December 23 2013

Today proved to be an interesting day.  Here we are at one of the shortest day light days of the year.  The sun decided to bless us with its presence with intermittent cloud cover. I raised the West Array to maximum to face East.  It extends at a better angle than the 22.5 degree East roof.  During the morning, the West produced at times 50% more power than East and more than South.  That is because the West panels raise up much higher than the slope that the east panels have to conform to.  We developed overcast skies after the noon hour.  For the day, West produced 10% less than South.  East array did not have the chance to catch-up to West as the sun hid behind the clouds for the rest of the day.

Proven For the Day:

Raising West panels resulted in daily harvesting 90% than of South Facing panels in the Month of December. Normally in December West and East panels produce poorly.  East produced 77% of South's average output.

Remember that it's December and the sun sits very, very low on the horizon.  Having West and East panels that track during the day can significantly improve the output of the panels.  This system is designed for optimum output from March to October.

Shaded Panels:

I cut down the branches from two 40 ft pine trees.  The very weak shadow from the tree trunks reduced the output from 6 south facing panels as the shadow tracked across the panels in the morning until noon.  The trees which are about 35 feet from the roof, will be coming down.  This proved having SolarEdge Optimizers really helped to prevent the other panels from decreasing their output.  Three South facing panels get shaded from the West array because of the extremely low angle of the sun.  This will decrease as the sun now tracks back to the east and get higher in the sky.  I did not expect that tiny shading to have any effect but it had a big one.

How did we do compared to others in the Area:

Different areas get different amount of sunlight.  We could only compare to two other locations.  One in Belle River and one in Lasalle.  Normally Lasalle produces the highest amount because they have 20% more installed panels (12 kW DC to our 10 kW DC).  We produced 16 kWH and they produced 12.5 kWH. The other Belle River produced 11.95 kWH.  Flexible Solar monitor more sites and we came in number one today.

You just might say that we smoked them today or got a bit more sunlight.  At this time of year Lasalle will always out produce us because they have a better roof angle.  In the summer, that advantage swings to us, but only for a tiny amount.

Summary:

Benefits of using optimizers really helped today with 9 panels showing the effects of shading.  Moving the West panels to look East significantly increased their production to just below that of South.  If the sun had not gone away, we would most likely produced more than South on the West panels and more on the East also.

The benefits of having individual panel monitoring system also pays big time.  I can see that one panel on the south is not producing as well as others near it.  It does get some shading and but output is lower.  It can be changed with one of our backup panels.

I saw from the Inverter output, that we had a peak power of 7 kW.  This was not recorded by the monitoring system as it didn't last for over 15 min.  It was recorded by our grid TIE power meter.  This was around 10:30 am.  Clouds prevented it from continuing.