Tag Archives: kilowatt hour

A Great Month for Solar Production, Electricity Consumption, and EV Efficiency

At last!  In August 2019 my solar photovoltaic array produced more than the same month in prior years.  I was somewhat consigned to a reality where my best days of solar production were behind me, but August came to the rescue:

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All in, my household ended up 179 kWh “up” in terms of electricity production minus consumption.  Remember, this includes all of my EV miles as well.  For the year I am creeping back toward being even in terms of production minus consumption after some awful months in the dead of winter.  During that period of time my solar array was covered in nearly a foot of wind driven snow and our electricity usage was high due to crazy low temperatures.  Normally August is a heavy month for air conditioning use.  Our HVAC system has been idle since the first week of month.

For the month of August my total miles driven in the Nissan Leaf was depressed by not being home for a little more than a week.  In the end I drove 531.2 miles at an average efficiency of 6 miles per kWh.  Compared to my truck and assuming power is drawn from the electricity grid, I saved ~620 pounds of carbon dioxide from entering the atmosphere.

Since bringing the Nissan Leaf home I have driven a total of 5,138 miles and save 5,854 pounds of carbon dioxide from being released.  Using the most conservative method of calculating savings—which assumes all electricity comes from the grid as opposed to my solar panels—I have saved just under $727 in fuel costs alone.

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Knocking it Out of the Park with EV Efficiency…Solar Not So Much

There are times when driving my second hand Nissan Leaf feels like I am working on cracking a code.  Change one behavior (e.g. turning on the heat) and relative efficiency takes a nose dive.  Adjust a few things (e.g. make sure to drive with the car set in “B” mode) and it seems like you can do no wrong.  Ambient air temperature, type of driving, route choice…on and on it goes.

I am certain that it is the same for a traditional ICE vehicle or even a Tesla, but when you are limited to a little more than 100 miles on a full charge there is a hyper heightened awareness to how quickly the “guess o’ meter” depletes.  However, it was a lot less of a concern this month as I averaged 6.1 miles per kWh for just a tenth of a mile over 900 miles.  That works out to a little less than 148 kWh of electricity consumed and ~1,053 pounds of carbon dioxide emissions avoided versus driving my truck.

Since January I have driven 4,607 EV miles at an average efficiency of 5.1 miles per kWh.  This correlates to ~5,234 pounds of carbon dioxide emissions avoided versus driving my truck.  As I have said before this assumes that I draw all of my power from the grid as opposed to generating it on site with my solar panels.  Based on gasoline prices I have saved about $650 just in fuel since January.

Speaking of solar photovoltaic production, July was a fairly good month:

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720 kWh for the month is good.  It is a little bit less than the same month during the prior year, but I would say that it is within the margin of error.  It is not like this is January and February where snow covered my panels up to a foot deep some times.

All in my household consumption ended up about 26 kWh more than my production.  Included in my household consumption numbers are almost all of my EV charging, so without the Nissan Leaf in the garage we would have ended up over 100 kWh.  Granted, that would mean I was spewing carbon dioxide from the tailpipe of my truck.  I will take the trade.

Unlike some summer months we were home for every weekend and took no trips.  Furthermore, for the entire month of July we went out to eat once.  I feel fairly good about making all but one meal at home, charging my electric car, running the air conditioning when it got really hot, and still managing to almost be even in terms of household electricity consumption versus solar electricity production.  It is my hope that in the next month I will adding about 60% more solar photovoltaic capacity to my roof.

June 2019 Solar was Back on Track and EV Miles were Extra Efficient

June was a better month for solar production:

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Over the course of the entire month my household ended up ~150 kWh (consumption minus production), including all of my EV charging for that same period as I did not use any public chargers.  With at least eight more panels being installed on my roof this summer I am going to be seeing a lot more months with excess production.  Every kilowatt hour that I produce from my solar array is like a nail in the coffin for coal.

The excess production in June was a little artificial because we were on the road for more than a week.  With no air conditioning running it is to be expected that we would run a surplus.  June was also fairly cool with a corresponding lack of need to deploy air conditioning.  The last few days of the month were a reminder that summer in Iowa is a hot and sticky affair.  I am talking temperatures exceeding 90 degrees and humidity levels exceeding 90%.  If there was ever a time where I did not want to come home from the mountains this was that time.

For June I drove my Nissan Leaf a total of ~555 miles at an average efficiency of 5.9 miles per kWh.  This is my best number by far, in terms of efficiency, and makes me wonder if I can nurse my way to a figure over 6 miles per kWh in July.  For the period I saved ~646 pounds of C02 being emitted assuming that my charging came via the grid at an average carbon intensity.

