Tag Archives: solar

April 2022 Solar PV Production and EV Efficiency 

One word describes April 2022: miserable.  It has been demonstrably colder and windier this year than prior years.  Naturally, it impacted solar PV production and our household’s energy usage:

A total of ~739 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~48 kWh. Had we produced the same amount of electricity as the year before we would have been “in the black” ~116 kWh.  Also, given the difference in weather we probably would have used a lot less electricity.  For the year so far we are “in the red” ~895 kWh.  Year-over-year versus the same period last year we are ~400 kWh more “in the red.”

Production is one part of this, but so is consumption.  As I have described before, we are trying to limit our use of natural gas in the household.  Keeping the thermostat low and using electrical heat in small spaces has worked.  Even with a billing period that was ~10 degrees cooler than the year before we managed to use ~2% fewer therms of natural gas.  For the year we have used 58 fewer therms, which works out to an equivalent of ~1,700 kWh of electricity.  My hope is that May represents a turnaround in fortunes, but the weather has not been kind the past few days.  Cold, windy and rainy is the order of the day.

We feel that this is the right approach to energy usage given all of the problems inherent in the production of natural gas and the high level of renewables utilized in Iowa’s electricity generation mix.  Also, it will allow me to install additional solar panels in a couple of years as our household usage increases.

For the month of January we drove the Nissan Leaf 649.1 miles at an average efficiency of 5.3 miles per kWh.  Year-over-year versus the same period last year we drove ~12.5% more.

This works out to a CO2 avoidance of ~743 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. For the year so far we have avoided ~2,531 pounds of CO2.

March 2022 Solar PV Production and EV Efficiency 

March is the month where we start producing a lot more electricity via our solar panel array.  Check out the month’s numbers below:

A total of ~667 kWh produced for the month.  This was in line with the two years prior—better than 2020 and a little down from 2021.  In terms of electricity production versus consumption my household ended up “in the red” ~119 kWh.  This is trending in the right direction and hopefully April can be the month where we breakthrough into the black producing more electricity than we use.  For the year we are “in the red” ~847 kWh.  In the year prior we were “in the red” ~641 kWh.  The difference can be accounted for in the increased use of electricity for heating small spaces in order to reduce our use of natural gas to heat the entire house.

Based on the information in my natural gas bills we have used ~17% fewer therms of natural gas than the year prior.  This works out to ~57 therms.  Using an equivalent amount of electricity would work out to ~1,670 kWh at a rate of 29.3 kWh per therm.  So, if we use additional electricity at a lower amount we are coming out ahead of the game.  The next big reduction in our natural gas usage is hopefully going to come from the installation of a hybrid air source heat pump water heater.

For the month of January we drove the Nissan Leaf 530.7  miles at an average efficiency of 5.2 miles per kWh.  This works out to a CO2 avoidance of ~606 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. For the year we have avoided ~1,788 pounds of CO2 by driving the Leaf in favor of an ICE.

February 2022 Solar PV Production and EV Efficiency 

February is usually a tough month for solar PV product, but something strange happened in 2022:

Not only was this the best February in history for our solar PV array, but it also bested any prior November, December, or January in terms of production.  Hopefully this is a harbinger of a big year for solar PV production.

A total of ~465 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~245 kWh. In comparison with the prior year we were “better” more than 100 kWh even with a significant increase in EV miles driven.  For the year to date our household is “in the red” ~728 kWh.

Our household effort to use less natural gas, which seems even more important now that energy is becoming a weapon on the world stage, continues apace.  During the last billing period for which I have data we used ~11% fewer therms of natural gas than the year prior.  This works out to ~14 therms.  Using an equivalent amount of electricity would work out to ~410 kWh at a rate of 29.3 kWh per therm.  For the year to date our household has used ~39 fewer therms versus the same period the year prior.  An equivalent amount of electricity would work out to ~1,143 kWh using the same logic as above.

