In winter when the sun is at an angle less than the pitch of the roof the panels will receive no sunlight.
Solar panels on east and west facing roofs.
And while there is some indication that facing solar panels to the west can also be quite effective for the most part those with east and west facing roofs face a challenge in installing a solar array that will.
However solar panels can be orientated on any roof that faces south of either east or west.
If you look back to systems that were built a few years ago you would typically find them facing south says david wedepohl director of communications and markets at the german solar industry association bsw.
Of course you cannot install east west facing solar panels on your roof if it does not already slant in those directions.
Panels mounted on a standard pitch roof facing east or west will produce approximately 15 less output than panels mounted on a south facing roof of a standard pitch.
Therefore directions like southwest or southeast are fine.
If you went with a professional solar installer they probably had a good reason to install panels facing east rather than west.
However under the right circumstances it is possible to have an east west split of solar panels on a single inverter input like the diagram above imagine the left hand 3 panels facing west and the right hand 3 panels facing east and still have almost the same performance as if they were on separate strings attached to a two seperate inverter inputs.
With east or west facing panels the sun will be behind the roof for half the day.
Technically east facing panels can get as much sun as west facing ones as long as there are no other issues like morning fog or clouds or shade.