You may ask how I can be ahead in terms of energy production yet still account for some level of carbon intensity for my electric vehicle.  Unfortunately, my photovoltaic array’s production occurs when I am not charging my EV which usually happens at night.  Therefore, to run my Nissan Leaf I am utilizing grid electricity.  It’s a little like keeping two sets of books for the same business.

Solar Power was Nearly Even Stevens in September 2018

Image-1 (3)September was an odd month.  Solar production really fell off because the weather turned overcast and rainy real quick, but the first week or so of the month was really hot and humid.  Here is what the production looked like for the month.

It’s pretty obvious that things were a little gray since the array ended up about 100 kWh down compared with the prior year.

All in, my household ended the month with a surplus of 17 kWh.  The system will probably run a surplus in October and November depending on the weather and, therefore, the amount of heating we deploy before going into deficit for the deep winter months.

With a little more than a year under my belt of solar powered bliss I am pleasantly surprised that my little system—just 16 290 watt panels for a total of 4.64 kW of solar potential—has been able to cover more than my household’s needs.  As I look out at houses in my development and others nearby I wonder how much potential there is for everyone to be solar powered.

Imagine a world where we lived off the power we could produce from our roofs?  That is a future I want to live in.

A Mixed Bag for Solar Production in August

The solar photovoltaic system on my roof had a mixed record of production in August:

Solar August

I would have thought the system would come in a little closer to July’s number, but a consistently rainy and dreary end to the month dashed those hopes.  Still, over 563 kWh of clean solar energy was more than enough to offset my consumption and I ended the month up a little over 100 kWh.  In total, over the course of the past year or so since my system was installed I am up over 800 to 850 kWh.

It’s a little hard to tell exactly where I am at because my utility company replaced my electric meter without telling me so I lost some data points that I was tracking manually on a spreadsheet.  If you have a solar system watch your electric bills like a hawk.  My utility company consistently uses incorrect meter readings that discount the amount of solar electricity that I produce.  It is amazing that my consumption from the grid is never discounted.

My hope is that September turns into a good month for solar production, but the rainy weather that ended August is carrying over in September.  The first few days of the month have been little more than rain.  So much so that the ground is like a wet sponge and my grass is growing like crazy.  Maybe a I should just get a goat to mow the lawn…

Over 700 kWh of Solar Electricity in July

July 2018 was the best month ever for my house’s solar photovoltaic array:

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Approximately 742 kWh of renewable energy from the roof of my garage seems like magic.  I still think there is some black magic going on in those panels that turns sunlight into electricity, but I also still like Harry Potter so maybe magic is my thing.

Even with some days of fairly heavy air conditioning use when the humidity climbed along with the temperature, I still managed to produce ~250 kWh more this month than I consumed.  In total, since my system was turned on at the end of August I am up over 700 kWh when I compare production versus consumption.

Here’s the thing, with a middling sized solar array—just 4.64 kW on a 270 degree azimuth facing roof—generates more than 100% of the electricity that I use in a large-ish American suburban home.  It is my contention that this shows we can move to 100% renewable energy a lot easier than anyone thinks.  A combination of renewable energy deployment, efficiency, and comment sense conservation can get us there with little sacrifice.  For everyone who says that it cannot be done I welcome you to have a discussion with me about the topic.

Here’s to hoping that August and September can come in big to build a buffer against the gloomy winter months.

Over 600 kWh of Solar Power in June, yet Left Wanting More

June 2018 ended with my home’s solar photovoltaic system have produced approximately 619 kWh for the month:

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This is about on par with May’s production, but several things are off.

See that really low production day on June 26th?  The weather was partly sunny or partly cloudy depending upon your weather vernacular.  That was also about the time that the monitoring data from the app that I use went all haywire.  One day it would show no production, but then update with crazy fluctuating production for that same day later.  I am liable to think that the numbers for the month are off as a result.  Since that period of hiccups everything looks fine, but I am suspicious.

Also, watch your meter readings like a hawk.  I received my electric bill from my local electric coop and it was way off.  How off?  Like someone switched the meter readings for production and consumption.  Instead of showing me positive approximately 500 kWh it was showing almost the same number as a deficit.  Granted, it was easy to figure out because I know how to read my meter but it was discouraging to have to go through the process with customer service.

Without telling me the electric coop replaced my bi-directional meter with a newer model.  It is no skin off my back, but I have lost my tracking of how well my system has done since being installed.  That being said I know that I am net positive more than 600 kWh since the system was installed and I am looking forward to a big month of production in July.