Cheap Panels = No Solar Trackers?

If you can buy a Kyocera panel from our friends at NAWS for $1.81 per watt, isn't it hard to make the argument to buy a $6,000 motorized solar tracker that under a best-case scenario boosts by 40% the output of 12 panels collectively pumping out about 2,500 watts? Unless there are unusual factors like space constraints, wouldn't it make a lot more sense to buy more panels and just use an inexpensive mounting system?

Your thoughts and insight are welcome.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Not all trackers are $6,000: http://www.solar-electric.com/zotrmoforsoe.html

    However, for the most part the "more panels vs. tracker" debate already comes out with more panels ahead most of the time. This will only augment the result.

    But there will always be those sites where tracking is the way to go.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Cheap Panels = No Solar Trackers?

    One of our posters here (Dave Sparks) really does like trackers because of the longer charging time (more hours of usable sun with a tracker). If I understand correctly he feels that the batteries are better served by running a lower peak charging current, but longer charging time (especially during winter).

    A tracker discussion thread from a few years ago

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • stoneunhenged
    stoneunhenged Solar Expert Posts: 39
    Re: Cheap Panels = No Solar Trackers?

    Not just a hypothetical, BTW. I have two solar trackers --including the $6,000 kind-- and I'm debating about just going stationary if I add to the system.
  • SolarLurker
    SolarLurker Solar Expert Posts: 122 ✭✭
    Re: Cheap Panels = No Solar Trackers?

    The economics favor fixed in most cases, if you going to install a ground mount than trackers don't add that much more.

    Trackers have a few hard to quantify advantages, here we get afternoon rain that clears by 5pm during the summer and we get some intense sun from the west. A fixed array would waste all that potential.
  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
    Re: Cheap Panels = No Solar Trackers?

    If you are installing it yourself I'd just go fixed. There are DiY tracking designs you can find on the WWW, but they look like a lot of work.

    Peace, Rolland
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: Cheap Panels = No Solar Trackers?

    And if it's for an off-grid install the economics swing even more in favour of a fixed system because the benefits of a tracker are reduced in winter. So if you're comparing the kWh produced over the whole year then you may see 40% gain - but that figure is much smaller in winter.

    In my location at latitude 42, a 2-axis tracker would produce 31% more energy over the year. But in December, it would produce just 20% more. Adding 20% more panels is going to be much cheaper than a tracker.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    BB. wrote: »
    One of our posters here (Dave Sparks) really does like trackers because of the longer charging time (more hours of usable sun with a tracker). If I understand correctly he feels that the batteries are better served by running a lower peak charging current, but longer charging time (especially during winter).

    A tracker discussion thread from a few years ago

    -Bill

    And nothing has changed really. The cost can keep going down and the strategy of having long hours of power is the same. If you do not need the long hours of power then I agree with you folks. Obviously this is for offgrid only or commercial.

    Most of the year you are off the battery sooner and on the battery later. If you do not have long hours of slow water pumping or if you do not run a heat pump or you don't like deeper discharges, then it is pretty self evident that cheap panels are a better investment. Trackers are also the tool for those who live where they can choose not to run a generator. They can be perfectly aligned with the sun when it pokes out of the clouds. There is one more nicety that I save for later.

    Hey Bill !
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Cheap Panels = No Solar Trackers?

    Hi Dave! :D

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Of course there's the third option which is becoming more financially feasible as prices drop:
    Multiple arrays on separate charge controllers facing in different directions.

    If you wanted to get really clever with this you could have an "East array", "South array", and "West array" - and tailor the sizes according to the predicted power need at the time of the day. For instance the East array would be large enough to get through the Bulk charge stage before midday. The South array would only need to be sufficient for Absorb/Float and loads. The West array would pick up the Float and loads function until the sun was too low to provide any real power.

    Crazy? Perhaps. But it is possible and would work.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    Of course there's the third option which is becoming more financially feasible as prices drop:
    Multiple arrays on separate charge controllers facing in different directions.

    If you wanted to get really clever with this you could have an "East array", "South array", and "West array" - and tailor the sizes according to the predicted power need at the time of the day. For instance the East array would be large enough to get through the Bulk charge stage before midday. The South array would only need to be sufficient for Absorb/Float and loads. The West array would pick up the Float and loads function until the sun was too low to provide any real power.

