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...