For the month of February we drove the Nissan Leaf 548.6 miles at an average efficiency of 5.0 miles per kWh.  This works out to a CO2 avoidance of ~622 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

For the year to date, we have driven the Nissan Leaf 1,053.3 miles.  This works out to a CO2 avoidance of ~1,183 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

What is really scary is that my daughter received her learner’s permit this month, so she has started putting miles on the Leaf.

January 2022 Solar PV Production and EV Efficiency

January and February are always tough months for solar PV production.  The days are short, the skies are cloudy, and frequently the array is covered in a layer of crusty snow.  You can really tell how covered the array was early in the month:

A total of ~249 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~483 kWh. 

This seems like a lot and it is more than double 2021, but it is actually in line with what my household averaged in 2020.  Furthermore, my wife and I have been making an effort to reduce our natural gas usage and utilize more personal heating.  She uses a radiator style space heater in her home office and I use an electric foot mat heater in my home office.  During the last billing period for which I have data we used ~22% fewer therms of natural gas than the year prior.  This works out to ~25 therms.  Using an equivalent amount of electricity would work out to ~730 kWh at a rate of 29.3 kWh per therm.

We feel that this is the right approach to energy usage given all of the problems inherent in the production of natural gas and the high level of renewables utilized in Iowa’s electricity generation mix.  Also, it will allow me to install additional solar panels in a couple of years as our household usage increases.

For the month of January we drove the Nissan Leaf 504.7 miles at an average efficiency of 4.5 miles per kWh.  It is amazing just how much efficiency you lose driving an EV in the winter with a resistive heater.  It also speaks to just how much waste heat an ICE produces through combustion.  This works out to a CO2 avoidance of ~561 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

December 2021 Solar PV Production and EV Efficiency

December 2021 solar photovoltaic production was up versus the same month last year.  About 43 kWh of additional production is good, especially in a generally garbage month for production.  How did the month look:

A total of ~273 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~256 kWh. 

For the year, my household is ~459 kWh “in the black” or net-positive in terms of electricity production versus consumption.  The prior year we ended “in the black” ~1,040 kWh.  A part of this attributable to not working from home for the first quarter of 2020 and then following that up with a severe downturn in miles drive—a direct proxy for electricity usage in my household due to the Nissan Leaf.  Additionally, we are making an effort to use electricity to heat small spaces this year rather than relying on our natural gas fired furnace.  For the same billing periods in November and December our natural gas usage was down ~41% and ~18% respectively with similar average temperatures.

For the month of December we drove the Nissan Leaf 438.1 miles at an average efficiency of 5.1 miles per kWh.  This works out to a CO2 avoidance of ~498 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

For the year, so far, we have driven ~6,307 miles at an average efficiency of ~5.3 miles per kWh.  This translates into a CO2 avoidance of ~7,210 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

November 2021 Solar PV Production and EV Efficiency

November 2021 solar photovoltaic production was up versus the same month last year.  Granted, it was only 10 kWh difference for the entire month but more is more.  How did the month look:

A total of ~384 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~302 kWh.  Some of the increase in extra electricity usage is attributable to driving our Nissan Leaf more (up almost 40% year-over-year) and a Thanksgiving holiday week with a house full of people.

The other big change year-over-year is that we are trying to use a lot less natural gas to heat our home.  My wife and I work from home full time, so our heating bill has been higher than pre-COVID-19.  However, since we spend the majority of the time in two smallish rooms of the house that have been turned into home offices we have been turning down the thermostat for the whole house and using electric heat.  She runs a little more cold blooded than I do, so in her office she is using a small radiator style space heater to keep her warm.  I am just using an electric foot heater to keep my toes warm, which is about the only part of my body bothered by the cold.  It will be interesting to see if we have made a noticeable difference in our natural gas usage over the course of the winter heating season.

For the year, my household is ~715 kWh “in the black” or net-positive in terms of electricity production versus consumption.

For the month of November we drove the Nissan Leaf 720.2 miles at an average efficiency of 5.2 miles per kWh.  This works out to a CO2 avoidance of ~822 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

For the year, so far, we have driven ~5,869 miles at an average efficiency of ~5.3 miles per kWh.  This translates into a CO2 avoidance of ~6,712 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

October 2021 Solar PV Production and EV Efficiency

October 2021 solar photovoltaic production was down versus the same month last year.  It did turn into a soggy mess of a month toward the end, which was weird given how dry 2021 has been in general.  How did the month look:

A total of ~460kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the red” ~85 kWh. 