    Crazy? Perhaps. But it is possible and would work.

    Sort of a pseudo tracker without the mechanical headaches then.
  • Shane Jackson
    Shane Jackson Solar Expert Posts: 49
    Re: Cheap Panels = No Solar Trackers?

    That's exactly what I was thinking. Only limitation is real estate....
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    That's exactly what I was thinking. Only limitation is real estate....
    And some pocket change for the mounts and panels.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    Of course there's the third option which is becoming more financially feasible as prices drop:
    Multiple arrays on separate charge controllers facing in different directions.

    If you wanted to get really clever with this you could have an "East array", "South array", and "West array" - and tailor the sizes according to the predicted power need at the time of the day. For instance the East array would be large enough to get through the Bulk charge stage before midday. The South array would only need to be sufficient for Absorb/Float and loads. The West array would pick up the Float and loads function until the sun was too low to provide any real power.

    Crazy? Perhaps. But it is possible and would work.

    Your close keep guessing!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    Your close keep guessing!

    :p I don't "guess".
    But I do "hint". :p
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Mirrors (snow and gravel)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    Your close keep guessing!

    I am confused why this might not work?
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    solar_dave wrote: »
    I am confused why this might not work?

    It would work.
    But it would be dreadfully inefficient compared to using a tracker.
    Think about it: you'd need 2.5-3 times as many panels to produce the same kW hours per day as a tracked system. Plus two more charge controllers. Panels may be cheap, but they're not that cheap. Not yet anyway.

    In defense of my own crazy idea I have to add that there are some sites that do not lend themselves to trackers but could make use of redundant arrays. Let's just say I happen to know one. ;)
  • Shane Jackson
    Shane Jackson Solar Expert Posts: 49
    Re: Cheap Panels = No Solar Trackers?

    2.5 x 3 times???? I just looked at several graphs and ran some numbers.....

    1KW array facing due south over a 12hr day

    1 = 17%
    2 = 49%
    3 = 74%
    4 = 89%
    5 = 95%
    6 = 100%
    7 = 97 %
    8 = 90 %
    9 = 76%
    10 = 53%
    11 = 22%

    Now if you had identical arrays positioned 30% off (2hrs or 165* + 195*)


    Array 1
    1 = 49%
    2 = 74%
    3 = 89%
    4 = 95%
    5 = 100%
    6 = 97%
    7 = 90 %
    8 = 76 %
    9 = 53%
    10 = 22%
    11 = 0%

    Array #2
    1 = 0%
    2 = 17%
    3 = 49%
    4 = 74%
    5 = 89%
    6 = 95%
    7 = 100 %
    8 = 97 %
    9 = 90%
    10 = 76%
    11 = 53%

    Total:

    1 = 49%
    2 = 91%
    3 = 138%
    4 = 169%
    5 = 189%
    6 = 192%
    7 = 190%
    8 = 173 %
    9 = 143%
    10 = 98%
    11 = 53%

    with 1 array you have 5 hrs of approx 90%+ time. with 2 you have approx 9.

    I know these are just numbers based off a graph and probably would need to be adjusted for the real world. However even with a 25% margin of error on the increase (1hr) you would still have to be at the top of the scale for a tracker to compete (60% output increase). And that is just based on peak time, not total output. Total output would be higher on a 2 array setup.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Here's another way to look at it:

    One 400 Watt array mounted on a tracker vs. three 400 Watt arrays mounted East, South, and West.

    Angles will make a huge difference here. Not only the angle for insolation of the panels but the angle of the sun as it moves through its daily arc.

    The East and West arrays will not get the "4 hours equivalent good sun" we count on for a South-facing array because the early and late hours will not be as intense even if "square on" (which they wouldn't be) due to the sun filtering through more atmosphere. Worst-case scenario you get 2 hours equivalent. This would mean:

    South array = 400 Watts * 4 hours = 1600 Watt hours
    East array = 400 Watts * 2 hours = 800 Watt hours
    West array = 400 Watts * 2 hours = 800 Watt hours
    Total: 3200 Watt hours from 1200 Watts of array.

