West facing PV array?

Just read an article in Renewable News about facing some of the PV panels west, not trying to face all south to gain some energy harvesting later in the day. The article originated from Austin Texas and a study found that arrays facing west reduced energy use 65% whereas arrays facing south reduced energy use 54%.

Anyone have any thoughts on this and particulary if this may be worth considering for Southern California (san diego area). I have both south and west facing roof areas.

Thanks for any insight.

Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: West facing PV array?
    Just read an article in Renewable News about facing some of the PV panels west

    I would like to read the article, can you post a link?
    There has been considerable discussion on this forum about this... some folks call it "virtual tracking". Try searching for "virtual tracker" or "virtual tracking".


    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    Re: West facing PV array?

    I have about 4k facing south and it was expensive to mount. Due to the cost with mounting, I chose to install 3 strings of 840 watts each on the east side of the barn, 2 strings of 840 watts on the west side, 1 string of 256 watts on the east side, and a single 210 watt panel on the east side for the dedicated 12 volt system. There are still 3 more strings of 840 watts each to install for about 12kw total. When it is cloudy the east / west 'virtual' array will produce more than the same size array facing south at 59 degrees. Even with mounting, the cost was well under $1 per watt for the east / west array. It works for me and I get power early and late with the east array and more overall with the south array. Can't wait to get the Whiz Bang Jr's going to put to use some of the opportunity power available.

    So the answer is it can be very good depending on your situation. Most spend more than $1 per watt on mounting panels, and I got the panels installed for less than $1 per watt, so it was worth it to me.
    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: West facing PV array?

    i'm not so sure east/west is best although it is convenient for some roof mounts. better may be south east and south west for a split system. this covers sunrise and sunset somewhat, but with more collecting capabilities for the mid day collection time period when intensities are highest. even at this the noon period would be 45 degrees off from the pvs with a severe reduction in power production and about a nearly nonexistent winter power production.

    it all depends on individual circumstances and goals for sure. for instance i have my pvs between ssw and sw, but i also have severe shading to the east and se. it is an off grid setup. the southern aiming ideal is not good for me and power production is more than many might think in these 'off' directions.

    might be good to merge this thread being there is that rss thread that was moved into the main body of the forum.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: West facing PV array?

    The "face it South" mindset comes from being able to expose the array to the most sun during every day throughout the year. It is an old idea, and in this age of cheap panels and time-of-use GT plans it may not be valid in every application. What's worse is that usage/power needs may change once you put a system in meaning the 'ideal' alignment for your array may change. Unfortunately for most it is not easy to change that after the install.

    Something more to think about, as if there weren't enough already.