For the year, my household is ~1,017 kWh “in the black” or net-positive in terms of electricity production versus consumption.

For the month of October we drove the Nissan Leaf 614.2 miles at an average efficiency of 5.5 miles per kWh.  This works out to a CO2 avoidance of ~707 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

For the year, so far, we have driven ~5,149 miles at an average efficiency of ~5.3 miles per kWh.  This translates into a CO2 avoidance of ~5,890 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

September 2021 Solar PV Production and EV Efficiency

September 2021 was my solar PV array’s best September ever.  Granted, last year it was out of commission for ten days while a new roof was installed on my house because of the derecho.  Damn derecho.  How did the month look:

A total of ~811 kWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the black” ~224 kWh.  The crazy thing?  That is the same amount that we ended up “in the black” last month.  Crazy, right?

For the year, my household is ~1,102 kWh “in the black” or net-positive in terms of electricity production versus consumption.

For the month of September we drove the Nissan Leaf 640.3 miles at an average efficiency of 5.6 miles per kWh.  This works out to a CO2 avoidance of ~739 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region.  Now that we are producing extra electricity, I try to time my recharging when my PV array is producing mad electrons.

For the year, so far, we have driven ~4,535 miles at an average efficiency of ~5.3 miles per kWh.  This translates into a CO2 avoidance of ~5,183 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region. 

The craziest thing, in my opinion, is that around the end of September my wife and I recorded as many days working from home as in all of 2020.  With three months to go that is a lot of working from home in 2021.

August 2021 Solar PV Production and EV Efficiency

August 2021 was kind of a disappointment when compared with the same month a year prior.  If you remember, in August 2020 eastern Iowa was hit by a derecho.  The impact on my solar system is that it was down for approximately one week owing to the lack of grid power.  Even with that lack of generating days, 2021 barely beat 2020:

A total of ~1.01 MWh produced for the month.  In terms of electricity production versus consumption my household ended up “in the black” ~224 kWh.

For the year, my household is ~878 kWh “in the black” or net-positive in terms of electricity production versus consumption. My hope is that we get a good September because the weather seems to be cooperating–lower temps and humidity–and we will not have the solar PV array removed for a roof replacement.

For the month of August we drove the Nissan Leaf 624.2 miles at an average efficiency of 5.6 miles per kWh.  The drop in efficiency compared with prior months just shows what a few trips near highway speeds can do to the numbers.  This works out to a CO2 avoidance of ~721 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region.  Now that we are producing extra electricity, I try to time my recharging when my PV array is producing mad electrons.

For the year, so far, we have driven ~3,894 miles at an average efficiency of ~5.3 miles per kWh.  This translates into a CO2 avoidance of ~4,444 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region.

July 2021 Solar PV Production and EV Efficiency

July 2021 was an interesting month for my solar system’s productivity.  Overall the month was a good one, but it also represents the moment when my system went “net positive” since the installation of a new bi-directional meter a few years ago:

A total of ~1.09 MWh produced for the month, falling shy of the same month a year ago, works out to ~274 kWh “in the black” for the month.  July was a tough month for AC usage due to the high heat and humidity in eastern Iowa.  Although it worked out to be average for the month, the last week or so was a total steam room.

For the year, my household is ~685 kWh “in the black” or net-positive in terms of electricity production versus consumption.

For the month of July we drove the Nissan Leaf 476.3 miles at an average efficiency of 6.2 miles per kWh.  This works out to a CO2 avoidance of ~558 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region.  Now that we are producing extra electricity, I try to time my recharging when my PV array is producing mad electrons.

For the year, so far, we have driven ~3,270 miles at an average efficiency of ~5.2 miles per kWh.  This translates into a CO2 avoidance of ~3,723 pounds versus my truck assuming we pulled every watt for the Nissan Leaf from the grid at an average carbon intensity for my region.