    400 Watts on tracker * 8 hours = 3200 Watt hours from 400 Watts of array.

    Again, depending on the angles of the East and West arrays there could be significant drop-off in production as the sun shifts from the East to the South to the West arrays. The tracking system will not suffer this potential loss.

    I know: I propose the system and then proceed to shoot it full of holes. But you have to question your own thesis or else it isn't proven. ;)

    Besides, my original idea was to have the largest of the array facing East (probably South-East would be better, depending on the site) for early morning Bulk recharge after night use, with lesser arrays (possible 1/2 or even 1/4 the main array size) on South and South-West facets to maintain the batteries through the day.

    The real point is, don't rule out the possibilities. Solar is highly site-specific and you need to tailor the system not only to the power requirements but also to the availability of sun. Too often that gets left out when system design gets reduced to the simplest rule-of-thumb practices we use here as a starting point.
  • Shane Jackson
    Shane Jackson Solar Expert Posts: 49
    Re: Cheap Panels = No Solar Trackers?

    I would say a 3 angle setup at those extremes is an absolute waste. Anything much more than 30* off due south is max.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    I would say a 3 angle setup at those extremes is an absolute waste. Anything much more than 30* off due south is max.

    Latitude makes a big difference too. If you're way up North like me, it's a waste because the Winter months have so little sun at such a narrow angle of exposure that the two "sideways" arrays will produce practically nothing. By the same token, as you near the equator the panels get closer to laying flat and their angle to the compass points becomes less relevant, so again no real advantage.

    If someone wanted to play PV Watts with this they could examine the cumulative Watt hours for the three arrays vs. a "South-only with tracker" (PV Watts doesn't do trackers but it would be approximately a fixed South array +30% - Dave Sparks would have more info on the accuracy of this for comparative purposes). You could spend a lot of time playing with the possibilities.

    At any rate, this also doesn't address the idea of splitting a large South-facing array into three parts to gain earlier charging and sustained PV output over a longer time. That is worth some examination too.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    i'm with shane on this one as i would say use an example of 2 pvs each of which is 30 degrees off of south but in opposing directions. one east, one west, and one south isn't a good configuration with the exception of being far north in the summer.
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    ...PV Watts doesn't do trackers...
    Sure it does. On the system input page you can select fixed (no tracking), single axis, or dual axis tracking.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    ggunn wrote: »
    Sure it does. On the system input page you can select fixed (no tracking), single axis, or dual axis tracking.

    That's good then.
    It doesn't run at all on my ancient Linux netbook so I'm "flying blind" in my recommendation of using it.
    Guess I'm going to have to get a modern computer one of these days. :blush:
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    You are all getting close but leaving out the key parameter to make it feasable.
    I am making this difficult because it took me some time and I do this for a living.
    I do have 2 systems running this way. Think Offgrid !

    Mike, we tried the smoke part in a wildfire and while there is energy in a smokey day it is not the answer, nice joke though...
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Mike, we tried the smoke part in a wildfire and while there is energy in a smokey day it is not the answer, nice joke though...

    Tell me about it. :cry:
    Picture from 2 years ago. 7:12 AM
    That bright spot is the sun.
    Not much panel power to be had from that!
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    That's good then.
    It doesn't run at all on my ancient Linux netbook so I'm "flying blind" in my recommendation of using it.
    Guess I'm going to have to get a modern computer one of these days. :blush:

    You can run a browser on your computer, can't you? That's all you need for PVWatts; it runs on NREL's computer, not yours.

    http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Crashes.
    My browser often crashes. Even on this site. Some are worse than others.
    Never should have up-dated it.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Cheap Panels = No Solar Trackers?

    Next clue, today, the equinox!

    There were 2 skycranes that probably saved the view. Alot of our neighbors 2 years later still just see scarred ponderosa everywhere.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cheap Panels = No Solar Trackers?
    Crashes.
    My browser often crashes. Even on this site. Some are worse than others.
    Never should have up-dated it.
    Ouch. I sympathize; at home, I am still driving an old Mac G4, which barely runs OS10.4. I'm still on OS9 on my other Mac (also a G4) in my music studio.