Does Daylight Savings Time Affect Sunlight?

 November 22, 2021

Earlier this month, my home state of Illinois in the US was subjected to another fall time shift, our so called Daylight Savings Time.  The saying is "fall back, spring forward", to help you remember what you need to do to your clocks.  The impact to the human psyche is rather traumatic with this shift of our time devices.  But, be assured that there is no real impact on the overall amount of sun that falls on to the earth, other than what is caused locally by the normal tilt of the earth as it revolves around the sun.  The sun has continued to provide light, heat and power every day, even though our minds may perceive a different amount of sunlight available.

I'm approaching the end of another full year of  maintaining an array of solar panels on my home's roof.  To say maintain is really an overstatement.  I view, daily, the SolarEdge monitor application, and monthly review the results of the solar panel output versus our home's electric consumption.  I really don't do anything to the panel array, inverter, or wiring.

The year 2021 has been a positive solar year.  Solar production has exceeded demand for 8 out of the last 11 months.  This means that for those 8 months, our electric cost has been $ 0.00.  Excess power from the solar system is directed to the grid and generates a credit to our home account.  The credit that has been generated made last month's electric cost also $0.00, even though we consumed more energy from the grid than sent into the grid.  It is possible that next month's bill may also be accommodated via the credit.  Time and sunlight will tell. 

The chart below shows actual kWhour solar production at our home and the consumption of kWhour power. 

As an aside, the months charted above represent billing cycle months, and don't relate exactly to the calendar month.  But close enough.

Solar has been a worthy investment, thus far!

One Full Year Complete

It's given that where we live, Palatine, Illinois, late December and early January have the shortest daylight hours of the year.  Solar is best served in regions with a large number of sunny days.  But our sun availability is still reasonable.

Our solar panel system was installed and tested in the latter part of December 2019.  It was not officially "turned on" to interface with our local power (ComEd) company's grid until noon January 9, 2020.  The first full year of solar production was, therefore, complete on January 8, 2021.  

What does a full year living with solar panels on your roof mean?

Roof Integrity - The installation has proven to be sound and structurally good.  The engineered tie between the PV (photo-voltaic) panel and the roof is basically a lag screw.  There is a critical installation method to ensure zero leakage and full integrity so that the rail system upon which the PV panels are secured meet building code.  As of the end of year 1, there have been no leaks and no installation issues.

Solar Production - for the full year, our system produced 16.12 MWh of energy.  A monthly breakdown of the production is shown in the bar chart below.  Summing all of the bars in the chart equate to 16.12 MWh of energy.  Of note, June, July and August were the highest solar production months.

Distribution of Panel Energy -  Our PV system is comprised of 40 panels.  Each system panel is tracked and it's angular tilt, directional face position on the roof, and proximity to shade elements dictate the level of solar energy production possible.  The physical layout of panels is shown in the following image, with North being at the top of the image.  The skew is how our home is positioned relative to true North. 

Each blue block represents a distinct PV panel (count them, there are 40 blocks).  The panel array accommodates normal roof exhaust stacks and uses various roof pitch sections to provide optimum energy collection.

Note that the two panels that are at the top and to the left (these are the East-most panels) are darker in color.  This indicates that they have the least amount of solar energy production in the past year.  Why?

We have several Aspen trees growing at that corner of the house.  The early morning sun is somewhat shaded by these trees.  Some selective pruning may be required to improve solar production.

The PV panels are installed in a three "string" configuration.  The inverter (the green block) that converts the solar "DC" energy to AC energy (usable by our home) requires such a configuration.

The logical layout is shown to the left.  The purple block shows the full year AC energy,  The green block represents the Inverter.  The uppermost three blocks represent the sum of the individual three strings.  Each string's panel elements are displayed below the primary string block.  String 1.1 has 14 panels.  String 1.2 and String 1.3 each have 13 panels each.

Each string is wired together and every string element (panel) is in close proximity to every other string panel on the roof.  Each string cabling runs separately to the Inverter. 

Benefits to Having Solar - Installing a solar system on your property is not a trivial decision.  There is upfront investment in time and money.  Beyond the environmental benefit of extracting energy from the sun, as opposed to fossil fuels, there is a real, financial benefit.  I won't get into the full details of the benefit, but will provide some summary benefits for the first year of owning solar.

