced over 600 kWh of electricity:

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Coupled with the mild weather I ended the month up approximately 284 kWh for the month and a total of approximately 348 kWh since my system was turned on in August 2017.  I am hopeful that the next couple of months will be big producers.  I am also hopeful that I can keep the air conditioning to a minimum, but it has already been extra hot in May with the Memorial Day weekend being just short of a blast furnace.  Damn you climate change!

I believe that the past several months show that we can move toward a 100% renewable energy future without sacrificing modernity, which is what naysayers would have you believe.  We can cut our energy usage a lot with smart use and efficiency so that the leap to renewable energy only is not so large.  It is a lot easier to produce enough electricity via solar panels for a house that uses 300 to 400 kWh per month versus a house that uses the U.S. average of more than 900 kWh a month.

Now, if I could just cut down on my commuting miles a little bit more…