- CO2 Emission Saved - Each kWh of electricity can be generated using fossil fuel, which generates CO2 emissions. The number shown is the quantity of CO2 emissions that would have been generated by an equivalent fossil fuel system.

 =  25,195.94 Lbs.

- Equivalent Trees Planted - Trees absorb CO2, thus reducing CO2 environmental pollution levels. The number shown is the equivalent planting of new trees for reducing CO2 levels.

=  190.38 trees

- Electric Cost Impact - You can determine the annual cost of energy supplied by your power company.  I used my 2019 annual electrical energy cost as the staring base.  I still require energy from my local energy company (ComEd), since solar does not produce when the sun is down, and I do not have battery storage.  The remaining electrical energy need is supplied by solar.  There is no ongoing run cost for the solar system.

= the 2020 (post-solar) cost for all electricity from ComEd was 20.8% of the 2019 (pre-solar) cost

Pray for more sunny days...

Monitoring Improvements

 

Our solar system has been producing now for over 7 months.  Right from the start, I kept a close eye on the data that was generated from the installed system.  Data is originating from two sources:  (1) solar production is monitored and recorded via the Solaredge Inverter and monitoring application, and (2) the household energy consumption detail is monitored from a stand-alone device (Sense) installed within the electrical panel in our home.  Both sets of information can be viewed via computer or mobile phone.

Early on, I knew that I wanted a unified data stream in one monitoring application.  Recently, I  installed an Energy Meter connecting the solar inverter and the household power lines.  Current transformers are used to sense energy Consumption by looping the main power lines to the house.  As a result, the Solaredge Inverter Monitoring application now provides a total picture of all relevant energy flows:

    - Solar Production

    - Energy Imported from the Grid

    - Energy Exported to the Grid

    - Self-Consumed Energy from Solar Production (as it is generated from the solar system)

    - Total Energy Consumed = Energy Imported + Self-Consumed Energy from Solar

A few screen captures of the monitoring system information shown below should help convey the data.

The Original Monitoring

This image shows the solar System Production on August 29, 2020.  The total energy production for the 24 hours of the day was 66.59 kWh.  The monitoring information only included the solar production.

The Updated Monitoring System

This screen capture shows the monitoring of all variables: System Production (a combination of both Self-Consumption and Export) and Consumption (a combination of Self-consumption and Import).  September 11, 2020 was a very cloudy and rainy day with small solar production (only 9.61 kWh of energy.  The Consumption (shown in red) normally averages around 1-2.5 kW, but peaked at 5 PM on this day, due to the electric oven use.  All but a very small amount of the solar energy was self-consumed (shown in blue).  A small amount of exported energy (shown in green), only 0.91 kWh occurred at times when solar production was in excess of consumption.  This energy was exported to the ComEd grid.

This last screen capture shows the monitoring on September 15, 2020 on a relatively sunny day.  Total System Production was 65.34 kWh.  25% of this was Self-consumed, and 75% of this was exported to the grid.  For the day, our home consumed a total of 77.23 kWh of energy, of which only 16.53 kWh was supplied by the solar system.  The normal 1-2.5 kW consumption was significantly higher between midnight and 4 AM because we were charging our Tesla electric car during this time.

 

  

It should be noted that the last screen capture shows the interplay between solar production energy and consumption.  Obviously, solar production only occurs during daylight hours.  But consumption occurs throughout the whole day.

Our home is part of the ComEd Hourly Rate Pricing Program.  This means that energy we import or export is priced at a varying hourly rate.  In the picture above, the price during the Midnight to 4 AM time ranged from 0.8 - 1.3 Cents/ kWh (energy demand is lower for ComEd and they charge less for the hourly energy).  Between the solar production time period, the hourly price was 1.4 - 1.9 cents/ kWh (more demand means that ComEd typically charges more per hour for the energy they supply).

But this means that I am buying energy at a lower price and exporting (selling back to ComEd) at a higher per hour price.  It works out nicely!

Major Milestones

August 2, 2020

Milestones along a path mark accomplishments that are worth observing and celebrating.  The original incentives for 'going solar' were both idealistic and economic.  How can I contribute to the environmental welfare of our planet?  Can solar be both financially viable and environmentally positive?

August 2020 marked the accomplishments of solar production on our system that were noteworthy.

Milestone 1 - A Monthly Production High - As July rolled over into August, the installed solar system reflected the continued month-over-month increase that one may expect.  I speculate that July's peak solar production of 2.012 MWh  (2,012,000 Watt-hour) of energy will be the maximum monthly level  for the calendar year.  The production is directly dependent on the weather conditions, and time is not on my side for a higher peak in this year.  The daily available sun time has been diminishing since Late June - the days are getting shorter. 

The bar-graph above plots by month the 2020 solar production level.  January (01) reflects only 66% of the month in operation.  And August (08) is only partially complete at the time this graph was developed.

Milestone 2 - A System Production Level Total Achievement - There is always something pleasing about reaching certain numerical levels.  Reaching 1.0 MWh (1,000,000 Watt-hour) of lifetime production occurred late in February 2020.  It would take another six months to reach the next order of magnitude level, 10 MWh.  This did occur on August, 4, 2020.  As a point of reference, 10 MWh is about equivalent to the amount of electricity used by about 3,330 homes during one hour.

There were no bells or fireworks after reaching this level, just silent satisfaction.  My monitoring system also provides an estimate of pounds of CO2 emission saved at 15,500 pounds, which is equivalent to roughly 117 trees planted.  Nice.

Milestone 3 - Electric Bill Reductions - The original design of the solar production system predicted an approximate solar production output at 81%  of 'historical' electric usage.  Past electric bills were used as the planning electric consumption base.  Estimating solar production is complicated by weather, panel shading and solar panel efficiencies, plus many other factors.  The electric consumption of our home is also dependent on weather, devices used and lifestyle preferences.  I expected my ComEd (supplier of electricity) electric bill to be lower by a respectable amount, but predicting the level is extremely complicated.

But our milestone achievement has been especially pleasing.  For the last two billing periods (June and July), our actual bill has been $0.  In fact, there has been a credit that has rolled over monthly.  It was a combination of replacing incandescent lights and positive solar output.  This will not continue I am certain, as solar production reduces later in the year, but it is satisfying today.

Other News - And the last bit of news, while not a milestone regarding our system, is the continuing growth of solar in our subdivision.  As of August, we now have 4 homes producing solar energy.  Last November there were 0 homes.  This is still only 3.6% of the total subdivision home count, but it is a positive direction.

Thanks. 

Snow Drops

4/21/2020

April weather in the Chicago-land area is difficult to forecast.  It can be clear with bright blue skies, or dark-clouded and cold with snow flurries.  Or heavy rains with lightening and thunder.  Pick your favorite.

So it has been an interesting solar production month so far.  Every day seems to bring another production record for my installed system.

But the event that I really did not expect was the somewhat startling thump that occurred on two peaceful mornings.  Our morning ritual is to wake up, look out the bedroom window for any unusual stirrings in the neighborhood.  After throwing water on the face, walk down the stairs to the first floor and make coffee.  Sit down with my brew and open up the news.  My dining chair faces the sliding window overlooking our deck, bird feeders and the backyard detention ponds.  It could be pre-dawn or the sun may be up (pretty casual these days).

After recent snowfalls on two days in mid-April, I expected the solar production to be reduced.  That is until the snow melts from the panels.





This is the view on the morning of April 15,2020 after getting approximately 5-6' overnight.




















This is the view on the morning of April 17, 2020 after getting about 4" overnight.

At about 7:45 AM on the 15th and then again on the 17th, we were surprised by the snow drop from overhead.  The picture below shows the remnants of the snow that slid off the roof.

There is no warning of the imminent drop.  But there are 30 feet of glassy panels that are rising along the roof slope up to the peak above the sliding glass door.

If you get enough sun load on the snow, the slippery glass panel surface becomes a great slide.  I have not viewed the avalanche build up on the roof, but it generates enough momentum to shift the snow clean.

And then there is plenty of great panel area to generate energy.





















As I mentioned earlier, April seems to be a good solar month.

Since the beginning of the month, five separate 'largest ever' days of solar production occurred.  Progressively higher 'highs' occurred on April 2, 10, 16, 18 and 20.  And right now, April 21st looks like another high.

Since we are using only about 28-35 KWh of energy a day, I decided to use the excess solar energy today to 'fill up' the electric vehicle during the day.  An EV charge usually is limited to 10 KW and normally requires about 2-4 hours of time (which I would normally do during the night time).

Sunny days are great!

April 2020 Milestone

4/11/2020

As of 5 PM today, we are 21 days into the Illinois "stay at home order".  Our community lifestyle has dramatically changed over thes last 3 weeks.  Because of the order, our buying, traveling and social habits have been minimized to only the essentials.  When I do venture out, the road traffic is minimal.  I have been able to take my neighborhood walks, but social distancing is practiced by almost every one I "meet".  Clearly, life today is different and won't revert to normal for some time.

But, the grass is green and it continues to grow.  The trees have started to bud.  Our Cornelian Cherry Dogwood has blossomed with yellow flowers.  The pollen count is high.  And the sun is rising earlier every day and races to a higher zenith.

The sun part is great for the solar system that was installed in the latter part of December last year.

At this time, my daily ritual is to mentally note where the sun is rising and then check the solar production monitoring application.  Several checks during the day are standard.

April 2020 has brought several different milestones.

Milestone #1 is surpassing 3 MWh of total energy produced, reached in earlier April.

Milestone #2 is achieving the highest level of daily solar energy production, thusfar, at 76.83 KWh produced on April 10, 2020.

 

The chart to the right is taken from the monitoring application display.  It shows centrally the System Production (76.83 KWh), and it also shows the line graph of the Kw energy produced by the solar panel against time.

The granularity of the plot is 15 minute segments.  It shows that the first energy received by the system was in the 6:15 AM segment and was a mere 0.024 KW.  The last bit of energy received was at 7:15 PM and was 0.022 KW.  Peak energy was received at 9:00 AM, 11:30 AM and 1:30 PM, and is limited to 10 KW.

The more abrupt growth of the curve and more gradual downward slope of the curve is a function of the panel and roof position and the path and height of the sun.





Another milestone occurred March 20, 2020 when I received my first ComEd (local power company) billing with a full month of solar production.  It was great to see that the prior billing period reflected a flow of 790 KWh of energy "from the grid", and a flow of 957 KWh of energy TO the grid.  My monitoring system does not yet tell me how much self-generated energy (solar) that I consumed at home, but some simple math can tell me this.

[For Billing Period 2/192020 - 3/19/2020]

Solar Energy produced                               = 1285 KWh
Solar energy pushed to the ComEd Grid =   957 KWh

Solar energy self-consumed                     =   328 KWh
ComEd additional energy required         =   790 KWh
Total Energy required                                = 1118 KWh

So, you may ask, Why do you need to acquire energy from ComEd if your solar system produced more than you required in the billing period?
The answer is that the sun is up only during the day making solar energy.  My consumption is 24 hours a day.  And on some of those billing days, I charged my electric cars in the middle of the night.

Please keep safe and healthy my friends.  Everyone is so dependent on each other to lessen the impact of the Covid-19 pandemic.  As long as the sun continues to shine, we will make it to the other side of this panemic.  I am anxious to see you all then.

A Milestone...

2/21/2020

It's amazing how a sunny day today seems so much more appreciated than it did in the past.  Don't get me wrong, sunny days are always desired, but now it means more.

This week our month-old solar network reached a milestone.  Two milestones in fact.

Date: 2/21/2020
Daily Production:  65.546 KWh  (Milestone #1 = Highest Daily Production)
Lifetime Energy: 1.03 MWh  (Milestone#2 = Surpassing 1 Mega Watt hour Production)

I noted that on that occasion, the solar system had generated the equivalent of 40 trees being planted, or 1588 lbs. of CO2 Emissions Saved.  All for a greener earth!

The differences in energy production is quite noticeable in the above daily bar chart. The three 65 KWh days between the 19-22 dates reflect close-to-the-maximum available power for those days, given the length of the day.  I'm anxious to see my first real ComEd bill which will reflect the Net-Metering aspect of the solar set up.  This is the mechanism to allow both self-consumption of solar energy, as well as pushing solar energy back into the ComEd grid.  I'll have a blog posting to discuss this later.

We've been enjoying more sun.  The days are getting longer and solar energy production is increasing. More power to the sun!